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ipsilateral visual stimulation, and MT was identified as the caudally adjacent area on the
cortical surface that did not respond to ipsilateral visual stimulation.
Somatosensory brain regions were identified with a rapid event-related fMRI
experiment in which the palms and soles of the left and right hands and feet were
stimulated with brief Vibrotactile pulses (Burton, et al. 2004). As shown in Figure IB,
vibro-tactile stimulation evoked a vigorous response concentrated in the parietal
operculum, the location Ofsecondary somatosensory cortex and other somatosensory
association areas (S2+).
Vibrotactile responses were also observed in "visual" regions of lateral
occipitotemporal cortex. To determine the spatial relationship between tactile
responses and the location of identified visual areas, composite activation maps were
created for an individual subject (Fig. 1C) and for the group activation map (Fig. 1D,E).
Tactile responses were consistently observed in MST but not in MT. To quantify
the relative areas of tactile activation in MT and MST, we counted the number of
suprathreshold nodes in the group average cortical surface model. In the left
hemisphere, 2% of MT nodes and 49% of MST nodes showed significant tactile
activation, whereas in the right hemisphere, 7% of nodes in MT and 43% of nodes in
MsTweresignificantIyactive.