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Abstract:
Visual tracking allows us to maintain a moving target of
interest on the fovea. The first aim of our study was to determine
whether any cortical areas were more activated during visual
tracking than during saccadic eye movements, which shift attention
to stationary targets. fMRI images were acquired at 3 Tesla from
healthy adult subjects (N=6) performing visual tracking and saccade
tasks in alternation. We identified a region in human posterior
cingulate cortex that was more active during visual tracking than
during saccades. To determine whether the visual tracking
activation during was due to motion perception, we acquired images
from the same subjects while they passively viewed a motion
stimulus alternating with a stationary stimulus. This comparison
yielded only weak activation in posterior cingulate, suggesting
that passive motion perception is not sufficient to drive the
activation observed during visual tracking. To determine whether
the visual tracking activation depended on specific task
parameters, we acquired images from a second set of subjects
performing the tasks at a different saccade rate and visual
tracking velocity. Activation in posterior cingulate remained
significantly greater for visual tracking than for saccades. These
experiments show that a region in posterior cingulate cortex is
preferentially activated during tracking of a continuously moving
visual target.
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