Tragus

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 1683 Experts worldwide ranked by ideXlab platform

Jim Deuchars - One of the best experts on this subject based on the ideXlab platform.

  • cardiovascular autonomic effects of transcutaneous auricular nerve stimulation via the Tragus in the rat involve spinal cervical sensory afferent pathways
    Brain Stimulation, 2019
    Co-Authors: Km Mahadi, Sa Deuchars, Varinder K Lall, Jim Deuchars
    Abstract:

    Abstract Background Electrical stimulation on select areas of the external auricular dermatome influences the autonomic nervous system. It has been postulated that activation of the Auricular Branch of the Vagus Nerve (ABVN) mediates such autonomic changes. However, the underlying neural pathways mediating these effects are unknown and, further, our understanding of the anatomical distribution of the ABVN in the auricle has now been questioned. Objective To investigate the effects of electrical stimulation of the Tragus on autonomic outputs in the rat and probe the underlying neural pathways. Methods Central neuronal projections from nerves innervating the external auricle were investigated by injections of the transganglionic tracer cholera toxin B chain (CTB) into the right Tragus of Wistar rats. Physiological recordings of heart rate, perfusion pressure, respiratory rate and sympathetic nerve activity were made in an anaesthetic free Working Heart Brainstem Preparation (WHBP) of the rat and changes in response to electrical stimulation of the Tragus analysed. Results Neuronal tracing from the Tragus revealed that the densest CTB labelling was within laminae III-IV of the dorsal horn of the upper cervical spinal cord, ipsilateral to the injection sites. In the medulla oblongata, CTB labelled afferents were observed in the paratrigeminal nucleus, spinal trigeminal tract and cuneate nucleus. Surprisingly, only sparse labelling was observed in the vagal afferent termination site, the nucleus tractus solitarius. Recordings made from rats at night time revealed more robust sympathetic activity in comparison to day time rats, thus subsequent experiments were conducted in rats at night time. Electrical stimulation was delivered across the Tragus for 5 min. Direct recording from the sympathetic chain revealed a central sympathoinhibition by up to 36% following Tragus stimulation. Sympathoinhibition remained following sectioning of the cervical vagus nerve ipsilateral to the stimulation site, but was attenuated by sectioning of the upper cervical afferent nerve roots. Conclusions Inhibition of the sympathetic nervous system activity upon electrical stimulation of the Tragus in the rat is mediated at least in part through sensory afferent projections to the upper cervical spinal cord. This challenges the notion that tragal stimulation is mediated by the auricular branch of the vagus nerve and suggests that alternative mechanisms may be involved.

Stavros Stavrakis - One of the best experts on this subject based on the ideXlab platform.

  • low level Tragus stimulation modulates atrial alternans and fibrillation burden in patients with paroxysmal atrial fibrillation
    Journal of the American Heart Association, 2021
    Co-Authors: Kanchan Kulkarni, Stavros Stavrakis, Jagmeet P Singh, Kimberly A Parks, Demosthenes G Katritsis, Antonis A Armoundas
    Abstract:

    Background Low‐level Tragus stimulation (LLTS) has been shown to significantly reduce atrial fibrillation (AF) burden in patients with paroxysmal AF. P‐wave alternans (PWA) is believed to be genera...

  • low level transcutaneous electrical stimulation of the auricular branch of the vagus nerve a noninvasive approach to treat the initial phase of atrial fibrillation
    Heart Rhythm, 2013
    Co-Authors: Benjamin J Scherlag, Youqi Fan, John W Dyer, Shailesh Male, Vandana Varma, Yong Sha, Stavros Stavrakis
    Abstract:

