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Malley KM, Ruiz AD, Darrow MJ, Danaphongse T, Shiers S, Ahmad FN, Mota-Beltran C, Stanislav BT, Price TJ, Rennaker RL, Kilgard MP, Hays SA. Neural mechanisms responsible for vagus nerve stimulation-dependent enhancement of somatosensory recovery. Sci Rep 2024; 14:19448. [PMID: 39169080 PMCID: PMC11339300 DOI: 10.1038/s41598-024-70091-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 08/13/2024] [Indexed: 08/23/2024] Open
Abstract
Impairments in somatosensory function are a common and often debilitating consequence of neurological injury, with few effective interventions. Building on success in rehabilitation for motor dysfunction, the delivery of vagus nerve stimulation (VNS) combined with tactile rehabilitation has emerged as a potential approach to enhance recovery of somatosensation. In order to maximize the effectiveness of VNS therapy and promote translation to clinical implementation, we sought to optimize the stimulation paradigm and identify neural mechanisms that underlie VNS-dependent recovery. To do so, we characterized the effect of tactile rehabilitation combined with VNS across a range of stimulation intensities on recovery of somatosensory function in a rat model of chronic sensory loss in the forelimb. Consistent with previous studies in other applications, we find that moderate intensity VNS yields the most effective restoration of somatosensation, and both lower and higher VNS intensities fail to enhance recovery compared to rehabilitation without VNS. We next used the optimized, moderate intensity to evaluate the mechanisms that underlie recovery. We find that moderate intensity VNS enhances transcription of Arc, a canonical mediator of synaptic plasticity, in the cortex, and that transcript levels were correlated with the degree of somatosensory recovery. Moreover, we observe that blocking plasticity by depleting acetylcholine in the cortex prevents the VNS-dependent enhancement of somatosensory recovery. Collectively, these findings identify neural mechanisms that subserve VNS-dependent somatosensation recovery and provide a basis for selecting optimal stimulation parameters in order to facilitate translation of this potential intervention.
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Affiliation(s)
- Kaitlyn M Malley
- Texas Biomedical Device Center, Richardson, USA
- School of Behavioral and Brain Sciences, Richardson, USA
| | | | | | | | - Stephanie Shiers
- School of Behavioral and Brain Sciences, Richardson, USA
- Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, TX, USA
| | - Fatima N Ahmad
- Texas Biomedical Device Center, Richardson, USA
- School of Behavioral and Brain Sciences, Richardson, USA
| | - Clareth Mota-Beltran
- Texas Biomedical Device Center, Richardson, USA
- School of Behavioral and Brain Sciences, Richardson, USA
| | - Benjamin T Stanislav
- Texas Biomedical Device Center, Richardson, USA
- School of Behavioral and Brain Sciences, Richardson, USA
| | - Theodore J Price
- School of Behavioral and Brain Sciences, Richardson, USA
- Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, TX, USA
| | - Robert L Rennaker
- Texas Biomedical Device Center, Richardson, USA
- School of Behavioral and Brain Sciences, Richardson, USA
| | - Michael P Kilgard
- Texas Biomedical Device Center, Richardson, USA
- School of Behavioral and Brain Sciences, Richardson, USA
| | - Seth A Hays
- Texas Biomedical Device Center, Richardson, USA.
- School of Behavioral and Brain Sciences, Richardson, USA.
- Department of Bioengineering, Erik Jonsson School of Engineering and Computer Science, University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, USA.
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Carroll AM, Pruitt DT, Riley JR, Danaphongse TT, Rennaker RL, Engineer CT, Hays SA, Kilgard MP. Vagus nerve stimulation during training fails to improve learning in healthy rats. Sci Rep 2024; 14:18955. [PMID: 39147873 PMCID: PMC11327266 DOI: 10.1038/s41598-024-69666-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 08/07/2024] [Indexed: 08/17/2024] Open
Abstract
Learning new skills requires neuroplasticity. Vagus nerve stimulation (VNS) during sensory and motor events can increase neuroplasticity in networks related to these events and might therefore serve to facilitate learning on sensory and motor tasks. We tested if VNS could broadly improve learning on a wide variety of tasks across different skill domains in healthy, female adult rats. VNS was paired with presentation of stimuli or on successful trials during training, strategies known to facilitate plasticity and improve recovery in models of neurological disorders. VNS failed to improve either rate of learning or performance for any of the tested tasks, which included skilled forelimb motor control, speech sound discrimination, and paired-associates learning. These results contrast recent findings from multiple labs which found VNS pairing during training produced learning enhancements across motor, auditory, and cognitive domains. We speculate that these contrasting results may be explained by key differences in task designs, training timelines and animal handling approaches, and that while VNS may be able to facilitate rapid and early learning processes in healthy subjects, it does not broadly enhance learning for difficult tasks.
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Affiliation(s)
- Alan M Carroll
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA.
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA.
| | - David T Pruitt
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Jonathan R Riley
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Tanya T Danaphongse
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Robert L Rennaker
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Bioengineering, Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Crystal T Engineer
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Seth A Hays
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Bioengineering, Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Michael P Kilgard
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
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Schiweck C, Edwin Thanarajah S. Response Letter to "Comment on no consistent evidence for the anti-inflammatory effect of vagus nerve stimulation in humans: A systematic review and meta-analysis". Brain Behav Immun 2024; 119:1019-1020. [PMID: 38479631 DOI: 10.1016/j.bbi.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 03/17/2024] Open
Affiliation(s)
- Carmen Schiweck
- Department of Psychiatry, Psychotherapy and Psychosomatics, Goethe University Frankfurt, Germany
| | - Sharmili Edwin Thanarajah
- Department of Psychiatry, Psychotherapy and Psychosomatics, Goethe University Frankfurt, Germany; Max-Planck Institute for Metabolism Research, Cologne, Germany.
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Carroll AM, Riley JR, Borland MS, Danaphongse TT, Hays SA, Kilgard MP, Engineer CT. Bursts of vagus nerve stimulation paired with auditory rehabilitation fail to improve speech sound perception in rats with hearing loss. iScience 2024; 27:109527. [PMID: 38585658 PMCID: PMC10995867 DOI: 10.1016/j.isci.2024.109527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 09/09/2023] [Accepted: 03/15/2024] [Indexed: 04/09/2024] Open
Abstract
Hearing loss can lead to long-lasting effects on the central nervous system, and current therapies, such as auditory training and rehabilitation, show mixed success in improving perception and speech comprehension. Vagus nerve stimulation (VNS) is an adjunctive therapy that can be paired with rehabilitation to facilitate behavioral recovery after neural injury. However, VNS for auditory recovery has not been tested after severe hearing loss or significant damage to peripheral receptors. This study investigated the utility of pairing VNS with passive or active auditory rehabilitation in a rat model of noise-induced hearing loss. Although auditory rehabilitation helped rats improve their frequency discrimination, learn novel speech discrimination tasks, and achieve speech-in-noise performance similar to normal hearing controls, VNS did not enhance recovery of speech sound perception. These results highlight the limitations of VNS as an adjunctive therapy for hearing loss rehabilitation and suggest that optimal benefits from neuromodulation may require restored peripheral signaling.
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Affiliation(s)
- Alan M. Carroll
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021, USA
| | - Jonathan R. Riley
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021, USA
| | - Michael S. Borland
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, USA
| | - Tanya T. Danaphongse
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, USA
| | - Seth A. Hays
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, USA
- Department of Bioengineering, Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021, USA
| | - Michael P. Kilgard
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021, USA
| | - Crystal T. Engineer
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, USA
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021, USA
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Chen L, Tang C, Wang Z, Zhang L, Gu B, Liu X, Ming D. Enhancing Motor Sequence Learning via Transcutaneous Auricular Vagus Nerve Stimulation (taVNS): An EEG Study. IEEE J Biomed Health Inform 2024; 28:1285-1296. [PMID: 38109248 DOI: 10.1109/jbhi.2023.3344176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Motor learning plays a crucial role in human life, and various neuromodulation methods have been utilized to strengthen or improve it. Transcutaneous auricular vagus nerve stimulation (taVNS) has gained increasing attention due to its non-invasive nature, affordability and ease of implementation. Although the potential of taVNS on regulating motor learning has been suggested, its actual regulatory effect has yet been fully explored. Electroencephalogram (EEG) analysis provides an in-depth understanding of cognitive processes involved in motor learning so as to offer methodological support for regulation of motor learning. To investigate the effect of taVNS on motor learning, this study recruited 22 healthy subjects to participate a single-blind, sham-controlled, and within-subject serial reaction time task (SRTT) experiment. Every subject involved in two sessions at least one week apart and received a 20-minute active/sham taVNS in each session. Behavioral indicators as well as EEG characteristics during the task state, were extracted and analyzed. The results revealed that compared to the sham group, the active group showed higher learning performance. Additionally, the EEG results indicated that after taVNS, the motor-related cortical potential amplitudes and alpha-gamma modulation index decreased significantly and functional connectivity based on partial directed coherence towards frontal lobe was enhanced. These findings suggest that taVNS can improve motor learning, mainly through enhancing cognitive and memory functions rather than simple movement learning. This study confirms the positive regulatory effect of taVNS on motor learning, which is particularly promising as it offers a potential avenue for enhancing motor skills and facilitating rehabilitation.
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Rezapour M, Farrahizadeh M, Akbari M. Effectiveness of transcutaneous vagus nerve stimulation (tVNS) on salicylate-induced tinnitus. Neurosci Lett 2024; 822:137639. [PMID: 38224829 DOI: 10.1016/j.neulet.2024.137639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 01/10/2024] [Accepted: 01/10/2024] [Indexed: 01/17/2024]
Abstract
INTRODUCTION Tinnitus is the most common symptom of auditory system disorders. It affects the quality of life of millions of people, but it is still incurable in most cases. Vagus nerve stimulation (VNS) therapy is a potential new treatment for subjective tinnitus. In this study, transcutaneous vagus nerve stimulation (tVNS) combined with tones was utilized to treat salicylate-induced tinnitus since salicylate is a reliable and convenient approach for rapidly inducing tinnitus. METHODS Wistar rats were divided into acoustic stimulation alone (AS, n = 6), tVNS alone (n = 6), and tVNS with AS (n = 6) groups for behavioral and electrophysiological tests. They were assessed by auditory brainstem response (ABR), prepulse inhibition (PPI), gap prepulse inhibition of the acoustic startle (GPIAS), social interactions, and aggressive behavior tests at baseline and seven days' post-salicylate (175 mg/kg, twice a day) injection. RESULTS The inhibition percentage of the GPIAS test was significantly reduced post-salicylate injection in the tVNS and AS alone groups, while it was not significant in the tVNS with AS group. There was no significant difference in the mean percentage of the GPIAS test between the tVNS groups (with or without AS) after salicylate injections. Social interactions were significantly different in the AS alone group pre- and post-salicylate injections, but they were not significant in other groups. Moreover, the results of aggressive behavior tests showed significantly increased post-salicylate injections in the AS alone group, while they were not significant in the tVNS groups (with or without AS). CONCLUSIONS The current study revealed that the application of tVNS alone produced improved social interaction and mood and alleviated salicylate-induced tinnitus severity. Moreover, combining tVNS with acoustic stimulation can prevent salicylate-induced tinnitus.
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Affiliation(s)
- Mitra Rezapour
- Otorhinolaryngology Research Center, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran; Rehabilitation Research Center, Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Maryam Farrahizadeh
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mehdi Akbari
- Rehabilitation Research Center, Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.
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Malley KM, Ruiz AD, Darrow MJ, Danaphongse T, Shiers S, Ahmad FN, Beltran CM, Stanislav BT, Price T, Ii RLR, Kilgard MP, Hays SA. Neural Mechanisms Responsible for Vagus Nerve Stimulation-Dependent Enhancement of Somatosensory Recovery. RESEARCH SQUARE 2024:rs.3.rs-3873435. [PMID: 38352490 PMCID: PMC10862979 DOI: 10.21203/rs.3.rs-3873435/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Impairments in somatosensory function are a common and often debilitating consequence of neurological injury, with few effective interventions. Building on success in rehabilitation for motor dysfunction, the delivery of vagus nerve stimulation (VNS) combined with tactile rehabilitation has emerged as a potential approach to enhance recovery of somatosensation. In order to maximize the effectiveness of VNS therapy and promote translation to clinical implementation, we sought to optimize the stimulation paradigm and identify neural mechanisms that underlie VNS-dependent recovery. To do so, we characterized the effect of tactile rehabilitation combined with VNS across a range of stimulation intensities on recovery of somatosensory function in a rat model of chronic sensory loss in the forelimb. Consistent with previous studies in other applications, we find that moderate intensity VNS yields the most effective restoration of somatosensation, and both lower and higher VNS intensities fail to enhance recovery compared to rehabilitation without VNS. We next used the optimized intensity to evaluate the mechanisms that underlie recovery. We find that moderate intensity VNS enhances transcription of Arc, a canonical mediator of synaptic plasticity, in the cortex, and that transcript levels were correlated with the degree of somatosensory recovery. Moreover, we observe that blocking plasticity by depleting acetylcholine in the cortex prevents the VNS-dependent enhancement of somatosensory recovery. Collectively, these findings identify neural mechanisms that subserve VNS-dependent somatosensation recovery and provide a basis for selecting optimal stimulation parameters in order to facilitate translation of this potential intervention.
