The brain areas activated by bilateral galvanic vestibular stimulation
(GVS) were studied using functional magnetic resonance imaging.
In six human volunteers, GVS led to activation in the region
of the temporoparietal junction, the central sulcus, and the
anterior interior intraparietal sulcus, which may correspond
to macaque areas PIVC, 3aV, and 2v, respectively. In addition,
activation was found in premotor regions of the frontal lobe,
presumably analogous to areas 6pa and 8a in the monkey. Since
these areas were not detected in previous studies using caloric
vestibular stimulation, they could be related to the modulation
of otolith afferent activity by GVS. However, the simple paradigm
used did not allow separation of the otolithic and semicircular
canal effects of GVS. Further studies must be performed to clarify
the question of cortical representation of the otolithic information
in the human and monkey brain.
