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Abstract:
We are interested in the pathways supporting tactile motion
perception and their potential overlap and interaction with visual
motion pathways. As the first in a series of studies using fMRI at
3T, we localized activation evoked by moving visual concentric
rings in subjects that had also received event-related vibrotactile
stimulation of the 3rd digit fingertip (Moore et al., this volume).
We found overlapping tactile and visual activation in the right
posterior insula/temporoparietal junction, a region that may
correspond to the retro-insular area in macaques. Robust activation
was evoked by moving visual stimuli but was not observed following
the transition from visual fixation to the presentation of red or
green shapes. Responses in this area were also robust to 20- or
100-Hz 1s-duration vibrotactile stimuli, and were generally scaled
to the amplitude of tactile input. As in the posterior-PoCG, this
region had longer-latency responses correlated with ipsilateral
motor activity. However, the hemodynamic waveform evoked during
tactile stimulation without motor response resembled more closely
the transient activation observed in the anterior-PoCG, as compared
to more sustained activation of the posterior-PoCG. In general,
activation evoked by tactile stimulation in other temporal and
parietal regions was inter-digitated with, but not overlapping,
activation evoked by visual motion stimuli.
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