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McHaney JR, Schuerman WL, Leonard MK, Chandrasekaran B. Transcutaneous Auricular Vagus Nerve Stimulation Modulates Performance but Not Pupil Size During Nonnative Speech Category Learning. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2023; 66:3825-3843. [PMID: 37652065 DOI: 10.1044/2023_jslhr-22-00596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
PURPOSE Subthreshold transcutaneous auricular vagus nerve stimulation (taVNS) synchronized with behavioral training can selectively enhance nonnative speech category learning in adults. Prior work has demonstrated that behavioral performance increases when taVNS is paired with easier-to-learn Mandarin tone categories in native English listeners, relative to when taVNS is paired with harder-to-learn Mandarin tone categories or without taVNS. Mechanistically, this temporally precise plasticity has been attributed to noradrenergic modulation. However, prior work did not specifically utilize methodologies that indexed noradrenergic modulation and, therefore, was unable to explicitly test this hypothesis. Our goal for this study was to use pupillometry to gain mechanistic insights into taVNS behavioral effects. METHOD Thirty-eight participants learned to categorize Mandarin tones while pupillometry was recorded. In a double-blinded design, participants were divided into two taVNS groups that, as in the prior study, differed according to whether taVNS was paired with easier-to-learn tones or harder-to-learn tones. Learning performance and pupillary responses were measured using linear mixed-effects models. RESULTS We found that taVNS did not have any tone-specific or group behavioral or pupillary effects. However, in an exploratory analysis, we observed that taVNS did lead to faster rates of learning on trials paired with stimulation, particularly for those who were stimulated at lower amplitudes. CONCLUSIONS Our results suggest that pupillary responses may not be a reliable marker of locus coeruleus-norepinephrine system activity in humans. However, future research should systematically examine the effects of stimulation amplitude on both behavior and pupillary responses. SUPPLEMENTAL MATERIAL https://doi.org/10.23641/asha.24036666.
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Borland MS, Buell EP, Riley JR, Carroll AM, Moreno NA, Sharma P, Grasse KM, Buell JM, Kilgard MP, Engineer CT. Precise sound characteristics drive plasticity in the primary auditory cortex with VNS-sound pairing. Front Neurosci 2023; 17:1248936. [PMID: 37732302 PMCID: PMC10508341 DOI: 10.3389/fnins.2023.1248936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 08/22/2023] [Indexed: 09/22/2023] Open
Abstract
Introduction Repeatedly pairing a tone with vagus nerve stimulation (VNS) alters frequency tuning across the auditory pathway. Pairing VNS with speech sounds selectively enhances the primary auditory cortex response to the paired sounds. It is not yet known how altering the speech sounds paired with VNS alters responses. In this study, we test the hypothesis that the sounds that are presented and paired with VNS will influence the neural plasticity observed following VNS-sound pairing. Methods To explore the relationship between acoustic experience and neural plasticity, responses were recorded from primary auditory cortex (A1) after VNS was repeatedly paired with the speech sounds 'rad' and 'lad' or paired with only the speech sound 'rad' while 'lad' was an unpaired background sound. Results Pairing both sounds with VNS increased the response strength and neural discriminability of the paired sounds in the primary auditory cortex. Surprisingly, pairing only 'rad' with VNS did not alter A1 responses. Discussion These results suggest that the specific acoustic contrasts associated with VNS can powerfully shape neural activity in the auditory pathway. Methods to promote plasticity in the central auditory system represent a new therapeutic avenue to treat auditory processing disorders. Understanding how different sound contrasts and neural activity patterns shape plasticity could have important clinical implications.
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Affiliation(s)
- Michael S. Borland
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Elizabeth P. Buell
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Jonathan R. Riley
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Alan M. Carroll
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Nicole A. Moreno
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Pryanka Sharma
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Katelyn M. Grasse
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
- Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, United States
| | - John M. Buell
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Michael P. Kilgard
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
| | - Crystal T. Engineer
- Department of Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, United States
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, United States
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Hays SA, Rennaker RL, Kilgard MP. How to fail with paired VNS therapy. Brain Stimul 2023; 16:1252-1258. [PMID: 37595833 DOI: 10.1016/j.brs.2023.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/14/2023] [Accepted: 08/15/2023] [Indexed: 08/20/2023] Open
Abstract
Vagus nerve stimulation (VNS) has gained enormous traction as a promising bioelectronic therapy. In particular, the delivery of VNS paired with training to promote neural changes has demonstrated clinical success for stroke recovery and found far-reaching application in other domains, from autism to psychiatric disorders to normal learning. The success of paired VNS has been extensively documented. Here, we consider a more unusual question: why does VNS have such broad utility, and perhaps more importantly, when does VNS not work? We present a discussion of the concepts that underlie VNS therapy and an anthology of studies that describe conditions in which these concepts are violated and VNS fails. We focus specifically on the mechanisms engaged by implanted VNS, and how the parameters of stimulation, stimulation method, pharmacological manipulations, accompanying comorbidities, and specifics of concurrent training interact with these mechanisms to impact the efficacy of VNS therapy. As paired VNS therapy is increasing translated to clinical implementation, a clear understanding of the conditions in which it does, and critically, does not work is fundamental to the success of this approach.
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Affiliation(s)
- Seth A Hays
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, USA; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, USA.
| | - Robert L Rennaker
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, USA; School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Michael P Kilgard
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, USA; School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, USA
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Rufener KS, Wienke C, Salanje A, Haghikia A, Zaehle T. Effects of transcutaneous auricular vagus nerve stimulation paired with tones on electrophysiological markers of auditory perception. Brain Stimul 2023; 16:982-989. [PMID: 37336282 DOI: 10.1016/j.brs.2023.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/12/2023] [Accepted: 06/12/2023] [Indexed: 06/21/2023] Open
Abstract
BACKGROUND Transcutaneous auricular vagus nerve stimulation (taVNS) has been introduced as a non-invasive alternative to invasive vagus nerve stimulation (iVNS). While iVNS paired with tones has been highlighted as a potential effective therapy for the treatment of auditory disorders such as tinnitus, there is still scarce data available confirming the efficacy of non-invasive taVNS. Here, we assessed the effect of taVNS paired with acoustic stimuli on sensory-related electrophysiological responses. METHODS A total of 22 healthy participants were investigated with a taVNS tone-pairing paradigm using a within-subjects design. In a single session pure tones paired with either active taVNS or sham taVNS were repeatedly presented. Novel tones without electrical stimulation served as control condition. Auditory event related potentials and auditory cortex oscillations were compared before and after the tone pairing procedure between stimulation conditions. RESULTS From pre to post pairing, we observed a decrease in the N1 amplitude and in theta power to tones paired with sham taVNS while these electrophysiological measures remained stable for tones paired with active taVNS a pattern mirroring auditory sensory processing of novel, unpaired control tones. CONCLUSION Our results demonstrate the efficacy of a short-term application of non-invasive taVNS to modulate auditory processing in healthy individuals and, thereby, have potential implications for interventions in auditory processing deficits.
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Affiliation(s)
- Katharina S Rufener
- Department of Child and Adolescent Psychiatry and Psychotherapy, Otto-von-Guericke-University Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-University Magdeburg, Germany.
| | - Christian Wienke
- Department of Neurology, Otto-von-Guericke-University Magdeburg, Germany
| | - Alena Salanje
- Department of Neurology, Otto-von-Guericke-University Magdeburg, Germany
| | - Aiden Haghikia
- Department of Neurology, Otto-von-Guericke-University Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-University Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Magdeburg, Germany
| | - Tino Zaehle
- Department of Neurology, Otto-von-Guericke-University Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Otto-von-Guericke-University Magdeburg, Germany
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Ooi QY, Qin X, Yuan Y, Zhang X, Yao Y, Hao H, Li L. Alteration of Excitation/Inhibition Imbalance in the Hippocampus and Amygdala of Drug-Resistant Epilepsy Patients Treated with Acute Vagus Nerve Stimulation. Brain Sci 2023; 13:976. [PMID: 37508908 PMCID: PMC10377456 DOI: 10.3390/brainsci13070976] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/09/2023] [Accepted: 06/16/2023] [Indexed: 07/30/2023] Open
Abstract
An imbalance between excitation (E) and inhibition (I) in the brain has been identified as a key pathophysiology of epilepsy over the years. The hippocampus and amygdala in the limbic system play a crucial role in the initiation and conduction of epileptic seizures and are often referred to as the transfer station and amplifier of seizure activities. Existing animal and imaging studies reveal that the hippocampus and amygdala, which are significant parts of the vagal afferent network, can be modulated in order to generate an antiepileptic effect. Using stereo-electroencephalography (SEEG) data, we examined the E/I imbalance in the hippocampus and amygdala of ten drug-resistant epilepsy children treated with acute vagus nerve stimulation (VNS) by estimating the 1/f power slope of hippocampal and amygdala signals in the range of 1-80 Hz. While the change in the 1/f power slope from VNS-BASE varied between different stimulation amplitudes and brain regions, it was more prominent in the hippocampal region. In the hippocampal region, we found a flatter 1/f power slope during VNS-ON in patients with good responsiveness to VNS under the optimal stimulation amplitude, indicating that the E/I imbalance in the region was improved. There was no obvious change in 1/f power slope for VNS poor responders. For VNS non-responders, the 1/f power slope slightly increased when the stimulation was applied. Overall, this study implies that the regulation of E/I imbalance in the epileptic brain, especially in the hippocampal region, may be an acute intracranial effect of VNS.
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Affiliation(s)
- Qian Yi Ooi
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
| | - Xiaoya Qin
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
- Precision Medicine and Healthcare Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518071, China
| | - Yuan Yuan
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
- Precision Medicine and Healthcare Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518071, China
| | - Xiaobin Zhang
- Department of Functional Neurosurgery, Xiamen Humanity Hospital, Fujian Medical University, Fuzhou 350005, China
| | - Yi Yao
- Department of Functional Neurosurgery, Xiamen Humanity Hospital, Fujian Medical University, Fuzhou 350005, China
- Surgery Division, Epilepsy Center, Shenzhen Children's Hospital, Shenzhen 518038, China
| | - Hongwei Hao
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
| | - Luming Li
- National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
- Precision Medicine and Healthcare Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518071, China
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
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13
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Suminski AJ, Rajala AZ, Birn RM, Mueller EM, Malone ME, Ness JP, Filla C, Brunner K, McMillan AB, Poore SO, Williams JC, Murali D, Brzeczkowski A, Hurley SA, Dingle AM, Zeng W, Lake WB, Ludwig KA, Populin LC. Vagus nerve stimulation in the non-human primate: implantation methodology, characterization of nerve anatomy, target engagement and experimental applications. Bioelectron Med 2023; 9:9. [PMID: 37118841 PMCID: PMC10148417 DOI: 10.1186/s42234-023-00111-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 04/19/2023] [Indexed: 04/30/2023] Open
Abstract
BACKGROUND Vagus nerve stimulation (VNS) is a FDA approved therapy regularly used to treat a variety of neurological disorders that impact the central nervous system (CNS) including epilepsy and stroke. Putatively, the therapeutic efficacy of VNS results from its action on neuromodulatory centers via projections of the vagus nerve to the solitary tract nucleus. Currently, there is not an established large animal model that facilitates detailed mechanistic studies exploring how VNS impacts the function of the CNS, especially during complex behaviors requiring motor action and decision making. METHODS We describe the anatomical organization, surgical methodology to implant VNS electrodes on the left gagus nerve and characterization of target engagement/neural interface properties in a non-human primate (NHP) model of VNS that permits chronic stimulation over long periods of time. Furthermore, we describe the results of pilot experiments in a small number of NHPs to demonstrate how this preparation might be used in an animal model capable of performing complex motor and decision making tasks. RESULTS VNS electrode impedance remained constant over months suggesting a stable interface. VNS elicited robust activation of the vagus nerve which resulted in decreases of respiration rate and/or partial pressure of carbon dioxide in expired air, but not changes in heart rate in both awake and anesthetized NHPs. CONCLUSIONS We anticipate that this preparation will be very useful to study the mechanisms underlying the effects of VNS for the treatment of conditions such as epilepsy and depression, for which VNS is extensively used, as well as for the study of the neurobiological basis underlying higher order functions such as learning and memory.
