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Décarie-Spain L, Hayes AMR, Lauer LT, Kanoski SE. The gut-brain axis and cognitive control: A role for the vagus nerve. Semin Cell Dev Biol 2024; 156:201-209. [PMID: 36803834 PMCID: PMC10427741 DOI: 10.1016/j.semcdb.2023.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 02/07/2023] [Indexed: 02/18/2023]
Abstract
Survival requires the integration of external information and interoceptive cues to effectively guide advantageous behaviors, particularly foraging and other behaviors that promote energy acquisition and consumption. The vagus nerve acts as a critical relay between the abdominal viscera and the brain to convey metabolic signals. This review synthesizes recent findings from rodent models and humans revealing the impact of vagus nerve signaling from the gut on the control of higher-order neurocognitive domains, including anxiety, depression, reward motivation, and learning and memory. We propose a framework where meal consumption engages gastrointestinal tract-originating vagal afferent signaling that functions to alleviate anxiety and depressive-like states, while also promoting motivational and memory functions. These concurrent processes serve to favor the encoding of meal-relevant information into memory storage, thus facilitating future foraging behaviors. Modulation of these neurocognitive domains by vagal tone is also discussed in the context of pathological conditions, including the use of transcutaneous vagus nerve stimulation for the treatment of anxiety disorders, major depressive disorder, and dementia-associated memory impairments. Collectively, these findings highlight the contributions of gastrointestinal vagus nerve signaling to the regulation of neurocognitive processes that shape various adaptive behavioral responses.
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Affiliation(s)
- Léa Décarie-Spain
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, 3616 Trousdale Pkwy, Los Angeles, CA 90089, USA
| | - Anna M R Hayes
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, 3616 Trousdale Pkwy, Los Angeles, CA 90089, USA
| | - Logan Tierno Lauer
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, 3616 Trousdale Pkwy, Los Angeles, CA 90089, USA
| | - Scott E Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, 3616 Trousdale Pkwy, Los Angeles, CA 90089, USA; Neuroscience Graduate Program, University of Southern California, 3641Watt Way, Los Angeles, CA 90089, USA.
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2
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Jigo M, Carmel JB, Wang Q, Rodenkirch C. Transcutaneous cervical vagus nerve stimulation improves sensory performance in humans: a randomized controlled crossover pilot study. Sci Rep 2024; 14:3975. [PMID: 38368486 PMCID: PMC10874458 DOI: 10.1038/s41598-024-54026-8] [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: 08/17/2023] [Accepted: 02/07/2024] [Indexed: 02/19/2024] Open
Abstract
Accurate senses depend on high-fidelity encoding by sensory receptors and error-free processing in the brain. Progress has been made towards restoring damaged sensory receptors. However, methods for on-demand treatment of impaired central sensory processing are scarce. Prior invasive studies demonstrated that continuous vagus nerve stimulation (VNS) in rodents can activate the locus coeruleus-norepinephrine system to rapidly improve central sensory processing. Here, we investigated whether transcutaneous VNS improves sensory performance in humans. We conducted three sham-controlled experiments, each with 12 neurotypical adults, that measured the effects of transcutaneous VNS on metrics of auditory and visual performance, and heart rate variability (HRV). Continuous stimulation was delivered to cervical (tcVNS) or auricular (taVNS) branches of the vagus nerve while participants performed psychophysics tasks or passively viewed a display. Relative to sham stimulation, tcVNS improved auditory performance by 37% (p = 0.00052) and visual performance by 23% (p = 0.038). Participants with lower performance during sham conditions experienced larger tcVNS-evoked improvements (p = 0.0040). Lastly, tcVNS increased HRV during passive viewing, corroborating vagal engagement. No evidence for an effect of taVNS was observed. These findings validate the effectiveness of tcVNS in humans and position it as a method for on-demand interventions of impairments associated with central sensory processing dysfunction.
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Affiliation(s)
| | - Jason B Carmel
- Sharper Sense, Inc., New York, NY, USA
- Department of Neurology and Orthopedics, Columbia University Medical Center, New York, NY, USA
| | - Qi Wang
- Sharper Sense, Inc., New York, NY, USA
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Charles Rodenkirch
- Sharper Sense, Inc., New York, NY, USA.
- The Jacobs Technion-Cornell Institute at Cornell Tech, New York, NY, USA.
