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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Ruiz AD, Malley KM, Danaphongse TT, Ahmad FN, Beltran CM, White ML, Baghdadi S, Pruitt DT, Rennaker RL, Kilgard MP, Hays SA. Vagus Nerve Stimulation Must Occur During Tactile Rehabilitation to Enhance Somatosensory Recovery. Neuroscience 2023; 532:79-86. [PMID: 37778688 DOI: 10.1016/j.neuroscience.2023.09.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Chronic sensory loss is a common and undertreated consequence of many forms of neurological injury. Emerging evidence indicates that vagus nerve stimulation (VNS) delivered during tactile rehabilitation promotes recovery of somatosensation. Here, we systematically varied the timing of VNS relative to tactile rehabilitation to determine the paradigm that yields the greatest degree of somatosensory recovery after peripheral nerve injury (PNI). The medial and ulnar nerves in rats were transected, causing chronic sensory loss. Eight weeks after injury, rats were given a VNS implant followed by four weeks of tactile rehabilitation sessions consisting of repeated mechanical stimuli to the previously denervated forepaw. Rats received VNS before, during, or after tactile rehabilitation. Delivery of VNS during rehabilitative training generates robust, significant recovery compared to rehabilitative training without stimulation (56 ± 14% improvement over sham stimulation). A matched amount of VNS before training, immediately after training, or two hours after training is significantly less effective than VNS during rehabilitative training and fails to improve recovery compared to rehabilitative training alone (5 ± 10%, 4 ± 11%, and -7 ± 22% improvement over sham stimulation, respectively). These findings indicate that concurrent delivery of VNS during rehabilitative training is most effective and illustrate the importance of considering stimulation timing for clinical implementation of VNS therapy.
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Affiliation(s)
- Andrea D Ruiz
- 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.
| | - Kaitlyn M Malley
- 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
| | - Tanya T Danaphongse
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, USA
| | - Fatima N Ahmad
- 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
| | - Clareth Mota Beltran
- 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
| | - Megan L White
- 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
| | - Sahba Baghdadi
- 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
| | - David T Pruitt
- Texas Biomedical Device Center, 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; Erik Jonsson School of Engineering and Computer Science, 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
| | - 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; School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, USA
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Ruiz AD, Malley KM, Danaphongse TT, Ahmad FN, Mota Beltran C, Rennaker RL, Kilgard MP, Hays SA. Effective Delivery of Vagus Nerve Stimulation Requires Many Stimulations Per Session and Many Sessions Per Week Over Many Weeks to Improve Recovery of Somatosensation. Neurorehabil Neural Repair 2023; 37:652-661. [PMID: 37694568 PMCID: PMC10523825 DOI: 10.1177/15459683231197412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
BACKGROUND Chronic sensory loss is a common and undertreated consequence of many forms of neurological injury. Emerging evidence indicates that vagus nerve stimulation (VNS) delivered during tactile rehabilitation promotes recovery of somatosensation. OBJECTIVE Here, we characterize the amount, intensity, frequency, and duration of VNS therapy paradigms to determine the optimal dosage for VNS-dependent enhancement of recovery in a model of peripheral nerve injury (PNI). METHODS Rats underwent transection of the medial and ulnar nerves in the forelimb, resulting in chronic sensory loss in the paw. Eight weeks after injury, rats were implanted with a VNS cuff and received tactile rehabilitation sessions consisting of repeated mechanical stimulation of the previously denervated forepaw paired with short bursts of VNS. Rats received VNS therapy in 1 of 6 systematically varied dosing schedules to identify a paradigm that balanced therapy effectiveness with a shorter regimen. RESULTS Delivering 200 VNS pairings a day 4 days a week for 4 weeks produced the greatest percent improvement in somatosensory function compared to any of the 6 other groups (One Way analysis of variance at the end of therapy, F[4 70] P = .005). CONCLUSIONS Our findings demonstrate that an effective VNS therapy dosage delivers many stimulations per session, with many sessions per week, over many weeks. These results provide a framework to inform the development of VNS-based therapies for sensory restoration.