    Background We studied the effects of transcutaneous electrical stimulation at the Tragus, the anterior protuberance of the outer ear, for inhibiting atrial fibrillation (AF). Objective To develop a noninvasive transcutaneous approach to deliver low-level vagal nerve stimulation to the Tragus in order to treat cardiac arrhythmias such as AF. Methods In 16 pentobarbital anesthetized dogs, multielectrode catheters were attached to pulmonary veins and atria. Three tungsten-coated microelectrodes were inserted into the anterior right ganglionated plexi to record neural activity. Tragus stimulation (20 Hz) in the right ear was accomplished by attaching 2 alligator clips onto the Tragus. The voltage slowing the sinus rate or atrioventricular conduction was used as the threshold for setting the low-level Tragus stimulation (LL-TS) at 80% below the threshold. At baseline, programmed stimulation determined the effective refractory period (ERP) and the window of vulnerability (WOV), a measure of AF inducibility. For hours 1–3, rapid atrial pacing (RAP) was applied alone, followed by concomitant RAP+LL-TS for hours 4–6 (N = 6). The same parameters were measured during sinus rhythm when RAP stopped after each hour. In 4 other animals, bivagal transection was performed before LL-TS. Results During hours 1–3 of RAP, there was a progressive and significant decrease in ERP, increase in WOV, and increase in neural activity vs baseline (all P P Conclusions LL-TS can reverse RAP-induced atrial remodeling and inhibit AF inducibility, suggesting a potential noninvasive treatment of AF.

Km Mahadi - One of the best experts on this subject based on the ideXlab platform.

  • cardiovascular autonomic effects of transcutaneous auricular nerve stimulation via the Tragus in the rat involve spinal cervical sensory afferent pathways
    Brain Stimulation, 2019
    Co-Authors: Km Mahadi, Sa Deuchars, Varinder K Lall, Jim Deuchars
    Abstract:

    Abstract Background Electrical stimulation on select areas of the external auricular dermatome influences the autonomic nervous system. It has been postulated that activation of the Auricular Branch of the Vagus Nerve (ABVN) mediates such autonomic changes. However, the underlying neural pathways mediating these effects are unknown and, further, our understanding of the anatomical distribution of the ABVN in the auricle has now been questioned. Objective To investigate the effects of electrical stimulation of the Tragus on autonomic outputs in the rat and probe the underlying neural pathways. Methods Central neuronal projections from nerves innervating the external auricle were investigated by injections of the transganglionic tracer cholera toxin B chain (CTB) into the right Tragus of Wistar rats. Physiological recordings of heart rate, perfusion pressure, respiratory rate and sympathetic nerve activity were made in an anaesthetic free Working Heart Brainstem Preparation (WHBP) of the rat and changes in response to electrical stimulation of the Tragus analysed. Results Neuronal tracing from the Tragus revealed that the densest CTB labelling was within laminae III-IV of the dorsal horn of the upper cervical spinal cord, ipsilateral to the injection sites. In the medulla oblongata, CTB labelled afferents were observed in the paratrigeminal nucleus, spinal trigeminal tract and cuneate nucleus. Surprisingly, only sparse labelling was observed in the vagal afferent termination site, the nucleus tractus solitarius. Recordings made from rats at night time revealed more robust sympathetic activity in comparison to day time rats, thus subsequent experiments were conducted in rats at night time. Electrical stimulation was delivered across the Tragus for 5 min. Direct recording from the sympathetic chain revealed a central sympathoinhibition by up to 36% following Tragus stimulation. Sympathoinhibition remained following sectioning of the cervical vagus nerve ipsilateral to the stimulation site, but was attenuated by sectioning of the upper cervical afferent nerve roots. Conclusions Inhibition of the sympathetic nervous system activity upon electrical stimulation of the Tragus in the rat is mediated at least in part through sensory afferent projections to the upper cervical spinal cord. This challenges the notion that tragal stimulation is mediated by the auricular branch of the vagus nerve and suggests that alternative mechanisms may be involved.

  • Cardiovascular autonomic effects of transcutaneous auricular nerve stimulation via the Tragus in the rat involve spinal cervical sensory afferent pathways.
    'Elsevier BV', 2019
    Co-Authors: Km Mahadi, Vk Lall, Sa Deuchars, Deuchars J
    Abstract:

