Changes in brain activation caused by caloric stimulation in the case of cochleovestibular denervation - PET study

Abstract

There are a number of well-known stimulation methods for the investigation of the central projection of the vestibular system. In addition to optokinetic, galvanic and neck vibration tests, the most widespread method is caloric stimulation. These listed methods cause not only vestibular, but also other effects on the central nervous system (CNS) (acoustic, tactile and nociceptive). In this paper, positron emission tomography (PET) was used to investigate whether caloric stimulation contains a non-vestibular (extravestibular) component, which would cause a distortion in the cortical activity and therefore in the vestibular effect on the CNS. Caloric stimulation was carried out in six patients who had been operated on due to cerebello-pontine angle tumour. These patients suffered post-operatively from a complete lesion of the vestibular system and anacusis on the operated side. Ipsilaterally activated areas were the inferior pole of the post-central gyrus and temporoparietal junction, caudal part of the post-central gyrus (SI, SII), inferior parietal lobule and medial frontal gyrus. Contralaterally activated areas were the anterior cingulate gyrus, medial frontal gyrus, posterior part of the insula, post-central gyrus and temporoparietal junction (SII). Ipsilaterally deactivated areas were the caudal and cranial part of the medial occipital gyrus (V2, V3, V4, V5). Contralaterally deactivated areas were the lingual gyrus, inferior occipital gyrus (V2, V3) and fusiform gyrus. On the basis of these data, it was postulated that, during caloric stimulation, extravestibular reaction also occurs, which corresponds to the subjective feeling of heat and pain. The deactivation of the occipital cortex due to an extravestibular effect was demonstrated. This is the first observation to suggest the possibility of nociceptivevisual interaction.

High-resolution fMRI detects neuromodulation of individual brainstem nuclei by electrical tongue stimulation in balance-impaired individuals

“…For example, Danckert and colleagues found increased activation of the ACC when healthy subjects were asked to point while wearing prism glasses, leading to errors between their visual and motor systems (Danckert, Ferber, Goodale 2008). Several other imaging studies using direct vestibular stimulation (caloric and galvanic) and visual stimulation have shown activations of the ACC (Calhoun et al, 2001; Kisely et al, 2002; Miyamoto et al, 2007). We believe the decreased activation of this region after CN-NINM represents the decreased ability of motion in the visual field to induce the sensation of ego-motion and therefore a reduction in the error signal processed by the ACC.…”

Studies of caloric vestibular stimulation: implications for the cognitive neurosciences, the clinical neurosciences and neurophilosophy

“…As with many phenomena targeted by brain‐imaging studies, the CVS imaging studies are complex however consistent findings of contralateral hemispheric activation have been shown. These activated regions include anterior cingulate cortex (ACC), temporoparietal cortex and insular cortex [detailed below (7–15)]. Such regions have been linked by brain‐imaging, lesion and other studies to the various phenomena affected by CVS.…”

Cortical Activity During an Attack of Ménière's Disease—A Case Report

“…It is noteworthy that there is decreased activity in these areas during the attack compared to the patient's own baseline brain activity. Previous studies have also shown increased activity in these areas during artificial vestibular stimulation as caloric, sound or galvanic stimulation (16)(17)(18).…”