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Affiliation(s)
- Aaron J Suminski
- Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Translational Neuroengineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Abigail Z Rajala
- Department of Neuroscience, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Rasmus M Birn
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ellie M Mueller
- Department of Neuroscience, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Margaret E Malone
- Department of Neuroscience, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Jared P Ness
- Wisconsin Institute for Translational Neuroengineering, University of Wisconsin-Madison, Madison, WI, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Caitlyn Filla
- Department of Neuroscience, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Kevin Brunner
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Alan B McMillan
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, USA
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Samuel O Poore
- Division of Plastic Surgery, University of Wisconsin-Madison, Madison, WI, USA
| | - Justin C Williams
- Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Translational Neuroengineering, University of Wisconsin-Madison, Madison, WI, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Dhanabalan Murali
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Andrea Brzeczkowski
- Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Translational Neuroengineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Samuel A Hurley
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Aaron M Dingle
- Division of Plastic Surgery, University of Wisconsin-Madison, Madison, WI, USA
| | - Weifeng Zeng
- Division of Plastic Surgery, University of Wisconsin-Madison, Madison, WI, USA
| | - Wendell B Lake
- Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Translational Neuroengineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Kip A Ludwig
- Department of Neurological Surgery, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Translational Neuroengineering, University of Wisconsin-Madison, Madison, WI, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Luis C Populin
- Department of Neuroscience, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA.
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14
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Farrand A, Jacquemet V, Verner R, Owens M, Beaumont E. Vagus nerve stimulation parameters evoke differential neuronal responses in the locus coeruleus. Physiol Rep 2023; 11:e15633. [PMID: 36905173 PMCID: PMC10006695 DOI: 10.14814/phy2.15633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 03/12/2023] Open
Abstract
Vagus nerve stimulation (VNS) is used to treat drug-resistant epilepsy and depression, with additional applications under investigation. The noradrenergic center locus coeruleus (LC) is vital for VNS effects; however, the impact of varying stimulation parameters on LC activation is poorly understood. This study characterized LC activation across VNS parameters. Extracellular activity was recorded in rats' left LC while 11 VNS paradigms, utilizing variable frequencies and bursting characteristics, were pseudorandomly delivered to the left cervical vagus for five cycles. Neurons' change from baseline firing rate and timing response profiles were assessed. The proportion of neurons categorized as responders over 5 VNS cycles doubled in comparison to the first VNS cycle (p < 0.001) for all VNS paradigms, demonstrating an amplification effect. The percentage of positively consistent/positive responders increased for standard VNS paradigms with frequencies ≥10 Hz and for bursting paradigms with shorter interburst intervals and more pulses per burst. The synchrony between pairs of LC neurons increased during bursting VNS but not standard paradigms. Also, the probability of evoking a direct response during bursting VNS was higher with longer interburst intervals and a higher number of pulses per burst. Standard paradigms between 10-30 Hz best positively activates LC with consistency to VNS while the best bursting paradigm to increase activity was 300 Hz, seven pulses per burst separated by 1 s. Bursting VNS was effective in increasing synchrony between pairs of neurons, suggesting a common network recruitment originating from vagal afferents. These results indicate differential activation of LC neurons depending on the VNS parameters delivered.
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Affiliation(s)
- Ariana Farrand
- Department of Biomedical SciencesQuillen College of Medicine, East Tennessee State UniversityJohnson CityTennesseeUSA
| | - Vincent Jacquemet
- Department of Pharmacology and PhysiologyInstitute of Biomedical Engineering, University of MontrealMontrealQuebecCanada
- Research CenterSacred Heart Hospital of MontrealMontrealQuebecCanada
| | - Ryan Verner
- Neuromodulation DivisionLivaNova PLCHoustonTexasUSA
| | - Misty Owens
- Department of Biomedical SciencesQuillen College of Medicine, East Tennessee State UniversityJohnson CityTennesseeUSA
| | - Eric Beaumont
- Department of Biomedical SciencesQuillen College of Medicine, East Tennessee State UniversityJohnson CityTennesseeUSA
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15
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The effect of non-invasive vagus nerve stimulation on memory recall in reading: A pilot study. Behav Brain Res 2023; 438:114164. [PMID: 36265760 DOI: 10.1016/j.bbr.2022.114164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 08/09/2022] [Accepted: 10/15/2022] [Indexed: 11/06/2022]
Abstract
Expert reading acquisition is marked by fluent, effortless decoding, and adequate comprehension skills and is required for modern daily life. In spite of its importance, many individuals struggle with reading comprehension even when decoding skills are adequate. Unfortunately, effective reading comprehension interventions are limited, especially for adults. A growing body of research suggests that non-invasive transcutaneous stimulation of the auricular vagus nerve (taVNS) may drive neural plasticity for low-level reading skills such as speech sound perception and letter-sound learning, but it is unknown whether taVNS can improve higher level skills as well. Thus, the current pilot study was designed to evaluate the effect of taVNS paired with passage reading on reading comprehension performance. Twenty-four typically developing young adults were recruited and screened for baseline reading and working memory skills. Participants received either sham or active taVNS while reading short passages out loud. Immediately following each passage, participants answered a series of test questions that required either direct recall of passage details or more complete comprehension of the passage content. While taVNS did not improve the mechanics of reading (e.g., reading rate or accuracy), there was a significant effect of active taVNS on test performance. This effect was driven by significant improvement on accuracy for memory questions while there was no effect of taVNS on comprehension question accuracy. These findings suggest that taVNS may be beneficial for enhancing memory, but its efficacy may be limited in higher cognitive domains.
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16
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Coa R, La Cava SM, Baldazzi G, Polizzi L, Pinna G, Conti C, Defazio G, Pani D, Puligheddu M. Estimated EEG functional connectivity and aperiodic component induced by vagal nerve stimulation in patients with drug-resistant epilepsy. Front Neurol 2022; 13:1030118. [PMID: 36504670 PMCID: PMC9728998 DOI: 10.3389/fneur.2022.1030118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 10/28/2022] [Indexed: 11/24/2022] Open
Abstract
Background Vagal nerve stimulation (VNS) improves seizure frequency and quality of life in patients with drug-resistant epilepsy (DRE), although the exact mechanism is not fully understood. Previous studies have evaluated the effect of VNS on functional connectivity using the phase lag index (PLI), but none has analyzed its effect on EEG aperiodic parameters (offset and exponent), which are highly conserved and related to physiological functions. Objective This study aimed to evaluate the effect of VNS on PLI and aperiodic parameters and infer whether these changes correlate with clinical responses in subjects with DRE. Materials and methods PLI, exponent, and offset were derived for each epoch (and each frequency band for PLI), on scalp-derived 64-channel EEG traces of 10 subjects with DRE, recorded before and 1 year after VNS. PLI, exponent, and offset were compared before and after VNS for each patient on a global basis, individual scalp regions, and channels and separately in responders and non-responders. A correlation analysis was performed between global changes in PLI and aperiodic parameters and clinical response. Results PLI (global and regional) decreased after VNS for gamma and delta bands and increased for an alpha band in responders, but it was not modified in non-responders. Aperiodic parameters after VNS showed an opposite trend in responders vs. non-responders: both were reduced in responders after VNS, but they were increased in non-responders. Changes in aperiodic parameters correlated with the clinical response. Conclusion This study explored the action of VNS therapy from a new perspective and identified EEG aperiodic parameters as a new and promising method to analyze the efficacy of neuromodulation.
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Affiliation(s)
- Roberta Coa
- Neuroscience Ph.D. Program, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy,*Correspondence: Roberta Coa
| | - Simone Maurizio La Cava
- Department of Electrical and Electronic Engineering, University of Cagliari, Cagliari, Italy
| | - Giulia Baldazzi
- Department of Electrical and Electronic Engineering, University of Cagliari, Cagliari, Italy,Department of Informatics, Bioengineering, Robotics and Systems Engineering, University of Genova, Genova, Italy
| | - Lorenzo Polizzi
- Regional Center for the Diagnosis and Treatment of Adult Epilepsy, Neurology Unit, AOU Cagliari, Cagliari, Italy
| | - Giovanni Pinna
- SC Neurosurgery, Neuroscience and Rehabilitation Department, San Michele Hospital, ARNAS G. Brotzu, Cagliari, Italy
| | - Carlo Conti
- SC Neurosurgery, Neuroscience and Rehabilitation Department, San Michele Hospital, ARNAS G. Brotzu, Cagliari, Italy
| | - Giovanni Defazio
- Regional Center for the Diagnosis and Treatment of Adult Epilepsy, Neurology Unit, AOU Cagliari, Cagliari, Italy,Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Danilo Pani
- Department of Electrical and Electronic Engineering, University of Cagliari, Cagliari, Italy
| | - Monica Puligheddu
- Regional Center for the Diagnosis and Treatment of Adult Epilepsy, Neurology Unit, AOU Cagliari, Cagliari, Italy,Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
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17
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Souza RR, Powers MB, Rennaker RL, McIntyre CK, Hays SA, Kilgard MP. Timing of vagus nerve stimulation during fear extinction determines efficacy in a rat model of PTSD. Sci Rep 2022; 12:16526. [PMID: 36192564 PMCID: PMC9530175 DOI: 10.1038/s41598-022-20301-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 09/12/2022] [Indexed: 11/09/2022] Open
Abstract
Studies have indicated that vagus nerve stimulation (VNS) enhances extinction learning in rodent models. Here, we investigated if pairing VNS with the conditioned stimulus is required for the enhancing effects of VNS. Adult Sprague-Dawley rats were exposed to intense stress followed by fear conditioning training to produce resistant fear. Rats were then implanted with a cuff electrode around the left vagus. After recovery, rats underwent extinction training paired with VNS (0.5 s, 0.8 mA, 100 µs, and 30 Hz) or with Sham VNS (0 mA). VNS rats were randomized into the following subgroups: During VNS (delivered during presentations of the conditioned stimulus, CS), Between VNS (delivered between CS presentations), Continuous VNS (delivered during the entire extinction session), and Dispersed VNS (delivered at longer inter-stimulation intervals across the extinction session). Sham VNS rats failed to extinguish the conditioned fear response over 5 days of repeated exposure to the CS. Rats that received Between or Dispersed VNS showed modest improvement in conditioned fear at the retention test. During and Continuous VNS groups displayed the greatest reduction in conditioned fear. These findings indicate that delivering VNS paired precisely with CS presentations or continuously throughout extinction promotes the maximum enhancement in extinction learning.
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Affiliation(s)
- Rimenez R Souza
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, 75080, USA.
- School of Behavioral Brain Sciences, The University of Texas at Dallas, Bioengineering and Sciences Building, 14.506, 800 West Campbell Road, Richardson, TX, 75080, USA.
| | - Mark B Powers
- Baylor University Medical Center, Dallas, TX, 75246, USA
| | - Robert L Rennaker
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, 75080, USA
- School of Behavioral Brain Sciences, The University of Texas at Dallas, Bioengineering and Sciences Building, 14.506, 800 West Campbell Road, Richardson, TX, 75080, USA
- Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Christa K McIntyre
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, 75080, USA
- School of Behavioral Brain Sciences, The University of Texas at Dallas, Bioengineering and Sciences Building, 14.506, 800 West Campbell Road, Richardson, TX, 75080, USA
| | - Seth A Hays
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, 75080, USA
- Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Michael P Kilgard
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, 75080, USA
- School of Behavioral Brain Sciences, The University of Texas at Dallas, Bioengineering and Sciences Building, 14.506, 800 West Campbell Road, Richardson, TX, 75080, USA
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18
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Bowles S, Hickman J, Peng X, Williamson WR, Huang R, Washington K, Donegan D, Welle CG. Vagus nerve stimulation drives selective circuit modulation through cholinergic reinforcement. Neuron 2022; 110:2867-2885.e7. [PMID: 35858623 DOI: 10.1016/j.neuron.2022.06.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 04/22/2022] [Accepted: 06/17/2022] [Indexed: 12/23/2022]
Abstract
Vagus nerve stimulation (VNS) is a neuromodulation therapy for a broad and expanding set of neurologic conditions. However, the mechanism through which VNS influences central nervous system circuitry is not well described, limiting therapeutic optimization. VNS leads to widespread brain activation, but the effects on behavior are remarkably specific, indicating plasticity unique to behaviorally engaged neural circuits. To understand how VNS can lead to specific circuit modulation, we leveraged genetic tools including optogenetics and in vivo calcium imaging in mice learning a skilled reach task. We find that VNS enhances skilled motor learning in healthy animals via a cholinergic reinforcement mechanism, producing a rapid consolidation of an expert reach trajectory. In primary motor cortex (M1), VNS drives precise temporal modulation of neurons that respond to behavioral outcome. This suggests that VNS may accelerate motor refinement in M1 via cholinergic signaling, opening new avenues for optimizing VNS to target specific disease-relevant circuitry.