    Background Electrical stimulation on select areas of the external auricular dermatome influences the autonomic nervous system. It has been postulated that activation of the Auricular Branch of the Vagus Nerve (ABVN) mediates such autonomic changes. However, the underlying neural pathways mediating these effects are unknown and, further, our understanding of the anatomical distribution of the ABVN in the auricle has now been questioned. Objective To investigate the effects of electrical stimulation of the Tragus on autonomic outputs in the rat and probe the underlying neural pathways. Methods Central neuronal projections from nerves innervating the external auricle were investigated by injections of the transganglionic tracer cholera toxin B chain (CTB) into the right Tragus of Wistar rats (n=4). Physiological recordings of heart rate, perfusion pressure, respiratory rate and sympathetic nerve activity were made in an anaesthetic free Working Heart Brainstem Preparation (WHBP) of the rat and changes in response to electrical stimulation of the Tragus analysed. Results Neuronal tracing from the Tragus revealed that the densest CTB labelling was within laminae III-IV of the dorsal horn of the upper cervical spinal cord, ipsilateral to the injection sites. In the medulla oblongata, CTB labelled afferents were observed in the paratrigeminal nucleus, spinal trigeminal tract and cuneate nucleus. Surprisingly, only sparse labelling was observed in the vagal afferent termination site, the nucleus tractus solitarius. Recordings made from rats at night time revealed more robust sympathetic activity in comparison to day time rats, thus subsequent experiments were conducted in rats at night time. Electrical stimulation was delivered across the Tragus for 5 minutes. Direct recording from the sympathetic chain revealed a central sympathoinhibition by up to 36% following Tragus stimulation. Sympathoinhibition remained following sectioning of the cervical vagus nerve ipsilateral to the stimulation site, but was attenuated by sectioning of the upper cervical afferent nerve roots. Conclusions Inhibition of the sympathetic nervous system activity upon electrical stimulation of the Tragus in the rat is mediated at least in part through sensory afferent projections to the upper cervical spinal cord. This challenges the notion that tragal stimulation is mediated by the auricular branch of the vagus nerve and suggests that alternative mechanisms may be involved

Sa Deuchars - One of the best experts on this subject based on the ideXlab platform.

  • cardiovascular autonomic effects of transcutaneous auricular nerve stimulation via the Tragus in the rat involve spinal cervical sensory afferent pathways
    Brain Stimulation, 2019
    Co-Authors: Km Mahadi, Sa Deuchars, Varinder K Lall, Jim Deuchars
    Abstract:

    Abstract Background Electrical stimulation on select areas of the external auricular dermatome influences the autonomic nervous system. It has been postulated that activation of the Auricular Branch of the Vagus Nerve (ABVN) mediates such autonomic changes. However, the underlying neural pathways mediating these effects are unknown and, further, our understanding of the anatomical distribution of the ABVN in the auricle has now been questioned. Objective To investigate the effects of electrical stimulation of the Tragus on autonomic outputs in the rat and probe the underlying neural pathways. Methods Central neuronal projections from nerves innervating the external auricle were investigated by injections of the transganglionic tracer cholera toxin B chain (CTB) into the right Tragus of Wistar rats. Physiological recordings of heart rate, perfusion pressure, respiratory rate and sympathetic nerve activity were made in an anaesthetic free Working Heart Brainstem Preparation (WHBP) of the rat and changes in response to electrical stimulation of the Tragus analysed. Results Neuronal tracing from the Tragus revealed that the densest CTB labelling was within laminae III-IV of the dorsal horn of the upper cervical spinal cord, ipsilateral to the injection sites. In the medulla oblongata, CTB labelled afferents were observed in the paratrigeminal nucleus, spinal trigeminal tract and cuneate nucleus. Surprisingly, only sparse labelling was observed in the vagal afferent termination site, the nucleus tractus solitarius. Recordings made from rats at night time revealed more robust sympathetic activity in comparison to day time rats, thus subsequent experiments were conducted in rats at night time. Electrical stimulation was delivered across the Tragus for 5 min. Direct recording from the sympathetic chain revealed a central sympathoinhibition by up to 36% following Tragus stimulation. Sympathoinhibition remained following sectioning of the cervical vagus nerve ipsilateral to the stimulation site, but was attenuated by sectioning of the upper cervical afferent nerve roots. Conclusions Inhibition of the sympathetic nervous system activity upon electrical stimulation of the Tragus in the rat is mediated at least in part through sensory afferent projections to the upper cervical spinal cord. This challenges the notion that tragal stimulation is mediated by the auricular branch of the vagus nerve and suggests that alternative mechanisms may be involved.