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Affiliation(s)
- Andrea D. Ruiz
- 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
| | - Kaitlyn M. Malley
- 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
| | - Tanya T. Danaphongse
- Texas Biomedical Device Center, The University of Texas at Dallas, Richardson, TX, USA
| | - Fatima N. Ahmad
- 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
| | - Clareth Mota Beltran
- 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
| | - Robert L. Rennaker
- 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
- 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
| | - 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
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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: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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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: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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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: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Darrow MJ, Torres M, Sosa MJ, Danaphongse TT, Haider Z, Rennaker RL, Kilgard MP, Hays SA. Vagus Nerve Stimulation Paired With Rehabilitative Training Enhances Motor Recovery After Bilateral Spinal Cord Injury to Cervical Forelimb Motor Pools. Neurorehabil Neural Repair 2020; 34:200-209. [PMID: 31969052 DOI: 10.1177/1545968319895480] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Closed-loop vagus nerve stimulation (VNS) paired with rehabilitative training has emerged as a strategy to enhance recovery after neurological injury. Previous studies demonstrate that brief bursts of closed-loop VNS paired with rehabilitative training substantially improve recovery of forelimb motor function in models of unilateral and bilateral contusive spinal cord injury (SCI) at spinal level C5/6. While these findings provide initial evidence of the utility of VNS for SCI, the injury model used in these studies spares the majority of alpha motor neurons originating in C7-T1 that innervate distal forelimb muscles. Because the clinical manifestation of SCI in many patients involves damage at these levels, it is important to define whether damage to the distal forelimb motor neuron pools limits VNS-dependent recovery. In this study, we assessed recovery of forelimb function in rats that received a bilateral incomplete contusive SCI at C7/8 and underwent extensive rehabilitative training with or without paired VNS. The study design, including planned sample size, assessments, and statistical comparisons, was preregistered prior to beginning data collection ( https://osf.io/ysvgf/ ). VNS paired with rehabilitative training significantly improved recovery of volitional forelimb strength compared to equivalent rehabilitative training without VNS. Additionally, VNS-dependent enhancement of recovery generalized to 2 similar, but untrained, forelimb tasks. These findings indicate that damage to alpha motor neurons does not prevent VNS-dependent enhancement of recovery and provides additional evidence to support the evaluation of closed-loop VNS paired with rehabilitation in patients with incomplete cervical SCI.
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Affiliation(s)
| | | | - Maria J Sosa
- The University of Texas at Dallas, Richardson, TX, USA
| | | | - Zainab Haider
- The University of Texas at Dallas, Richardson, TX, USA
| | | | | | - Seth A Hays
- The University of Texas at Dallas, Richardson, TX, USA
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Pruitt DT, Danaphongse TT, Schmid AN, Morrison RA, Kilgard MP, Rennaker RL, Hays SA. Traumatic Brain Injury Occludes Training-Dependent Cortical Reorganization in the Contralesional Hemisphere. J Neurotrauma 2017; 34:2495-2503. [PMID: 28462608 DOI: 10.1089/neu.2016.4796] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rehabilitative training drives plasticity in the ipsilesional (injured) motor cortex that is believed to support recovery of motor function after either stroke or traumatic brain injury (TBI). In addition, adaptive plasticity in the contralesional (uninjured) motor cortex has been well-characterized in the context of stroke. While similar rehabilitation-dependent plasticity in the intact hemisphere may occur after TBI, this has yet to be thoroughly explored. In this study, we investigated the effects of TBI and forelimb training on reorganization of movement representations in the intact motor cortex. Rats were trained to proficiency on the isometric pull task and then received a controlled cortical impact (CCI) in the left motor cortex to impair function of the trained right forelimb. After TBI, animals underwent forelimb training on the pull task for 2 months. At the end of training, intracortical microstimulation was used to document the organization of the intact motor cortex (the contralesional hemisphere). TBI significantly decreased the cortical area eliciting movements of the impaired forelimb in untrained animals. In the absence of TBI, training significantly increased forelimb map area, compared with in untrained controls. However, training of the impaired forelimb after TBI was insufficient to increase forelimb map area. These findings are consistent with other studies showing impaired rehabilitation-dependent plasticity after TBI and provide a novel characterization of TBI on rehabilitation-dependent plasticity in contralesional motor circuits.