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Affiliation(s)
- Spencer Bowles
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jordan Hickman
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Xiaoyu Peng
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - W Ryan Williamson
- IDEA Core, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Rongchen Huang
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kayden Washington
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Dane Donegan
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Cristin G Welle
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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19
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Adcock KS, Danaphongse T, Jacob S, Rallapalli H, Torres M, Haider Z, Seyedahmadi A, Morrison RA, Rennaker RL, Kilgard MP, Hays SA. Vagus nerve stimulation does not improve recovery of forelimb motor or somatosensory function in a model of neuropathic pain. Sci Rep 2022; 12:9696. [PMID: 35690673 PMCID: PMC9188565 DOI: 10.1038/s41598-022-13621-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/10/2022] [Indexed: 11/20/2022] Open
Abstract
Nerve injury affecting the upper limb is a leading cause of lifelong disability. Damage to the nerves in the arm often causes weakness and somatosensory dysfunction ranging from numbness to pain. Previous studies show that combining brief bursts of electrical vagus nerve stimulation (VNS) with motor or tactile rehabilitation can restore forelimb function after median and ulnar nerve injury, which causes hyposensitivity of the ventral forelimb. Here, we sought to determine whether this approach would be similarly effective in a model of radial nerve injury that produces allodynia in the ventral forelimb. To test this, rats underwent complete transection of the radial nerve proximal to the elbow followed by tubular repair. In the first experiment, beginning ten weeks after injury, rats received six weeks of tactile rehabilitation, consisting of mechanical stimulation of either the dorsal or ventral region of the forepaw in the injured limb, with or without concurrent VNS. In a second experiment, a separate cohort of rats underwent six weeks of forelimb motor rehabilitative training with or without paired VNS. Contrary to findings in previous models of hyposensitivity, VNS therapy fails to improve recovery of either somatosensory or motor function in the forelimb after radial nerve injury. These findings describe initial evidence that pain may limit the efficacy of VNS therapy and thus highlight a characteristic that should be considered in future studies that seek to develop this intervention.
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Affiliation(s)
- Katherine S Adcock
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA.,School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Tanya Danaphongse
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Sarah Jacob
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Harshini Rallapalli
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Miranda Torres
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Zainab Haider
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Armin Seyedahmadi
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Robert A Morrison
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA.,School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Robert L Rennaker
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA.,School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Michael P Kilgard
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA.,School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA
| | - Seth A Hays
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX, 75080-3021, USA. .,School of Behavioral and Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA. .,Department of Bioengineering, Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, 75080-3021, USA.
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20
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Brougher J, Aziz U, Adari N, Chaturvedi M, Jules A, Shah I, Syed S, Thorn CA. Self-Administration of Right Vagus Nerve Stimulation Activates Midbrain Dopaminergic Nuclei. Front Neurosci 2022; 15:782786. [PMID: 34975384 PMCID: PMC8716493 DOI: 10.3389/fnins.2021.782786] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022] Open
Abstract
Background: Left cervical vagus nerve stimulation (l-VNS) is an FDA-approved treatment for neurological disorders including epilepsy, major depressive disorder, and stroke, and l-VNS is increasingly under investigation for a range of other neurological indications. Traditional l-VNS is thought to induce therapeutic neuroplasticity in part through the coordinated activation of multiple broadly projecting neuromodulatory systems in the brain. Recently, it has been reported that striking lateralization exists in the anatomical and functional connectivity between the vagus nerves and the dopaminergic midbrain. These emerging findings suggest that VNS-driven activation of this important plasticity-promoting neuromodulatory system may be preferentially driven by targeting the right, rather than the left, cervical nerve. Objective: To compare the effects of right cervical VNS (r-VNS) vs. traditional l-VNS on self-administration behavior and midbrain dopaminergic activation in rats. Methods: Rats were implanted with a stimulating cuff electrode targeting either the right or left cervical vagus nerve. After surgical recovery, rats underwent a VNS self-administration assay in which lever pressing was paired with r-VNS or l-VNS delivery. Self-administration was followed by extinction, cue-only reinstatement, and stimulation reinstatement sessions. Rats were sacrificed 90 min after completion of behavioral training, and brains were removed for immunohistochemical analysis of c-Fos expression in the dopaminergic ventral tegmental area (VTA) and substantia nigra pars compacta (SNc), as well as in the noradrenergic locus coeruleus (LC). Results: Rats in the r-VNS cohort performed significantly more lever presses throughout self-administration and reinstatement sessions than did rats in the l-VNS cohort. Moreover, this appetitive behavioral responding was associated with significantly greater c-Fos expression among neuronal populations within the VTA, SNc, and LC. Differential c-Fos expression following r-VNS vs. l-VNS was particularly prominent within dopaminergic midbrain neurons. Conclusion: Our results support the existence of strong lateralization within vagal-mesencephalic signaling pathways, and suggest that VNS targeted to the right, rather than left, cervical nerve preferentially activates the midbrain dopaminergic system. These findings raise the possibility that r-VNS could provide a promising strategy for enhancing dopamine-dependent neuroplasticity, opening broad avenues for future research into the efficacy and safety of r-VNS in the treatment of neurological disease.
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Affiliation(s)
- Jackson Brougher
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Umaymah Aziz
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Nikitha Adari
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Muskaan Chaturvedi
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Aryela Jules
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Iqra Shah
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Saba Syed
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
| | - Catherine A Thorn
- Department of Neuroscience, University of Texas at Dallas, Richardson, TX, United States
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21
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Shaping plasticity with non-invasive brain stimulation in the treatment of psychiatric disorders: Present and future. HANDBOOK OF CLINICAL NEUROLOGY 2022; 184:497-507. [PMID: 35034757 PMCID: PMC9985830 DOI: 10.1016/b978-0-12-819410-2.00028-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The final chapter of this book addresses plasticity in the setting of treating psychiatric disorders. This chapter largely focuses on the treatment of depression and reviews the established antidepressant brain stimulation treatments, focusing on plasticity and maladaptive plasticity. Depression is a unique neuropsychiatric disease in that the brain goes from a healthy state into a pathologic state, and then, with appropriate treatment, can return to health often without permanent sequelae. Depression thus differs fundamentally from neurodegenerative brain diseases like Parkinson's disease or stroke. Some have theorized that depression involves a lack of flexibility or a lack of plasticity. The proven brain stimulation methods for treating depression cause plastic changes and include acute and maintenance electroconvulsive therapy (ECT), acute and maintenance transcranial magnetic stimulation (TMS), and chronically implanted cervical vagus nerve stimulation (VNS). These treatments vary widely in their speed of onset and durability. This variability in onset speed and durability raises interesting, and so far, largely unanswered questions about the underlying neurobiological mechanisms and forms of plasticity being invoked. The chapter also covers exciting recent work with vagus nerve stimulation (VNS) that is delivered paired with behaviors to cause learning and memory and plasticity changes. Taken together these current and future brain stimulation treatments for psychiatric disorders are especially promising. They are unlocking how to shape the brain in diseases to restore balance and health, with an increasing understanding of how to effectively and precisely induce therapeutic neuroplastic changes in the brain.
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22
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Vagus Nerve Stimulation as a Treatment for Fear and Anxiety in Individuals with Autism Spectrum Disorder. JOURNAL OF PSYCHIATRY AND BRAIN SCIENCE 2022; 7. [PMID: 36303861 PMCID: PMC9600938 DOI: 10.20900/jpbs.20220007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Anxiety disorders affect a large percentage of individuals who have an autism spectrum disorder (ASD). In children with ASD, excessive anxiety is also linked to gastrointestinal problems, self-injurious behaviors, and depressive symptoms. Exposure-based cognitive behavioral therapies are effective treatments for anxiety disorders in children with ASD, but high relapse rates indicate the need for additional treatment strategies. This perspective discusses evidence from preclinical research, which indicates that vagus nerve stimulation (VNS) paired with exposure to fear-provoking stimuli and situations could offer benefits as an adjuvant treatment for anxiety disorders that coexist with ASD. Vagus nerve stimulation is approved for use in the treatment of epilepsy, depression, and more recently as an adjuvant in rehabilitative training following stroke. In preclinical models, VNS shows promise in simultaneously enhancing consolidation of extinction memories and reducing anxiety. In this review, we will present potential mechanisms by which VNS could treat fear and anxiety in ASD. We also discuss potential uses of VNS to treat depression and epilepsy in the context of ASD, and noninvasive methods to stimulate the vagus nerve.
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23
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Ludwig M, Wienke C, Betts MJ, Zaehle T, Hämmerer D. Current challenges in reliably targeting the noradrenergic locus coeruleus using transcutaneous auricular vagus nerve stimulation (taVNS). Auton Neurosci 2021; 236:102900. [PMID: 34781120 DOI: 10.1016/j.autneu.2021.102900] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/03/2021] [Accepted: 10/15/2021] [Indexed: 12/11/2022]
Abstract
Transcutaneous auricular vagus nerve stimulation (taVNS), as a non-invasive brain stimulation technique may influence the locus coeruleus-norepinephrine system (LC-NE system) via modulation of the Vagus Nerve (VN) which projects to the LC. Few human studies exist examining the effects of taVNS on the LC-NE system and studies to date assessing the ability of taVNS to target the LC yield heterogeneous results. The aim of this review is to present an overview of the current challenges in assessing effects of taVNS on LC function and how translational approaches spanning animal and human research can help in this regard. A particular emphasis of the review discusses how the effects of taVNS may be influenced by changes in structure and function of the LC-NE system across the human lifespan and in disease.
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Affiliation(s)
- Mareike Ludwig
- Institute for Cognitive Neurology and Dementia Research, Faculty of Medicine, University Hospital Magdeburg, Germany; CBBS Center for Behavioral Brain Sciences, Magdeburg, Germany.
| | - Christian Wienke
- Department of Neurology, Section of Neuropsychology, Otto-v.-Guericke University, Magdeburg, Germany; CBBS Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Matthew J Betts
- Institute for Cognitive Neurology and Dementia Research, Faculty of Medicine, University Hospital Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE), Otto-von-Guericke University Magdeburg, Magdeburg, Germany; CBBS Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Tino Zaehle
- Department of Neurology, Section of Neuropsychology, Otto-v.-Guericke University, Magdeburg, Germany; CBBS Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Dorothea Hämmerer
- Institute for Cognitive Neurology and Dementia Research, Faculty of Medicine, University Hospital Magdeburg, Germany; Institute of Cognitive Neuroscience, University College London, London, UK; Department of Psychology, University of Innsbruck; CBBS Center for Behavioral Brain Sciences, Magdeburg, Germany
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24
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Tseng CT, Gaulding SJ, Dancel CLE, Thorn CA. Local activation of α2 adrenergic receptors is required for vagus nerve stimulation induced motor cortical plasticity. Sci Rep 2021; 11:21645. [PMID: 34737352 PMCID: PMC8568982 DOI: 10.1038/s41598-021-00976-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 10/20/2021] [Indexed: 11/09/2022] Open
Abstract
Vagus nerve stimulation (VNS) paired with rehabilitation training is emerging as a potential treatment for improving recovery of motor function following stroke. In rats, VNS paired with skilled forelimb training results in significant reorganization of the somatotopic cortical motor map; however, the mechanisms underlying this form of VNS-dependent plasticity remain unclear. Recent studies have shown that VNS-driven cortical plasticity is dependent on noradrenergic innervation of the neocortex. In the central nervous system, noradrenergic α2 receptors (α2-ARs) are widely expressed in the motor cortex and have been critically implicated in synaptic communication and plasticity. In current study, we examined whether activation of cortical α2-ARs is necessary for VNS-driven motor cortical reorganization to occur. Consistent with previous studies, we found that VNS paired with motor training enlarges the map representation of task-relevant musculature in the motor cortex. Infusion of α2-AR antagonists into M1 blocked VNS-driven motor map reorganization from occurring. Our results suggest that local α2-AR activation is required for VNS-induced cortical reorganization to occur, providing insight into the mechanisms that may underlie the neuroplastic effects of VNS therapy.
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Affiliation(s)
- Ching-Tzu Tseng
- School of Behavioral and Brain Sciences, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75080, USA
| | - Solomon J Gaulding
- School of Behavioral and Brain Sciences, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75080, USA
| | - Canice Lei E Dancel
- School of Behavioral and Brain Sciences, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75080, USA
| | - Catherine A Thorn
- School of Behavioral and Brain Sciences, University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX, 75080, USA.
