CEREBRAL FUNCTIONAL MAGNETIC-RESONANCE-IMAGING OF VESTIBULAR, AUDITORY, AND NOCICEPTIVE AREAS DURING GALVANIC STIMULATION

Cerebral activation was investigated with functional magnetic resonanc e imaging (fMRI) during galvanic stimulation of the mastoid in 6 norma l 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, PI VC), the transverse temporal (Heschl's) gyrus, and thalamic pulvinar. The cutaneous pain elicited by galvanic stimulation caused bilateral a ctivity of the medial part of the insula and the anterior median thala mus. Thus, galvanic stimulation at the mastoid level activates cortica l areas of three different sensory systems in the insulathalamic regio n, the vestibular, the auditory, and the nociceptive systems.