  • Cardiovascular autonomic effects of transcutaneous auricular nerve stimulation via the Tragus in the rat involve spinal cervical sensory afferent pathways.
    'Elsevier BV', 2019
    Co-Authors: Km Mahadi, Vk Lall, Sa Deuchars, Deuchars J
    Abstract:

    Background Electrical stimulation on select areas of the external auricular dermatome influences the autonomic nervous system. It has been postulated that activation of the Auricular Branch of the Vagus Nerve (ABVN) mediates such autonomic changes. However, the underlying neural pathways mediating these effects are unknown and, further, our understanding of the anatomical distribution of the ABVN in the auricle has now been questioned. Objective To investigate the effects of electrical stimulation of the Tragus on autonomic outputs in the rat and probe the underlying neural pathways. Methods Central neuronal projections from nerves innervating the external auricle were investigated by injections of the transganglionic tracer cholera toxin B chain (CTB) into the right Tragus of Wistar rats (n=4). Physiological recordings of heart rate, perfusion pressure, respiratory rate and sympathetic nerve activity were made in an anaesthetic free Working Heart Brainstem Preparation (WHBP) of the rat and changes in response to electrical stimulation of the Tragus analysed. Results Neuronal tracing from the Tragus revealed that the densest CTB labelling was within laminae III-IV of the dorsal horn of the upper cervical spinal cord, ipsilateral to the injection sites. In the medulla oblongata, CTB labelled afferents were observed in the paratrigeminal nucleus, spinal trigeminal tract and cuneate nucleus. Surprisingly, only sparse labelling was observed in the vagal afferent termination site, the nucleus tractus solitarius. Recordings made from rats at night time revealed more robust sympathetic activity in comparison to day time rats, thus subsequent experiments were conducted in rats at night time. Electrical stimulation was delivered across the Tragus for 5 minutes. Direct recording from the sympathetic chain revealed a central sympathoinhibition by up to 36% following Tragus stimulation. Sympathoinhibition remained following sectioning of the cervical vagus nerve ipsilateral to the stimulation site, but was attenuated by sectioning of the upper cervical afferent nerve roots. Conclusions Inhibition of the sympathetic nervous system activity upon electrical stimulation of the Tragus in the rat is mediated at least in part through sensory afferent projections to the upper cervical spinal cord. This challenges the notion that tragal stimulation is mediated by the auricular branch of the vagus nerve and suggests that alternative mechanisms may be involved

Mark S George - One of the best experts on this subject based on the ideXlab platform.

  • neurophysiologic effects of transcutaneous auricular vagus nerve stimulation tavns via electrical stimulation of the Tragus a concurrent tavns fmri study and review
    Brain Stimulation, 2017
    Co-Authors: Bashar W Badran, Logan T Dowdle, Oliver Mithoefer, Nicholas T Labate, James Coatsworth, Joshua C Brown, William H Devries, Christopher W Austelle, Lisa M Mcteague, Mark S George
    Abstract:

    Abstract Background Electrical stimulation of the auricular branch of the vagus nerve (ABVN) via transcutaneous auricular vagus nerve stimulation (taVNS) may influence afferent vagal networks. There have been 5 prior taVNS/fMRI studies, with inconsistent findings due to variability in stimulation targets and parameters. Objective We developed a taVNS/fMRI system to enable concurrent electrical stimulation and fMRI acquisition to compare the effects of taVNS in relation to control stimulation. Methods We enrolled 17 healthy adults in this single-blind, crossover taVNS/fMRI trial. Based on parameters shown to affect heart rate in healthy volunteers, participants received either left Tragus (active) or earlobe (control) stimulation at 500 μs 25 HZ for 60 s (repeated 3 times over 6 min). Whole brain fMRI analysis was performed exploring the effect of: active stimulation, control stimulation, and the comparison. Region of interest analysis of the midbrain and brainstem was also conducted. Results Active stimulation produced significant increased BOLD signal in the contralateral postcentral gyrus, bilateral insula, frontal cortex, right operculum, and left cerebellum. Control stimulation produced BOLD signal activation in the contralateral postcentral gyrus. In the active vs. control contrast, Tragus stimulation produced significantly greater BOLD increases in the right caudate, bilateral anterior cingulate, cerebellum, left prefrontal cortex, and mid-cingulate. Conclusion Stimulation of the Tragus activates the cerebral afferents of the vagal pathway and combined with our review of the literature suggest that taVNS is a promising form of VNS. Future taVNS/fMRI studies should systematically explore various parameters and alternative stimulation targets aimed to optimize this novel form of neuromodulation.