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25
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Keute M, Gharabaghi A. Brain plasticity and vagus nerve stimulation. Auton Neurosci 2021; 236:102876. [PMID: 34537681 DOI: 10.1016/j.autneu.2021.102876] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/01/2021] [Accepted: 08/29/2021] [Indexed: 01/01/2023]
Abstract
After damage to the central nervous system, caused by traumatic injury or ischemia, plasticity becomes critically important for functional recovery. When this inherent capacity to adapt is limited despite training, external stimulation may support this process. Vagus nerve stimulation (VNS) is an effective method to enhance the effect of motor rehabilitation training on functional recovery. However, the mechanisms by which VNS exerts beneficial effects on cortical plasticity are not completely understood. Experimental work suggests that VNS fosters a neurochemical milieu that facilitates synaptic plasticity and supports reinforcement mechanisms. Animal studies, furthermore, suggest that VNS delivery is time-critical and that optima in the parameter space need to be titrated for effect maximization. Human studies suggest that VNS modifies corticospinal excitability. First studies in stroke patients show positive results for invasive, and also promising findings for non-invasive VNS.
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Affiliation(s)
- Marius Keute
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, University of Tuebingen, Tuebingen, Germany.
| | - Alireza Gharabaghi
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, University of Tuebingen, Tuebingen, Germany
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26
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Bucksot JE, Chandler CR, Intharuck NM, Rennaker RL, Kilgard MP, Hays SA. Validation of a parameterized, open-source model of nerve stimulation. J Neural Eng 2021; 18. [PMID: 34330105 DOI: 10.1088/1741-2552/ac1983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/30/2021] [Indexed: 11/12/2022]
Abstract
Peripheral nerve stimulation is an effective treatment for various neurological disorders. The method of activation and stimulation parameters used impact the efficacy of the therapy, which emphasizes the need for tools to model this behavior. Computational modeling of nerve stimulation has proven to be a useful tool for estimating stimulation thresholds, optimizing electrode design, and exploring previously untested stimulation methods. Despite their utility, these tools require access to and familiarity with several pieces of specialized software. A simpler, streamlined process would increase accessibility significantly. We developed an open-source, parameterized model with a simple online user interface that allows user to adjust up to 36 different parameters (https://nervestimlab.utdallas.edu). The model accurately predicts fiber activation thresholds for nerve and electrode combinations reported in literature. Additionally, it replicates characteristic differences between stimulation methods, such as lower thresholds with monopolar stimulation as compared to tripolar stimulation. The model predicted that the difference in threshold between monophasic and biphasic waveforms, a well-characterized phenomenon, is not present during stimulation with bipolar electrodes.In vivotesting on the rat sciatic nerve validated this prediction, which has not been previously reported. The accuracy of the model when compared to previous experiments, as well as the ease of use and accessibility to generate testable hypotheses, indicate that this software may represent a useful tool for a variety of nerve stimulation applications.
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Affiliation(s)
- Jesse E Bucksot
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 W Campbell Road, Richardson, TX, United States of America
| | - Collin R Chandler
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 W Campbell Road, Richardson, TX, United States of America.,Texas Biomedical Device Center, 800 W Campbell Road, Richardson, TX, United States of America
| | - Navaporn M Intharuck
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 W Campbell Road, Richardson, TX, United States of America
| | - Robert L Rennaker
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 W Campbell Road, Richardson, TX, United States of America.,The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 W Campbell Road, Richardson, TX, United States of America.,Texas Biomedical Device Center, 800 W Campbell Road, Richardson, TX, United States of America
| | - Michael P Kilgard
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 W Campbell Road, Richardson, TX, United States of America.,Texas Biomedical Device Center, 800 W Campbell Road, Richardson, TX, United States of America
| | - Seth A Hays
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 W Campbell Road, Richardson, TX, United States of America.,The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 W Campbell Road, Richardson, TX, United States of America.,Texas Biomedical Device Center, 800 W Campbell Road, Richardson, TX, United States of America
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27
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Salemi-Mokri-Boukani P, Karimian-Sani-Varjovi H, Safari MS. The promoting effect of vagus nerve stimulation on Lempel-Ziv complexity index of consciousness. Physiol Behav 2021; 240:113553. [PMID: 34375622 DOI: 10.1016/j.physbeh.2021.113553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 07/27/2021] [Accepted: 08/05/2021] [Indexed: 10/20/2022]
Abstract
Recent studies suggest that vagus nerve stimulation (VNS) promotes cognitive and behavioral restoration after traumatic brain injuries. As vagus nerve has wide effects over the brain and visceral organs, stimulation of the sensory/visceral afferents might have a therapeutic potential to modulate the level of consciousness. One of the most important challenges in studying consciousness is objective evaluation of the consciousness level. Brain complexity that can be measured through Lempel-Ziv complexity (LZC) index was used as a novel mathematical approach for objective measurement of consciousness. The main goal of our study was to examine the effects of VNS on LZC index of consciousness. In this study, we did VNS on the anesthetized rats, and simultaneously LFPs recording was performed in two different cortical areas of primary somatosensory (S1) or visual (V1) cortex. LZC and the amplitude of slow waves were computed during different periods of VNS. We found that the LZC index during VNS period was significantly higher in both of the cortical areas of S1 and V1. Slow-wave activity decreased during VNS in S1, while there was no significant change in V1. Our findings showed that VNS can augment the consciousness level, and LZC index is a more sensitive parameter for detecting the level of consciousness.
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Affiliation(s)
- Paria Salemi-Mokri-Boukani
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Habib Karimian-Sani-Varjovi
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Brain Future Institute, Tehran, Iran
| | - Mir-Shahram Safari
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Brain Future Institute, Tehran, Iran.
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28
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Thompson SL, O'Leary GH, Austelle CW, Gruber E, Kahn AT, Manett AJ, Short B, Badran BW. A Review of Parameter Settings for Invasive and Non-invasive Vagus Nerve Stimulation (VNS) Applied in Neurological and Psychiatric Disorders. Front Neurosci 2021; 15:709436. [PMID: 34326720 PMCID: PMC8313807 DOI: 10.3389/fnins.2021.709436] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 06/22/2021] [Indexed: 12/12/2022] Open
Abstract
Vagus nerve stimulation (VNS) is an established form of neuromodulation with a long history of promising applications. Earliest reports of VNS in the literature date to the late 1800’s in experiments conducted by Dr. James Corning. Over the past century, both invasive and non-invasive VNS have demonstrated promise in treating a variety of disorders, including epilepsy, depression, and post-stroke motor rehabilitation. As VNS continues to rapidly grow in popularity and application, the field generally lacks a consensus on optimum stimulation parameters. Stimulation parameters have a significant impact on the efficacy of neuromodulation, and here we will describe the longitudinal evolution of VNS parameters in the following categorical progression: (1) animal models, (2) epilepsy, (3) treatment resistant depression, (4) neuroplasticity and rehabilitation, and (5) transcutaneous auricular VNS (taVNS). We additionally offer a historical perspective of the various applications and summarize the range and most commonly used parameters in over 130 implanted and non-invasive VNS studies over five applications.
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Affiliation(s)
- Sean L Thompson
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Georgia H O'Leary
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Christopher W Austelle
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Elise Gruber
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Alex T Kahn
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Andrew J Manett
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Baron Short
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Bashar W Badran
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
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29
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Vagus Nerve Stimulation with Mild Stimulation Intensity Exerts Anti-Inflammatory and Neuroprotective Effects in Parkinson's Disease Model Rats. Biomedicines 2021; 9:biomedicines9070789. [PMID: 34356853 PMCID: PMC8301489 DOI: 10.3390/biomedicines9070789] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/02/2021] [Accepted: 07/05/2021] [Indexed: 12/17/2022] Open
Abstract
Background: The major surgical treatment for Parkinson’s disease (PD) is deep brain stimulation (DBS), but a less invasive treatment is desired. Vagus nerve stimulation (VNS) is a relatively safe treatment without cerebral invasiveness. In this study, we developed a wireless controllable electrical stimulator to examine the efficacy of VNS on PD model rats. Methods: Adult female Sprague-Dawley rats underwent placement of a cuff-type electrode and stimulator on the vagus nerve. Following which, 6-hydroxydopamine (6-OHDA) was administered into the left striatum to prepare a PD model. VNS was started immediately after 6-OHDA administration and continued for 14 days. We evaluated the therapeutic effects of VNS with behavioral and immunohistochemical outcome assays under different stimulation intensity (0.1, 0.25, 0.5 and 1 mA). Results: VNS with 0.25–0.5 mA intensity remarkably improved behavioral impairment, preserved dopamine neurons, reduced inflammatory glial cells, and increased noradrenergic neurons. On the other hand, VNS with 0.1 mA and 1 mA intensity did not display significant therapeutic efficacy. Conclusions: VNS with 0.25–0.5 mA intensity has anti-inflammatory and neuroprotective effects on PD model rats induced by 6-OHDA administration. In addition, we were able to confirm the practicality and effectiveness of the new experimental device.
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30
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Souza RR, Robertson NM, McIntyre CK, Rennaker RL, Hays SA, Kilgard MP. Vagus nerve stimulation enhances fear extinction as an inverted-U function of stimulation intensity. Exp Neurol 2021; 341:113718. [PMID: 33844986 DOI: 10.1016/j.expneurol.2021.113718] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/22/2021] [Accepted: 04/05/2021] [Indexed: 02/07/2023]
Abstract
Studies in rodents indicate that pairing vagus nerve stimulation (VNS) with extinction training enhances fear extinction. However, the role of stimulation parameters on the effects of VNS remains largely unknown. Identifying the optimal stimulation intensity is a critical step in clinical translation of neuromodulation-based therapies. Here, we sought to investigate the role of stimulation intensity in rats receiving VNS paired with extinction training in a rat model for Posttraumatic Stress Disorder (PTSD). Male Sprague-Dawley rats underwent single prolonged stress followed by a severe fear conditioning training and were implanted with a VNS device. After recovery, independent groups of rats were exposed to extinction training paired with sham (0 mA) or VNS at different intensities (0.4, 0.8, or 1.6 mA). VNS intensities of 0.4 mA or 0.8 mA decreased conditioned fear during extinction training compared to sham stimulation. Pairing extinction training with moderate VNS intensity of 0.8 mA produced significant reduction in conditioned fear during extinction retention when rats were tested a week after VNS-paired extinction. High intensity VNS at 1.6 mA failed to enhance extinction. These findings indicate that a narrow range of VNS intensities enhances extinction learning, and suggest that the 0.8 mA VNS intensity used in earlier rodent and human stroke studies may also be the optimal in using VNS as an adjuvant in exposure therapies for PTSD.
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Affiliation(s)
- Rimenez R Souza
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States.
| | - Nicole M Robertson
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Christa K McIntyre
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Robert L Rennaker
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Seth A Hays
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Michael P Kilgard
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
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31
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Short-Term Effects of Vagus Nerve Stimulation on Learning and Evoked Activity in Auditory Cortex. eNeuro 2021; 8:ENEURO.0522-20.2021. [PMID: 34088737 PMCID: PMC8240839 DOI: 10.1523/eneuro.0522-20.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/13/2021] [Accepted: 04/16/2021] [Indexed: 11/21/2022] Open
Abstract
Chronic vagus nerve stimulation (VNS) has been shown to facilitate learning, but effects of acute VNS on neural coding and behavior remain less well understood. Ferrets implanted with cuff electrodes on the vagus nerve were trained by classical conditioning on an auditory tone frequency-reward association. One tone was associated with reward while another tone was not. Tone frequencies and reward associations were changed every 2 d, requiring learning of a new relationship. When tones were paired with VNS, animals consistently learned the new association within 2 d. When VNS occurred randomly between trials, learning within 2 d was unreliable. In passively listening animals, neural activity in primary auditory cortex (A1) and pupil size were recorded before and after acute VNS-tone pairing. After pairing with a neuron’s best-frequency (BF) tone, responses by a subpopulation of neurons were reduced. VNS paired with an off-BF tone or during intertrial intervals had no effect. The BF-specific reduction in neural responses after VNS remained, even after regressing out changes explained by pupil-indexed arousal. VNS induced brief dilation in the pupil, and the size of this change predicted the magnitude of persistent changes in the neural response. This interaction suggests that fluctuations in neuromodulation associated with arousal gate the long-term VNS effects on neural activity.