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3
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Jigo M, Carmel JB, Wang Q, Rodenkirch C. Transcutaneous cervical vagus nerve stimulation improves sensory performance in humans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.08.552508. [PMID: 37609169 PMCID: PMC10441305 DOI: 10.1101/2023.08.08.552508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Accurate senses depend on high-fidelity encoding by sensory receptors and error-free processing in the brain. Progress has been made towards restoring damaged sensory receptors. However, methods for on-demand treatment of impaired central sensory processing are scarce. Prior invasive studies demonstrated that continuous vagus nerve stimulation (VNS) in rodents can activate the locus coeruleus-norepinephrine system to rapidly improve central sensory processing. Here, we investigated whether transcutaneous VNS improves sensory performance in humans. We conducted three sham-controlled experiments, each with 12 neurotypical adults, that measured the effects of transcutaneous VNS on metrics of auditory and visual performance, and heart rate variability (HRV). Continuous stimulation was delivered to cervical (tcVNS) or auricular (taVNS) branches of the vagus nerve while participants performed psychophysics tasks or passively viewed a display. Relative to sham stimulation, tcVNS improved auditory performance by 37% (p=0.00052) and visual performance by 23% (p=0.038). Participants with lower performance during sham conditions experienced larger tcVNS-evoked improvements (p=0.0040). Lastly, tcVNS increased HRV during passive viewing, corroborating vagal engagement. No evidence for an effect of taVNS was observed. These findings validate the effectiveness of tcVNS in humans and position it as a method for on-demand interventions of impairments associated with central sensory processing dysfunction.
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Affiliation(s)
| | - Jason B. Carmel
- Sharper Sense, Inc., New York, NY
- Department of Neurology and Orthopedics, Columbia University Medical Center, New York, NY
| | - Qi Wang
- Sharper Sense, Inc., New York, NY
- Department of Biomedical Engineering, Columbia University, New York, NY
| | - Charles Rodenkirch
- Sharper Sense, Inc., New York, NY
- The Jacobs Technion-Cornell Institute at Cornell Tech, New York, NY
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4
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Johns MA, Calloway RC, Karunathilake IMD, Decruy LP, Anderson S, Simon JZ, Kuchinsky SE. Attention Mobilization as a Modulator of Listening Effort: Evidence From Pupillometry. Trends Hear 2024; 28:23312165241245240. [PMID: 38613337 PMCID: PMC11015766 DOI: 10.1177/23312165241245240] [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: 07/21/2023] [Revised: 03/11/2024] [Accepted: 03/15/2024] [Indexed: 04/14/2024] Open
Abstract
Listening to speech in noise can require substantial mental effort, even among younger normal-hearing adults. The task-evoked pupil response (TEPR) has been shown to track the increased effort exerted to recognize words or sentences in increasing noise. However, few studies have examined the trajectory of listening effort across longer, more natural, stretches of speech, or the extent to which expectations about upcoming listening difficulty modulate the TEPR. Seventeen younger normal-hearing adults listened to 60-s-long audiobook passages, repeated three times in a row, at two different signal-to-noise ratios (SNRs) while pupil size was recorded. There was a significant interaction between SNR, repetition, and baseline pupil size on sustained listening effort. At lower baseline pupil sizes, potentially reflecting lower attention mobilization, TEPRs were more sustained in the harder SNR condition, particularly when attention mobilization remained low by the third presentation. At intermediate baseline pupil sizes, differences between conditions were largely absent, suggesting these listeners had optimally mobilized their attention for both SNRs. Lastly, at higher baseline pupil sizes, potentially reflecting overmobilization of attention, the effect of SNR was initially reversed for the second and third presentations: participants initially appeared to disengage in the harder SNR condition, resulting in reduced TEPRs that recovered in the second half of the story. Together, these findings suggest that the unfolding of listening effort over time depends critically on the extent to which individuals have successfully mobilized their attention in anticipation of difficult listening conditions.
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Affiliation(s)
- M. A. Johns
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA
| | - R. C. Calloway
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA
| | - I. M. D. Karunathilake
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, USA
| | - L. P. Decruy
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA
| | - S. Anderson
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD 20742, USA
| | - J. Z. Simon
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, USA
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - S. E. Kuchinsky
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD 20742, USA
- National Military Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, MD 20889, 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: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [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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Kuchinsky SE, Razeghi N, Pandža NB. Auditory, Lexical, and Multitasking Demands Interactively Impact Listening Effort. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2023; 66:4066-4082. [PMID: 37672797 PMCID: PMC10713022 DOI: 10.1044/2023_jslhr-22-00548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 03/12/2023] [Accepted: 06/27/2023] [Indexed: 09/08/2023]
Abstract
PURPOSE This study examined the extent to which acoustic, linguistic, and cognitive task demands interactively impact listening effort. METHOD Using a dual-task paradigm, on each trial, participants were instructed to perform either a single task or two tasks. In the primary word recognition task, participants repeated Northwestern University Auditory Test No. 6 words presented in speech-shaped noise at either an easier or a harder signal-to-noise ratio (SNR). The words varied in how commonly they occur in the English language (lexical frequency). In the secondary visual task, participants were instructed to press a specific key as soon as a number appeared on screen (simpler task) or one of two keys to indicate whether the visualized number was even or odd (more complex task). RESULTS Manipulation checks revealed that key assumptions of the dual-task design were met. A significant three-way interaction was observed, such that the expected effect of SNR on effort was only observable for words with lower lexical frequency and only when multitasking demands were relatively simpler. CONCLUSIONS This work reveals that variability across speech stimuli can influence the sensitivity of the dual-task paradigm for detecting changes in listening effort. In line with previous work, the results of this study also suggest that higher cognitive demands may limit the ability to detect expected effects of SNR on measures of effort. With implications for real-world listening, these findings highlight that even relatively minor changes in lexical and multitasking demands can alter the effort devoted to listening in noise.
