A transient decrease in heart rate with unilateral and bilateral galvanic vestibular stimulation in healthy humans

Abstract

The study of cardiovascular function with galvanic vestibular stimulation has provided evidence on the neural structures that are involved in the vestibulo-autonomic reflex. This study determined if the effect on heart rate using galvanic vestibular stimulation persists after provoking a sympathetic response and if this response differs when using unilateral or transmastoid (bilateral) stimulation. We analysed heart rate and heart rate variability using unilateral and transmastoid galvanic vestibular stimulation combined with cardiovascular reflex evoked by postural change in 24 healthy human subjects. Three electrode configurations were selected for unilateral stimulation considering the anatomical location of each semicircular canal. We compared recordings performed in seated and standing positions, and with unilateral and transmastoid stimulation. With subjects seated, a significant transient decrease in heart rate was observed with unilateral stimulation. With transmastoid stimulation, heart rate decreased in both seated and standing positions. Average intervals between normal heartbeats recorded with stimulation resemble parasympathetic cardiac function induced by auricular vagal nerve stimulation. Our results indicate that unilateral stimulation does not eliminate the natural heart rate increase caused by orthostatic hypotension. In contrast, transmastoid stimulation provoked a transient reduction in heart rate, even when subjects were standing. These responses should be considered while performing experiments with galvanic vestibular stimulation and subsequent effects in cardiac regulation mechanisms.

The role of otolith reflexes in orthostatic intolerance

“…Kim and colleagues [10] excluded patients with identified peripheral and central vestibular disorders, limiting the application of these findings to those without obvious Fig. 1 Vestibular-autonomic reflexes are involved in pathways associated with sympathetic and parasympathetic outflows [2,3]. Descending pathways lead to the ventrolateral medulla, influencing the vestibulo-sympathetic reflexes, vestibulo-respiratory reflexes and nausea/vomiting centers.…”

“…The vestibulo-autonomic system describes various pathways through the brainstem, vestibulocerebellum, and insular cortex associated with altered sympathetic and parasympathetic responses (Fig. 1) [1][2][3]. Vestibulo-autonomic reflexes have been described for decades, specifically in the context of cardiovascular and respiratory function, as well as in motion sickness [4].…”

Vestibular-autonomic interactions: beyond orthostatic dizziness

“…The vestibular-autonomic reflexes encompass numerous pathways triggered by vestibular activation, resulting in changes in sympathetic or parasympathetic outflows [4,5 vestibular nucleus to the parabrachial complex [6], which sends projections to brainstem and forebrain areas integrating vestibular sensation and autonomic control, and cerebellar modulation of brainstem areas mediating autonomic output [1,[7][8][9][10][11][12][13]. Various sites within the cerebellum (anterior lobe, rostral posterior lobe, caudal posterior lobe-nodulus) demonstrate the ability to influence sympathetic and parasympathetic reflexes [14][15][16]17 && ].…”

“…The vestibular-autonomic reflexes encompass numerous pathways triggered by vestibular activation, resulting in changes in sympathetic or parasympathetic outflows [4,5 ▪▪ ]. Primary pathways include a descending tract from the inferior vestibular nucleus to the dorsal motor nucleus of the vagus and the ventrolateral medulla, an ascending pathway from the rostral vestibular nucleus to the parabrachial complex [6], which sends projections to brainstem and forebrain areas integrating vestibular sensation and autonomic control, and cerebellar modulation of brainstem areas mediating autonomic output [1,7–13].…”

Cobertura De Pilha De Estéril Em Climas Semi-Áridos

“…These studies acquired physiological signals invasively in anesthetized animals (COHEN, 2011). In human subjects, a HR decrease, and HR variability increase was observed with GVS, even after a postural shift from sitting to standing, without a clear result on BP changes (PLIEGO, 2021). For these, it is necessary to use a BP measurement method, sensitive to beat-to-beat cardiovascular changes, able to be used in experiments that involve movement tasks in combination with electrical vestibular stimulation.…”