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32
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Urbin MA, Lafe CW, Simpson TW, Wittenberg GF, Chandrasekaran B, Weber DJ. Electrical stimulation of the external ear acutely activates noradrenergic mechanisms in humans. Brain Stimul 2021; 14:990-1001. [PMID: 34154980 DOI: 10.1016/j.brs.2021.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Transcutaneous stimulation of the external ear is thought to recruit afferents of the auricular vagus nerve, providing a means to activate noradrenergic pathways in the central nervous system. Findings from human studies examining the effects of auricular stimulation on noradrenergic biomarkers have been mixed, possibly relating to the limited and variable parameter space explored to date. OBJECTIVE We tested the extent to which brief pulse trains applied to locations of auricular innervation (canal and concha) elicit acute pupillary responses (PRs) compared to a sham location (lobe). Pulse amplitude and frequency were varied systematically to examine effects on PR features. METHODS Participants (n = 19) underwent testing in three separate experiments, each with stimulation applied to a different external ear location. Perceptual threshold (PT) was measured at the beginning of each experiment. Pulse trains (∼600 ms) consisting of different amplitude (0.0xPT, 0.8xPT, 1.0xPT, 1.5xPT, 2.0xPT) and frequency (25 Hz, 300 Hz) combinations were administered during eye tracking procedures. RESULTS Stimulation to all locations elicited PRs which began approximately halfway through the pulse train and peaked shortly after the final pulse (≤1 s). PR size and incidence increased with pulse amplitude and tended to be greatest with canal stimulation. Higher pulse frequency shortened the latency of PR onset and peak dilation. Changes in pupil diameter elicited by pulse trains were weakly associated with baseline pupil diameter. CONCLUSION (s): Auricular stimulation elicits acute PRs, providing a basis to synchronize neuromodulator release with task-related neural spiking which preclinical studies show is a critical determinant of therapeutic effects. Further work is needed to dissociate contributions from vagal and non-vagal afferents mediating activation of the biomarker.
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Affiliation(s)
- Michael A Urbin
- Human Engineering Research Laboratories, VA RR&D Center of Excellence, VA Pittsburgh Healthcare System, Pittsburgh, PA, USA; Rehabilitation Neural Engineering Laboratories, University of Pittsburgh, Pittsburgh, PA, USA; Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Charles W Lafe
- Human Engineering Research Laboratories, VA RR&D Center of Excellence, VA Pittsburgh Healthcare System, Pittsburgh, PA, USA; Rehabilitation Neural Engineering Laboratories, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tyler W Simpson
- Rehabilitation Neural Engineering Laboratories, University of Pittsburgh, Pittsburgh, PA, USA; Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, USA
| | - George F Wittenberg
- Human Engineering Research Laboratories, VA RR&D Center of Excellence, VA Pittsburgh Healthcare System, Pittsburgh, PA, USA; Rehabilitation Neural Engineering Laboratories, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bharath Chandrasekaran
- Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA, USA
| | - Douglas J Weber
- Rehabilitation Neural Engineering Laboratories, University of Pittsburgh, Pittsburgh, PA, USA; Department of Mechanical Engineering and the Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA
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Collins L, Boddington L, Steffan PJ, McCormick D. Vagus nerve stimulation induces widespread cortical and behavioral activation. Curr Biol 2021; 31:2088-2098.e3. [DOI: 10.1016/j.cub.2021.02.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 02/01/2021] [Accepted: 02/17/2021] [Indexed: 01/02/2023]
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Morrison RA, Danaphongse TT, Abe ST, Stevens ME, Ezhil V, Seyedahmadi A, Adcock KS, Rennaker RL, Kilgard MP, Hays SA. High intensity VNS disrupts VNS-mediated plasticity in motor cortex. Brain Res 2021; 1756:147332. [PMID: 33539792 PMCID: PMC7971691 DOI: 10.1016/j.brainres.2021.147332] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/13/2021] [Accepted: 01/22/2021] [Indexed: 12/20/2022]
Abstract
Vagus nerve stimulation (VNS) paired with motor rehabilitation enhances recovery of function after neurological injury in rats and humans. This effect is ascribed to VNS-dependent facilitation of plasticity in motor networks. Previous studies document an inverted-U relationship between VNS intensity and cortical plasticity, such that moderate intensities increase plasticity, while low or high intensity VNS does not. We tested the interaction of moderate and high intensity VNS trains to probe the mechanisms that may underlie VNS-dependent plasticity. Rats performed a behavioral task where VNS was paired with jaw movement during chewing. For five days, subjects received 100 pairings of moderate intensity VNS (Standard VNS), 100 pairings alternating between moderate and high intensity VNS (Interleaved VNS), or 50 pairings of moderate intensity VNS (Short VNS) approximately every 8 s. After the final behavioral session, intracortical microstimulation (ICMS) was used to evaluate movement representations in motor cortex. 100 pairings of moderate intensity VNS enhanced motor cortex plasticity. Replacing half of moderate intensity stimulation with high intensity VNS blocked this enhancement of plasticity. Removing high intensity stimulation, leaving only 50 pairings of moderate intensity VNS, reinstated plasticity. These results demonstrate that there is a period for at least 8 s after high intensity stimulation in which moderate intensity VNS is not able to engage mechanisms required for synaptic reorganization. More importantly, this study demonstrates that changes in stimulation parameters are a critical determinant of the magnitude of plasticity and likely the efficacy of VNS-enhanced recovery.
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Affiliation(s)
- Robert A Morrison
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States.
| | - Tanya T Danaphongse
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Stephanie T Abe
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Madison E Stevens
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Vikram Ezhil
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Armin Seyedahmadi
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Katherine S Adcock
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Robert L Rennaker
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Michael P Kilgard
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Seth A Hays
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Richardson, TX, United States
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Souza RR, Oleksiak CR, Tabet MN, Rennaker RL, Hays SA, Kilgard MP, McIntyre CK. Vagus nerve stimulation promotes extinction generalization across sensory modalities. Neurobiol Learn Mem 2021; 181:107425. [PMID: 33771710 DOI: 10.1016/j.nlm.2021.107425] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/12/2021] [Accepted: 03/19/2021] [Indexed: 11/29/2022]
Abstract
Traumatic experiences involve complex sensory information, and individuals with trauma-related psychological disorders, such as posttraumatic stress disorder (PTSD), can exhibit abnormal fear to numerous different stimuli that remind them of the trauma. Vagus nerve stimulation (VNS) enhances extinction of auditory fear conditioning in rat models for PTSD. We recently found that VNS-paired extinction can also promote extinction generalization across different auditory cues. Here we tested whether VNS can enhance extinction of olfactory fear and promote extinction generalization across auditory and olfactory sensory modalities. Male Sprague Dawley rats were implanted with a stimulating cuff on the cervical vagus nerve. Rats then received two days of fear conditioning where olfactory (amyl acetate odor) and auditory (9 kHz tones) stimuli were concomitantly paired with footshock. Twenty-four hours later, rats were given three days of sham or VNS-paired extinction (5 stimulations, 30-sec trains at 0.4 mA) overlapping with presentation of either the olfactory or the auditory stimulus. Two days later, rats were given an extinction retention test where avoidance of the olfactory stimulus or freezing to the auditory stimulus were measured. VNS-paired with exposure to the olfactory stimulus during extinction reduced avoidance of the odor in the retention test. VNS-paired with exposure to the auditory stimulus during extinction also decreased avoidance of the olfactory cue, and VNS paired with exposure to the olfactory stimulus during extinction reduced freezing when the auditory stimulus was presented in the retention test. These results indicate that VNS enhances extinction of olfactory fear and promotes extinction generalization across different sensory modalities. Extinction generalization induced by VNS may therefore improve outcomes of exposure-based therapies.
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Affiliation(s)
- Rimenez R Souza
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Cecily R Oleksiak
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Michel N Tabet
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Robert L Rennaker
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Seth A Hays
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Michael P Kilgard
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Christa K McIntyre
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
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Butler AG, O'Callaghan EL, Allen AM, McDougall SJ. Use of a physiological reflex to standardize vagal nerve stimulation intensity improves data reproducibility in a memory extinction assay. Brain Stimul 2021; 14:450-459. [PMID: 33647477 DOI: 10.1016/j.brs.2021.02.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Modulating brainstem activity, via electrical vagus nerve stimulation (VNS), influences cognitive functions, including memory. However, controlling for changes in stimulus efficacy during chronic studies, and response variability between subjects, is problematic. OBJECTIVE/HYPOTHESIS We hypothesized that recruitment of an autonomic reflex, the Hering-Breuer reflex, would provide robust confirmation of VNS efficacy. We compared this to measurement of electrode resistance over time. We also examined whether VNS modulates contextual memory extinction. METHODS Electrodes for VNS and diaphragm electromyography recording were implanted into anesthetized Sprague Dawley rats. When conscious, we measured the electrode resistance as well as the minimum VNS current required to evoke the Hering-Breuer reflex, before, and after, an inhibitory avoidance assay - a two chamber, dark/light model, where the dark compartment was paired with an aversive foot shock. The extinction of this contextual memory was assessed in sham and VNS treated rats, with VNS administered for 30 s at 1.5 times the Hering-Breuer reflex threshold during extinction memory formation. RESULTS Assessment of VNS-evoked Hering-Breuer reflex successfully identified defective electrodes. VNS accelerated extinction memory and decreased multiple physiological metrics of fear expression. We observed an inverse relationship between memory extinction and respiratory rate during the behavioural assay. Additionally, no current - response relationship between VNS and extinction memory formation was established. CONCLUSION These data demonstrate that reliable, experimental VNS studies can be produced by verifying reflex initiation as a consequence of stimulation. Further, studies could be standardised by indexing stimulator efficacy to initiation of autonomic reflexes.
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Affiliation(s)
- Andrew G Butler
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia; Department of Physiology, University of Melbourne, Parkville, Victoria, Australia
| | - Erin L O'Callaghan
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia
| | - Allen M Allen
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
| | - Stuart J McDougall
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.
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Keute M, Machetanz K, Berelidze L, Guggenberger R, Gharabaghi A. Neuro-cardiac coupling predicts transcutaneous auricular vagus nerve stimulation effects. Brain Stimul 2021; 14:209-216. [PMID: 33422683 DOI: 10.1016/j.brs.2021.01.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/24/2020] [Accepted: 01/04/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Transcutaneous auricular Vagus Nerve Stimulation (taVNS) is a non-invasive neuromodulation technique that may constitute an effective treatment for a wide range of neurological, psychiatric, and medical conditions. One key challenge in taVNS research is the high interindividual response variability. To gain an understanding of this variability, reliable biomarkers for taVNS responsiveness would be highly desirable. In this study, we investigated physiological candidate biomarkers while systematically varying stimulation conditions and observing physiological state characteristics. METHODS Forty-four healthy young adults received taVNS and sham-stimulation. Subjects were pseudo-randomly assigned to stimulation of the left or right ear. Each subject underwent six blocks of stimulation. Across blocks, respiration-locking (inhalation-locked taVNS vs. exhalation-locked taVNS vs. sham) and the electrode location (tragus vs. cymba conchae) were varied. We analyzed heart rate (HR), various heart rate variability (HRV) scores, and neuro-cardiac coupling (NCC), indexed by the relationship between electroencephalographic delta power and heartbeat length. RESULTS We observed an effect of taVNS on HR and HRV scores during, but not after stimulation. The direction of the effects was consistent with parasympathetic activation. We did not observe any systematic influence of the stimulation conditions that we varied. However, we found baseline NCC scores to be significant predictors for the individual effect of taVNS on HRV scores. CONCLUSION Cardiac effects of taVNS indicate parasympathetic activation. These effects were short lived, which might explain that some previous studies were unable to detect them. We propose NCC as a novel candidate biomarker for responsiveness to taVNS.
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Affiliation(s)
- Marius Keute
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, And Tuebingen NeuroCampus, University of Tuebingen, Tuebingen, Germany.
| | - Kathrin Machetanz
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, And Tuebingen NeuroCampus, University of Tuebingen, Tuebingen, Germany
| | - Levan Berelidze
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, And Tuebingen NeuroCampus, University of Tuebingen, Tuebingen, Germany
| | - Robert Guggenberger
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, And Tuebingen NeuroCampus, University of Tuebingen, Tuebingen, Germany
| | - Alireza Gharabaghi
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, And Tuebingen NeuroCampus, University of Tuebingen, Tuebingen, Germany.
