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Voxels were classified as being somatosensory responsive if any combination of
left and right hand or foot regressors showed a significant (p<0.01) effect. Group
average Somatosensorytime series were created by calculating the average time series
in each individual hemisphere, reordering the time series so that right (contralateral)
hand and foot responses in left hemisphere were averaged with left (contralateral)
responses in right hemisphere, and ipsilateral responses in left hemisphere were
averaged with ipsilateral responses in right hemisphere, averaging across hemispheres
to create individual subject time series, and then collapsing into a grand mean. In each
individual, the MST time series was created from only those voxels that showed a
significant Vibrotactile response. In many hemispheres, there were no voxels in MT with
significant Vibrotactile responses, so the time series was created from all voxels in the
MTROI.
Behavioraltask
To ensure that subjects remained alert and attentive throughout the
experiment, we used a catch trial design adapted from magnetoencephalography
experimental designs. Infrequently (10 trials per 5 min scan series), the piezoelectric
bender affixed to the subject's hip (the catch stimulus) would be activated. This signaled
the subject to make an eye movement to a visual target (white fixation crosshairs)
placed in the upper right corner of the display screen, which was otherwise blank except
for the target. BOLD data from catch trials and any false alarm trials were analyzed
separately from all other trials, so that oculomotor and visual brain activations produced