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Affiliation(s)
- Stefanie E. Kuchinsky
- Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, MD
- Applied Research Laboratory for Intelligence and Security, University of Maryland, College Park
- Department of Hearing and Speech Sciences, University of Maryland, College Park
| | - Niki Razeghi
- Department of Hearing and Speech Sciences, University of Maryland, College Park
| | - Nick B. Pandža
- Applied Research Laboratory for Intelligence and Security, University of Maryland, College Park
- Program in Second Language Acquisition, University of Maryland, College Park
- Maryland Language Science Center, University of Maryland, College Park
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Cansler R, Heidrich J, Whiting A, Tran D, Hall P, Tyler WJ. Influence of CrossFit and Deep End Fitness training on mental health and coping in athletes. Front Sports Act Living 2023; 5:1061492. [PMID: 37849685 PMCID: PMC10577405 DOI: 10.3389/fspor.2023.1061492] [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: 10/04/2022] [Accepted: 09/19/2023] [Indexed: 10/19/2023] Open
Abstract
Physical exercise is known to improve mental health. Athletes can experience unique physical and emotional stressors, which can deteriorate mental health and cognitive function. Training apathy can lead to cognitive dissonance and further degrade performance by promoting maladaptive, avoidance coping strategies. Introduction of psychosocial and training variables, such as those used in CrossFit (CF) and other community-based fitness programs with strong peer support have been shown to help reduce training apathy and negative affect. Here, we explored whether addition of psychophysiological variation, experienced as "hunger for air" during underwater breath-hold exercises, could provide unique mental health benefits for athletes. We studied the influence of CF and Deep End Fitness (DEF), a community-based underwater fitness program, on several outcome measures of mental health and emotional well-being in volunteer athletes. We observed a significant reduction in stress scores of both the control CF training group and the experimental DEF group. We found that DEF produced a significant improvement in positive affect while CF training did not. Further supportive of our hypothesis that the psychological and biological stressors experienced in underwater, breath-hold training cause positive adaptive changes and benefits, DEF training uniquely increased problem-based coping. While our observations demonstrate both CF and DEF training can improve mental health in athletes, DEF produced additional, unique benefits to positive coping and attitudes of athletes. Future studies should further evaluate the broader benefits of community-based, underwater training programs on psychological and physiological health in athletes and the public.
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Affiliation(s)
- Rachel Cansler
- Department of Psychology, New York University, New York, NY, United States
- Deep End Fitness, San Diego, CA, United States
| | | | - Ali Whiting
- Deep End Fitness, San Diego, CA, United States
| | - Don Tran
- Deep End Fitness, San Diego, CA, United States
| | - Prime Hall
- Deep End Fitness, San Diego, CA, United States
| | - William J. Tyler
- Deep End Fitness, San Diego, CA, United States
- IST, LLC, Birmingham, AL, United States
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Gianlorenco ACL, de Melo PS, Marduy A, Kim AY, Kim CK, Choi H, Song JJ, Fregni F. Electroencephalographic Patterns in taVNS: A Systematic Review. Biomedicines 2022; 10:2208. [PMID: 36140309 PMCID: PMC9496216 DOI: 10.3390/biomedicines10092208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/24/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022] Open
Abstract
Transcutaneous auricular vagus nerve stimulation (taVNS) is a newer delivery system using a non-invasive stimulation device placed at the ear. taVNS research is focused on clinical trials showing potential therapeutic benefits, however the neurophysiological effects of this stimulation on brain activity are still unclear. We propose a systematic review that aims to describe the effects of taVNS on EEG measures and identify taVNS parameters that can potentially lead to consistent EEG-mediated biomarkers for this therapy. A systematic literature review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) and the Cochrane handbook for systematic reviews. Clinical trials examining EEG parameters were considered, including absolute and relative power, coherence, degree of symmetry, evoked potentials, and peak frequency of all bands. According to our criteria, 18 studies (from 122 articles) were included. Our findings show a general trend towards increased EEG power spectrum activity in lower frequencies, and changes on early components of the ERP related to inhibitory tasks. This review suggests that quantitative electroencephalography can be used to assess the effects of taVNS on brain activity, however more studies are needed to systematically establish the specific effects and metrics that would reflect the non-invasive stimulation through the auricular branch of the vagus nerve.