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Affiliation(s)
- David T Pruitt
- 1 School of Behavioral Brain Sciences University of Texas at Dallas , Richardson, Texas.,2 Erik Jonsson School of Engineering and Computer Science University of Texas at Dallas , Richardson, Texas.,3 Texas Biomedical Device Center, University of Texas at Dallas , Richardson, Texas
| | - Tanya T Danaphongse
- 1 School of Behavioral Brain Sciences University of Texas at Dallas , Richardson, Texas.,2 Erik Jonsson School of Engineering and Computer Science University of Texas at Dallas , Richardson, Texas.,3 Texas Biomedical Device Center, University of Texas at Dallas , Richardson, Texas
| | - Ariel N Schmid
- 1 School of Behavioral Brain Sciences University of Texas at Dallas , Richardson, Texas.,3 Texas Biomedical Device Center, University of Texas at Dallas , Richardson, Texas
| | - Robert A Morrison
- 1 School of Behavioral Brain Sciences University of Texas at Dallas , Richardson, Texas.,3 Texas Biomedical Device Center, University of Texas at Dallas , Richardson, Texas
| | - Michael P Kilgard
- 1 School of Behavioral Brain Sciences University of Texas at Dallas , Richardson, Texas.,3 Texas Biomedical Device Center, University of Texas at Dallas , Richardson, Texas
| | - Robert L Rennaker
- 1 School of Behavioral Brain Sciences University of Texas at Dallas , Richardson, Texas.,2 Erik Jonsson School of Engineering and Computer Science University of Texas at Dallas , Richardson, Texas.,3 Texas Biomedical Device Center, University of Texas at Dallas , Richardson, Texas
| | - Seth A Hays
- 2 Erik Jonsson School of Engineering and Computer Science University of Texas at Dallas , Richardson, Texas.,3 Texas Biomedical Device Center, University of Texas at Dallas , Richardson, Texas
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Pruitt DT, Schmid AN, Danaphongse TT, Flanagan KE, Morrison RA, Kilgard MP, Rennaker RL, Hays SA. Forelimb training drives transient map reorganization in ipsilateral motor cortex. Behav Brain Res 2016; 313:10-16. [PMID: 27392641 DOI: 10.1016/j.bbr.2016.07.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/06/2016] [Accepted: 07/04/2016] [Indexed: 01/01/2023]
Abstract
Skilled motor training results in reorganization of contralateral motor cortex movement representations. The ipsilateral motor cortex is believed to play a role in skilled motor control, but little is known about how training influences reorganization of ipsilateral motor representations of the trained limb. To determine whether training results in reorganization of ipsilateral motor cortex maps, rats were trained to perform the isometric pull task, an automated motor task that requires skilled forelimb use. After either 3 or 6 months of training, intracortical microstimulation (ICMS) mapping was performed to document motor representations of the trained forelimb in the hemisphere ipsilateral to that limb. Motor training for 3 months resulted in a robust expansion of right forelimb representation in the right motor cortex, demonstrating that skilled motor training drives map plasticity ipsilateral to the trained limb. After 6 months of training, the right forelimb representation in the right motor cortex was significantly smaller than the representation observed in rats trained for 3 months and similar to untrained controls, consistent with a normalization of motor cortex maps. Forelimb map area was not correlated with performance on the trained task, suggesting that task performance is maintained despite normalization of cortical maps. This study provides new insights into how the ipsilateral cortex changes in response to skilled learning and may inform rehabilitative strategies to enhance cortical plasticity to support recovery after brain injury.
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Affiliation(s)
- David T Pruitt
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States.
| | - Ariel N Schmid
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Tanya T Danaphongse
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Kate E Flanagan
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Robert A Morrison
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Michael P Kilgard
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; 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, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Seth A Hays
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
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