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Darrow MJ, Mian TM, Torres M, Haider Z, Danaphongse T, Seyedahmadi A, Rennaker RL, Hays SA, Kilgard MP. The tactile experience paired with vagus nerve stimulation determines the degree of sensory recovery after chronic nerve damage. Behav Brain Res 2021; 396:112910. [PMID: 32971197 PMCID: PMC7572822 DOI: 10.1016/j.bbr.2020.112910] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/21/2020] [Accepted: 09/14/2020] [Indexed: 12/22/2022]
Abstract
Loss of sensory function is a common consequence of neurological injury. Recent clinical and preclinical evidence indicates vagus nerve stimulation (VNS) paired with tactile rehabilitation, consisting of delivery of a variety of mechanical stimuli to the hyposensitive skin surface, yields substantial and long-lasting recovery of somatosensory function after median and ulnar nerve transection and repair. Here, we tested the hypothesis that a specific component of the tactile rehabilitation paired with VNS is necessary for recovery of somatosensory function. In a second experiment in a separate cohort, we investigated whether VNS paired with tactile rehabilitation could improve skilled forelimb motor function. Elements of the study design, including planned sample size, assessments, and statistical comparisons, were preregistered prior to beginning data collection (https://osf.io/3tm8u/). Animals received a peripheral nerve injury (PNI) causing chronic sensory loss. Eight weeks after injury, animals were given a VNS implant followed by six weeks of tactile rehabilitation sessions consisting of repeated application of one of two distinct mechanical stimuli, a filament or a paintbrush, to the previously denervated forepaw. VNS paired with either filament indentation or brushing of the paw significantly improved recovery of forelimb withdrawal thresholds after PNI compared to tactile rehabilitation without VNS. The effect size was twice as large when VNS was paired with brushing compared to VNS paired with point indentation. An independent replication in a second cohort confirmed that VNS paired with brush restored forelimb withdrawal thresholds to normal. These rats displayed significant improvements in performance on a skilled forelimb task compared to rats that did not receive VNS. These findings support the utility of pairing VNS with tactile rehabilitation to improve recovery of somatosensory and motor function after neurological injury. Additionally, this study demonstrates that the sensory characteristics of the rehabilitation paired with VNS determine the degree of recovery.
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Affiliation(s)
- Michael J Darrow
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Department of Bioengineering, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Tabarak M Mian
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Miranda Torres
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Zainab Haider
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Tanya Danaphongse
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Armin Seyedahmadi
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Robert L Rennaker
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Department of Bioengineering, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Seth A Hays
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Department of Bioengineering, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, United States.
| | - Michael P Kilgard
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Department of Bioengineering, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, United States
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Thakkar VJ, Engelhart AS, Khodaparast N, Abadzi H, Centanni TM. Transcutaneous auricular vagus nerve stimulation enhances learning of novel letter-sound relationships in adults. Brain Stimul 2020; 13:1813-1820. [PMID: 33127581 DOI: 10.1016/j.brs.2020.10.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 09/22/2020] [Accepted: 10/21/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Reading is a critical skill in modern society but is significantly more difficult to acquire during adulthood. Many adults are required to learn a new orthography after this window closes for personal or vocational reasons and while many programs and training methods exist for learning to read in adulthood, none result in native-like fluency. Implantable cervical vagus nerve stimulation is capable of driving neural plasticity but is invasive and not practical as a reading intervention. OBJECTIVE The goal of the current study was to evaluate whether non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) is effective at enhancing novel orthography acquisition in young adults. METHODS We enrolled 37 typically developing participants and randomly assigned them to a computer control, device sham control, earlobe stimulation control, or experimental transcutaneous auricular stimulation (taVNS) group. Participants then learned novel letter-sound correspondences in Hebrew over five training lessons. Performance was assessed using three measures to evaluate various aspects of reading: Letter ID, Automaticity, and Decoding. RESULTS The taVNS group significantly outperformed the three control groups on both the Automaticity and Decoding tasks. There was no difference on the Letter ID task. CONCLUSIONS These results demonstrate, for the first time, that taVNS is capable of improving aspects of reading acquisition in adults. These findings have potential implications for a wide range of cognitive tasks.
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Affiliation(s)
- Vishal J Thakkar
- Department of Psychology, Texas Christian University, Fort Worth, TX, 76129, USA.
| | - Abby S Engelhart
- Department of Psychology, Texas Christian University, Fort Worth, TX, 76129, USA.
| | | | - Helen Abadzi
- Department of Psychology, University of Texas Arlington, Arlington, TX, 76019, USA.
| | - Tracy M Centanni
- Department of Psychology, Texas Christian University, Fort Worth, TX, 76129, USA.
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De Ridder D, Langguth B, Vanneste S. Vagus nerve stimulation for tinnitus: A review and perspective. PROGRESS IN BRAIN RESEARCH 2020; 262:451-467. [PMID: 33931191 DOI: 10.1016/bs.pbr.2020.08.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Vagus nerve stimulation is a promising new tool in the treatment of chronic tinnitus. Current protocols involve pairing sounds, which exclude the tinnitus frequency, with simultaneous vagus nerve stimulation (VNS). This is based on extensive preclinical animal studies that demonstrate that pairing non-tinnitus sounds with VNS results in a tonotopic map plasticity. It is thought that by expanding the non-tinnitus sound representation, it is possible to overturn the expanded tonotopic map associated with the tinnitus frequency in these animal models. These findings have been translated into a clinical approach, where a clinically significant, but moderate improvement, in tinnitus distress and a modest benefit in tinnitus loudness perception has been shown. Yet, pairing tinnitus matched sound to VNS may produce tinnitus improvement by Pavlovian conditioning, in which the distressful tinnitus sound becomes associated with a relaxing "rest and digest" response from activation of the vagus nerve. If this hypothesis is correct, beneficial effects should be achieved with paired sounds that resemble the tinnitus sounds as much as possible. In conclusion, although the potential to use VNS to drive neural plasticity to reduce or eliminate the neural drivers of ongoing tinnitus is exciting, much work is needed to more completely understand the neural basis of tinnitus and to develop tailored therapies to address the suffering caused by this heterogeneous condition. Whether pairing of the vagus stimulation with non-tinnitus or tinnitus-matched sounds is essential is still to be determined.
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Affiliation(s)
- Dirk De Ridder
- Department of Surgical Sciences, Section of Neurosurgery, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.
| | - Berthold Langguth
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany
| | - Sven Vanneste
- Lab for Clinical and Integrative Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, United States; Global Brain Health Institute & Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
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Adcock KS, Chandler C, Buell EP, Solorzano BR, Loerwald KW, Borland MS, Engineer CT. Vagus nerve stimulation paired with tones restores auditory processing in a rat model of Rett syndrome. Brain Stimul 2020; 13:1494-1503. [PMID: 32800964 DOI: 10.1016/j.brs.2020.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 07/26/2020] [Accepted: 08/07/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Rett syndrome is a rare neurological disorder associated with a mutation in the X-linked gene MECP2. This disorder mainly affects females, who typically have seemingly normal early development followed by a regression of acquired skills. The rodent Mecp2 model exhibits many of the classic neural abnormalities and behavioral deficits observed in individuals with Rett syndrome. Similar to individuals with Rett syndrome, both auditory discrimination ability and auditory cortical responses are impaired in heterozygous Mecp2 rats. The development of therapies that can enhance plasticity in auditory networks and improve auditory processing has the potential to impact the lives of individuals with Rett syndrome. Evidence suggests that precisely timed vagus nerve stimulation (VNS) paired with sound presentation can drive robust neuroplasticity in auditory networks and enhance the benefits of auditory therapy. OBJECTIVE The aim of this study was to investigate the ability of VNS paired with tones to restore auditory processing in Mecp2 transgenic rats. METHODS Seventeen female heterozygous Mecp2 rats and 8 female wild-type (WT) littermates were used in this study. The rats were exposed to multiple tone frequencies paired with VNS 300 times per day for 20 days. Auditory cortex responses were then examined following VNS-tone pairing therapy or no therapy. RESULTS Our results indicate that Mecp2 mutation alters auditory cortex responses to sounds compared to WT controls. VNS-tone pairing in Mecp2 rats improves the cortical response strength to both tones and speech sounds compared to untreated Mecp2 rats. Additionally, VNS-tone pairing increased the information contained in the neural response that can be used to discriminate between different consonant sounds. CONCLUSION These results demonstrate that VNS-sound pairing may represent a strategy to enhance auditory function in individuals with Rett syndrome.
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Affiliation(s)
- Katherine S Adcock
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA
| | - Collin Chandler
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA
| | - Elizabeth P Buell
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA
| | - Bleyda R Solorzano
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA
| | - Kristofer W Loerwald
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA
| | - Michael S Borland
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA
| | - Crystal T Engineer
- The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA; The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road BSB11, Richardson, TX, 75080, USA.
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Llanos F, McHaney JR, Schuerman WL, Yi HG, Leonard MK, Chandrasekaran B. Non-invasive peripheral nerve stimulation selectively enhances speech category learning in adults. NPJ SCIENCE OF LEARNING 2020; 5:12. [PMID: 32802406 PMCID: PMC7410845 DOI: 10.1038/s41539-020-0070-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 06/05/2020] [Indexed: 05/30/2023]
Abstract
Adults struggle to learn non-native speech contrasts even after years of exposure. While laboratory-based training approaches yield learning, the optimal training conditions for maximizing speech learning in adulthood are currently unknown. Vagus nerve stimulation has been shown to prime adult sensory-perceptual systems towards plasticity in animal models. Precise temporal pairing with auditory stimuli can enhance auditory cortical representations with a high degree of specificity. Here, we examined whether sub-perceptual threshold transcutaneous vagus nerve stimulation (tVNS), paired with non-native speech sounds, enhances speech category learning in adults. Twenty-four native English-speakers were trained to identify non-native Mandarin tone categories. Across two groups, tVNS was paired with the tone categories that were easier- or harder-to-learn. A control group received no stimulation but followed an identical thresholding procedure as the intervention groups. We found that tVNS robustly enhanced speech category learning and retention of correct stimulus-response associations, but only when stimulation was paired with the easier-to-learn categories. This effect emerged rapidly, generalized to new exemplars, and was qualitatively different from the normal individual variability observed in hundreds of learners who have performed in the same task without stimulation. Electroencephalography recorded before and after training indicated no evidence of tVNS-induced changes in the sensory representation of auditory stimuli. These results suggest that paired-tVNS induces a temporally precise neuromodulatory signal that selectively enhances the perception and memory consolidation of perceptually salient categories.
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Affiliation(s)
- Fernando Llanos
- Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA 15260 USA
| | - Jacie R. McHaney
- Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA 15260 USA
| | - William L. Schuerman
- Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143 USA
| | - Han G. Yi
- Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143 USA
| | - Matthew K. Leonard
- Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143 USA
| | - Bharath Chandrasekaran
- Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA 15260 USA
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43
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Clinically-derived vagus nerve stimulation enhances cerebrospinal fluid penetrance. Brain Stimul 2020; 13:1024-1030. [DOI: 10.1016/j.brs.2020.03.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 02/07/2020] [Accepted: 03/18/2020] [Indexed: 02/07/2023] Open
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Vaucher E, Laliberté G, Higgins MC, Maheux M, Jolicoeur P, Chamoun M. Cholinergic potentiation of visual perception and vision restoration in rodents and humans. Restor Neurol Neurosci 2020; 37:553-569. [PMID: 31839615 DOI: 10.3233/rnn-190947] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND The cholinergic system is a potent neuromodulator system that plays a critical role in cortical plasticity, attention, and learning. Recently, it was found that boosting this system during perceptual learning robustly enhances sensory perception in rodents. In particular, pairing cholinergic activation with visual stimulation increases neuronal responses, cue detection ability, and long-term facilitation in the primary visual cortex. The mechanisms of cholinergic enhancement are closely linked to attentional processes, long-term potentiation, and modulation of the excitatory/inhibitory balance. Some studies currently examine this effect in humans. OBJECTIVE The present article reviews the research from our laboratory, examining whether potentiating the central cholinergic system could help visual perception and restoration. METHODS Electrophysiological or pharmacological enhancement of the cholinergic system are administered during a visual training. Electrophysiological responses and perceptual learning performance are investigated before and after the training in rats and humans. This approach's ability to restore visual capacities following a visual deficit induced by a partial optic nerve crush is also investigated in rats. RESULTS The coupling of visual training to cholinergic stimulation improved visual discrimination and visual acuity in rats, and improved residual vision after a deficit. These changes were due to muscarinic and nicotinic transmissions and were associated with a functional improvement of evoked potentials. In humans, potentiation of cholinergic transmission with 5 mg of donepezil showed improved learning and ocular dominance plasticity, although this treatment was ineffective in augmenting the perceptual threshold and electroencephalography. CONCLUSIONS Potential therapeutic outcomes ought to facilitate vision restoration using commercially available cholinergic agents combined with visual stimulation in order to prevent irreversible vision loss in patients. This approach has the potential to help a large population of visually impaired individuals.