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Affiliation(s)
- Anna Carolyna L. Gianlorenco
- Department of Physical Therapy, Federal University of Sao Carlos, Sao Carlos 13565-090, Brazil
- Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA
| | - Paulo S. de Melo
- Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA
- Medicine, Escola Bahiana de Medicina e Saúde Pública, Salvador 40290-000, Brazil
| | - Anna Marduy
- Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA
- União Metropolitana de Ensino e Cultura (UNIME) Salvador, Salvador 42700-000, Brazil
| | - Angela Yun Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University Medical Center, Seoul 08308, Korea
| | - Chi Kyung Kim
- Department of Neurology, Korea University Guro Hospital, Seoul 08308, Korea
| | - Hyuk Choi
- Department of Medical Sciences, Graduate School of Medicine, Korea University, Seoul 08308, Korea
- Neurive Co., Ltd., Gimhae 08308, Korea
| | - Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University Medical Center, Seoul 08308, Korea
- Neurive Co., Ltd., Gimhae 08308, Korea
| | - Felipe Fregni
- Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA
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Rodenkirch C, Carmel JB, Wang Q. Rapid Effects of Vagus Nerve Stimulation on Sensory Processing Through Activation of Neuromodulatory Systems. Front Neurosci 2022; 16:922424. [PMID: 35864985 PMCID: PMC9294458 DOI: 10.3389/fnins.2022.922424] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 06/15/2022] [Indexed: 12/13/2022] Open
Abstract
After sensory information is encoded into neural signals at the periphery, it is processed through multiple brain regions before perception occurs (i.e., sensory processing). Recent work has begun to tease apart how neuromodulatory systems influence sensory processing. Vagus nerve stimulation (VNS) is well-known as an effective and safe method of activating neuromodulatory systems. There is a growing body of studies confirming VNS has immediate effects on sensory processing across multiple sensory modalities. These immediate effects of VNS on sensory processing are distinct from the more well-documented method of inducing lasting neuroplastic changes to the sensory pathways through repeatedly delivering a brief VNS burst paired with a sensory stimulus. Immediate effects occur upon VNS onset, often disappear upon VNS offset, and the modulation is present for all sensory stimuli. Conversely, the neuroplastic effect of pairing sub-second bursts of VNS with a sensory stimulus alters sensory processing only after multiple pairing sessions, this alteration remains after cessation of pairing sessions, and the alteration selectively affects the response properties of neurons encoding the specific paired sensory stimulus. Here, we call attention to the immediate effects VNS has on sensory processing. This review discusses existing studies on this topic, provides an overview of the underlying neuromodulatory systems that likely play a role, and briefly explores the potential translational applications of using VNS to rapidly regulate sensory processing.
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Affiliation(s)
- Charles Rodenkirch
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
- Jacobs Technion-Cornell Institute, Cornell Tech, New York, NY, United States
- *Correspondence: Charles Rodenkirch,
| | - Jason B. Carmel
- Department of Neurology and Orthopedics, Columbia University Medical Center, New York, NY, United States
| | - Qi Wang
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
- Qi Wang,
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10
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Abstract
The human brain exhibits the remarkable ability to categorize speech sounds into distinct, meaningful percepts, even in challenging tasks like learning non-native speech categories in adulthood and hearing speech in noisy listening conditions. In these scenarios, there is substantial variability in perception and behavior, both across individual listeners and individual trials. While there has been extensive work characterizing stimulus-related and contextual factors that contribute to variability, recent advances in neuroscience are beginning to shed light on another potential source of variability that has not been explored in speech processing. Specifically, there are task-independent, moment-to-moment variations in neural activity in broadly-distributed cortical and subcortical networks that affect how a stimulus is perceived on a trial-by-trial basis. In this review, we discuss factors that affect speech sound learning and moment-to-moment variability in perception, particularly arousal states—neurotransmitter-dependent modulations of cortical activity. We propose that a more complete model of speech perception and learning should incorporate subcortically-mediated arousal states that alter behavior in ways that are distinct from, yet complementary to, top-down cognitive modulations. Finally, we discuss a novel neuromodulation technique, transcutaneous auricular vagus nerve stimulation (taVNS), which is particularly well-suited to investigating causal relationships between arousal mechanisms and performance in a variety of perceptual tasks. Together, these approaches provide novel testable hypotheses for explaining variability in classically challenging tasks, including non-native speech sound learning.
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