Cerebral functional magnetic resonance imaging of vestibular, auditory, and nociceptive areas during galvanic stimulation

Abstract

Cerebral activation was investigated with functional magnetic resonance imaging (fMRI) during galvanic stimulation of the mastoid in 6 normal volunteers. Cutaneous stimulation at the neck C4-5 level served as a control. During mastoid stimulation, bilateral vestibular activation occurred in the posterior insula (parietoinsular vestibular cortex, PIVC), the transverse temporal (Heschl's) gyrus, and thalamic pulvinar. The cutaneous pain elicited by galvanic stimulation caused bilateral activity of the medial part of the insula and the anterior median thalamus. Thus, galvanic stimulation at the mastoid level activates cortical areas of three different sensory systems in the insulathalamic region, the vestibular, the auditory, and the nociceptive systems.

The thalamocortical vestibular system in animals and humans

“…The activation of these two latter thalamic nuclei in humans is compatible with the implication of the ventroposterior complex of the monkey (VPL, VPI, VPM, VPP) in vestibular processing (Büttner and Henn, 1976;Deecke et al, 1974Deecke et al, , 1977Lang et al, 1979;Marlinski and McCrea, 2008a). Bucher et al (1998) reported that galvanic vestibular stimulation evoked a bilateral activation of two thalamic regions: one located in the posterior median thalamus, and a second located in the anterior paramedian thalamus (that was also activated during a control nociceptive stimulation). These authors argued that the thalamic nuclei involved in vestibular processing were the nucleus medialis, nucleus habenularis and the pulvinar.…”

“…No neuroimaging study using such methods has so far specifically focused on thalamic activations during vestibular stimulation. However, several neuroimaging studies describing the location of the vestibular cortex in healthy participants have also revealed thalamic activations during caloric (Bottini et al, 2001;Deutschländer et al, 2002;Dieterich et al, 2003;Marcelli et al, 2009;Suzuki et al, 2001) and galvanic (Bense et al, 2001;Bucher et al, 1998;Stephan et al, 2005) stimulation of the peripheral vestibular receptors. In a study using galvanic vestibular stimulation, Bense et al (2001) reported an activation of the paramedian and dorsolateral thalamus, whereas in a study using caloric vestibular stimulation, Dieterich et al (2003) reported an activation of the posterolateral and posteromedial thalamus.…”

“…Functional neuroimaging studies performed in healthy subjects during caloric and galvanic vestibular stimulation have unanimously demonstrated activation of the posterior insula and temporo-parietal junction (TPJ), that could represent the human homologue of the monkey PIVC (Bense et al, 2001;Bottini et al, 1994Bottini et al, , 1995Bottini et al, , 2001Bucher et al, 1998;Dieterich et al, 2003;Eickhoff et al, 2006b;Emri et al, 2003;Fasold et al, 2002;Fink et al, 2003;Friberg et al, 1985;Hegemann et al, 2003;Indovina et al, 2005;Lobel et al, 1998;Marcelli et al, 2009;Miyamoto et al, 2007;Naito et al, 2003;Petit and Beauchamp, 2003;Schlindwein et al, 2008;Stephan et al, 2005;Suzuki et al, 2001;Tuohimaa et al, 1983;Vitte et al, 1996). These activations centered on the superior temporal gyrus, the posterior and anterior insula, or the inferior parietal lobule (Fig.…”

Body ownership and embodiment: Vestibular and multisensory mechanisms

“…Accordingly, we propose that this spatial dissociation between self and body location (that is very prominent in out-of-body experiences) might reflect partial disembodiment as it can be observed in patients with autoscopic phenomena in whom vestibular illusions are often associated symptoms [14,17,83] and in healthy subjects using multisensory conflict and virtual reality [84]. This observation is supported by the activation of the vestibular cortex by galvanic vestibular stimulations [6,32,37,46,51,85,110] overlapping with key structures of embodiment such as the TPJ and the temporooccipital cortex [5,16].…”

“…Congruently, epileptic patients with vestibular aurae suffer from lesions surrounding the superior temporal gyrus and the temporoparietal cortex [99,107]. This location has also been confirmed by functional neuroimaging studies in healthy subjects using caloric and galvanic stimulation of the peripheral vestibular system revealing unanimously predominant activations centered on the TPJ and insula [6,19,20,32,39,46,47,50,51,70,72,85,94,95,110,112,118] with activations in the superior temporal gyrus, posterior insula, inferior parietal lobule (angular and supramarginal gyri), and postcentral gyrus. Although many regions surrounding the TPJ/insula have been found activated, opinions concerning the exact location of the human homologue of the PIVC differ (Fig.…”