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Affiliation(s)
- Elvire Vaucher
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada.,Centre de recherche en neuropsychologie et cognition (CERNEC), Montréal, Québec, Canada
| | - Guillaume Laliberté
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada
| | - Marie-Charlotte Higgins
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada
| | - Manon Maheux
- Centre de recherche en neuropsychologie et cognition (CERNEC), Montréal, Québec, Canada.,Département de Psychologie, Université de Montréal, Montréal, Québec, Canada
| | - Pierre Jolicoeur
- Centre de recherche en neuropsychologie et cognition (CERNEC), Montréal, Québec, Canada.,Département de Psychologie, Université de Montréal, Montréal, Québec, Canada
| | - Mira Chamoun
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada
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Pruitt DT, Danaphongse TT, Lutchman M, Patel N, Reddy P, Wang V, Parashar A, Rennaker RL, Kilgard MP, Hays SA. Optimizing Dosing of Vagus Nerve Stimulation for Stroke Recovery. Transl Stroke Res 2020; 12:65-71. [PMID: 32583333 DOI: 10.1007/s12975-020-00829-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/27/2020] [Accepted: 06/14/2020] [Indexed: 12/14/2022]
Abstract
Vagus nerve stimulation (VNS) paired with rehabilitative training enhances recovery of function in models of stroke and is currently under investigation for use in chronic stroke patients. Dosing is critical in translation of pharmacological therapies, but electrical stimulation therapies often fail to comprehensively explore dosing parameters in preclinical studies. Varying VNS parameters has non-monotonic effects on plasticity in the central nervous system, which may directly impact efficacy for stroke. We sought to optimize stimulation intensity to maximize recovery of motor function in a model of ischemic stroke. The study design was preregistered prior to beginning data collection (DOI: https://doi.org/10.17605/OSF.IO/BMJEK ). After training on an automated assessment of forelimb function and receiving an ischemic lesion in motor cortex, rats were separated into groups that received rehabilitative training paired with VNS at distinct stimulation intensities (sham, 0.4 mA, 0.8 mA, or 1.6 mA). Moderate-intensity VNS at 0.8 mA enhanced recovery of function compared with all other groups. Neither 0.4 mA nor 1.6 mA VNS was sufficient to improve functional recovery compared with equivalent rehabilitation without VNS. These results demonstrate that moderate-intensity VNS delivered during rehabilitation improves recovery and defines an optimized intensity paradigm for clinical implementation of VNS therapy.
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Affiliation(s)
- David T Pruitt
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA.
| | - Tanya T Danaphongse
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA
| | - Megan Lutchman
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA
| | - Nishi Patel
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA
| | - Priyanka Reddy
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA
| | - Vanesse Wang
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA
| | - Anjana Parashar
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA
| | - Robert L Rennaker
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA.,Erik Jonsson School of Engineering and Computer Science, Richardson, TX, USA
| | - Michael P Kilgard
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA.,School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Seth A Hays
- Texas Biomedical Device Center, BSB11 800 W Campbell Rd, Richardson, TX, 75080, USA.,Erik Jonsson School of Engineering and Computer Science, Richardson, TX, USA
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46
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Morrison RA, Danaphongse TT, Pruitt DT, Adcock KS, Mathew JK, Abe ST, Abdulla DM, Rennaker RL, Kilgard MP, Hays SA. A limited range of vagus nerve stimulation intensities produce motor cortex reorganization when delivered during training. Behav Brain Res 2020; 391:112705. [PMID: 32473844 DOI: 10.1016/j.bbr.2020.112705] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 01/01/2023]
Abstract
Pairing vagus nerve stimulation (VNS) with rehabilitation has emerged as a potential strategy to improve recovery after neurological injury, an effect ascribed to VNS-dependent enhancement of synaptic plasticity. Previous studies demonstrate that pairing VNS with forelimb training increases forelimb movement representations in motor cortex. However, it is not known whether VNS-dependent enhancement of plasticity is restricted to forelimb training or whether VNS paired with other movements could induce plasticity of other motor representations. We tested the hypothesis that VNS paired with orofacial movements associated with chewing during an unskilled task would drive a specific increase in jaw representation in motor cortex compared to equivalent behavioral experience without VNS. Rats performed a behavioral task in which VNS at a specified intensity between 0 and 1.2 mA was paired with chewing 200 times per day for five days. Intracortical microstimulation (ICMS) was then used to document movement representations in motor cortex. VNS paired with chewing at 0.8 mA significantly increased motor cortex jaw representation compared to equivalent behavioral training without stimulation (Bonferroni-corrected unpaired t-test, p < 0.01). Higher and lower intensities failed to alter cortical plasticity. No changes in other movement representations or total motor cortex area were observed between groups. These results demonstrate that 0.8 mA VNS paired with training drives robust plasticity specific to the paired movement, is not restricted to forelimb representations, and occurs with training on an unskilled task. This suggests that moderate intensity VNS may be a useful adjuvant to enhance plasticity and support benefits of rehabilitative therapies targeting functions beyond upper limb movement.
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Affiliation(s)
- Robert A Morrison
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States.
| | - Tanya T Danaphongse
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - David T Pruitt
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Katherine S Adcock
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Jobin K Mathew
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Stephanie T Abe
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Dina M Abdulla
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Robert L Rennaker
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Michael P Kilgard
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States
| | - Seth A Hays
- The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Richardson, TX, United States
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47
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Identification of vagus nerve stimulation parameters affecting rat hippocampal electrophysiology without temperature effects. Brain Stimul 2020; 13:1198-1206. [PMID: 32454214 DOI: 10.1016/j.brs.2020.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/16/2020] [Accepted: 05/12/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Recent experiments in rats have demonstrated significant effects of VNS on hippocampal excitability but were partially attributed to hypothermia, induced by the applied VNS parameters. OBJECTIVE To allow meaningful preclinical research on the mechanisms of VNS and translation of rodent results to clinical VNS trials, we aimed to identify non-hypothermia inducing VNS parameters that significantly affect hippocampal excitability. METHODS VNS was administered in cycles of 30 s including either 0.1, 0.16, 0.25, 0.5, 1.5, 3 or 7 s of VNS ON time (biphasic pulses, 250μs/phase, 1 mA, 30 Hz) and the effect of different VNS ON times on brain temperature was evaluated. VNS paradigms with and without hypothermia were compared for their effects on hippocampal neurophysiology in freely moving rats. RESULTS Using VNS parameters with an ON time/OFF time of up to 0.5 s/30 s did not cause hypothermia, while clear hypothermia was detected with ON times of 1.5, 3 and 7 s/30 s. Relative to SHAM VNS, the normothermic 0.5 s VNS condition significantly decreased hippocampal EEG power and changed dentate gyrus evoked potentials with an increased field excitatory postsynaptic potential slope and a decreased population spike amplitude. CONCLUSION VNS can be administered in freely moving rats without causing hypothermia, while profoundly affecting hippocampal neurophysiology suggestive of reduced excitability of hippocampal neurons despite increased synaptic transmission efficiency.
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48
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Bucksot JE, Morales Castelan K, Skipton SK, Hays SA. Parametric characterization of the rat Hering-Breuer reflex evoked with implanted and non-invasive vagus nerve stimulation. Exp Neurol 2020; 327:113220. [PMID: 32027928 PMCID: PMC7089831 DOI: 10.1016/j.expneurol.2020.113220] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/01/2020] [Indexed: 12/17/2022]
Abstract
Vagus nerve stimulation (VNS) has rapidly gained interest as a treatment for a variety of disorders. A number of methods have been employed to stimulate the vagus nerve, but the most common relies on a cuff electrode implanted around the cervical branch of the nerve. Recently, two non-invasive methods have increased in popularity: transcutaneous cervical VNS (tcVNS) and transcutaneous auricular VNS (taVNS). Despite promising clinical results, there has been little direct comparison of these methods to stimulation delivered via an implanted device. In this study, we directly compared both non-invasive strategies to stimulation with an implanted cuff electrode on activation of the Hering-Breuer (HB) reflex, a non-invasive biomarker of A-fiber activation in the vagus. Stimulation was delivered across a wide range of parameters using tcVNS, taVNS, and an implanted cuff electrode in female rats. Activation of the HB reflex, changes in heart rate, and neck muscle twitch force were recorded. Consistent with low thresholds reported in previous studies, we found that the threshold to activate the HB reflex using an implanted cuff electrode was 0.406 ± 0.066 mA. tcVNS was capable of activating the HB reflex, but the threshold was 34.18 ± 1.86 mA, over 15 fold higher than the stimulation intensity that caused twitching of the neck muscles (2.09 ± 0.16 mA). No activation of the HB reflex was observed with taVNS at any parameters. These results describe activation of the HB reflex with each strategy and provide initial evidence regarding differences in the activation of the vagus nerve with invasive and non-invasive methods.
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Affiliation(s)
- Jesse E Bucksot
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Richardson, TX, United States of America.
| | - Karen Morales Castelan
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States of America
| | - Samantha K Skipton
- The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States of America
| | - Seth A Hays
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, Richardson, TX, United States of America; The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States of America; Texas Biomedical Device Center, Richardson, TX, United States of America
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49
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Souza RR, Robertson NM, Mathew E, Tabet MN, Bucksot JE, Pruitt DT, Rennaker RL, Hays SA, McIntyre CK, Kilgard MP. Efficient parameters of vagus nerve stimulation to enhance extinction learning in an extinction-resistant rat model of PTSD. Prog Neuropsychopharmacol Biol Psychiatry 2020; 99:109848. [PMID: 31863872 DOI: 10.1016/j.pnpbp.2019.109848] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 12/20/2022]
Abstract
Vagus nerve stimulation (VNS) has shown promise as an adjuvant treatment for posttraumatic stress disorder (PTSD), as it enhances fear extinction and reduces anxiety symptoms in multiple rat models of this condition. Yet, identification of the optimal stimulation paradigm is needed to facilitate clinical translation of this potential therapy. Using an extinction-resistant rat model of PTSD, we tested whether varying VNS intensity and duration could maximize extinction learning while minimizing the total amount of stimulation. We confirmed that sham rats failed to extinguish after a week of extinction training. Delivery of the standard LONG VNS trains (30 s) at 0.4 mA enhanced extinction and reduced anxiety but did not prevent fear return. Increasing the intensity of LONG VNS trains to 0.8 mA prevented fear return and attenuated anxiety symptoms. Interestingly, delivering 1, 4 or 16 SHORT VNS bursts (0.5 s) at 0.8 mA during each cue presentation in extinction training also enhanced extinction. LONG VNS trains or multiple SHORT VNS bursts at 0.8 mA attenuated fear renewal and reinstatement, promoted extinction generalization and reduced generalized anxiety. Delivering 16 SHORT VNS bursts also facilitated extinction in fewer trials. This study provides the first evidence that brief bursts of VNS can enhance extinction training, reduce relapse and support symptom remission using much less VNS than previous protocols. These findings suggest that VNS parameters can be adjusted in order to minimize total charge delivery and maximize therapeutic effectiveness.
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Affiliation(s)
- Rimenez R Souza
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America.
| | - Nicole M Robertson
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - Ezek Mathew
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - Michel N Tabet
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - Jesse E Bucksot
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - David T Pruitt
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - Robert L Rennaker
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - Seth A Hays
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - Christa K McIntyre
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
| | - Michael P Kilgard
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States of America
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50
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Mathew E, Tabet MN, Robertson NM, Hays SA, Rennaker RL, Kilgard MP, McIntyre CK, Souza RR. Vagus nerve stimulation produces immediate dose-dependent anxiolytic effect in rats. J Affect Disord 2020; 265:552-557. [PMID: 31784117 DOI: 10.1016/j.jad.2019.11.090] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/20/2019] [Accepted: 11/12/2019] [Indexed: 01/18/2023]
Abstract
BACKGROUND Chronic vagus nerve stimulation (VNS) attenuates anxiety in rats and humans. However, it is unclear whether VNS can promote acute anxiolytic effects. Here we examined short-term anxiolytic effects of VNS using single or multiple trains in rats submitted to a battery of tests. METHODS Three groups of rats were implanted with VNS cuffs and tested for anxiety using the elevated plus maze (EPM), novelty suppressed feeding (NSF), and acoustic startle response (ASR), after receiving either one or five VNS trains (0.4 mA/30 Hz/30‑sec), or sham stimulation. RESULTS Both single and multiple VNS trains reduced state anxiety as measured using the EPM, but only multiple trains reduced anxiety in the EPM and NSF. VNS did not decrease arousal as measured using the ASR. LIMITATIONS The anxiolytic effects of VNS may be differently influenced by test order or prior-exposure to stress. VNS did not affect startle responses in naïve rats but the present findings do not determine whether VNS would affect startle responses that are potentiated by fear or anxiety. CONCLUSION A single VNS train can produce an anxiolytic-like effect in the EPM minutes later, an effect that is not observed in the NSF. Delivering 5 VNS trains restores the immediate effects across tests of anxiety, indicating that more trains produce a more robust anxiolytic effect. The lack of effects on ASR suggests that VNS affects state anxiety but not baseline arousal in naïve rats. We suggest that the anxiolytic effect of VNS can increase tolerability and reduce dropout in exposure-based therapies.
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Affiliation(s)
- Ezek Mathew
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Michel N Tabet
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Nicole M Robertson
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Seth A Hays
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Robert L Rennaker
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Michael P Kilgard
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Christa K McIntyre
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States
| | - Rimenez R Souza
- Texas Biomedical Device Center, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States; School of Behavioral Brain Sciences, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, United States.
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