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Abstract:
Studies have implicated frontal and parietal cortical brain
regions in the general performance of antisaccade tasks.
Antisaccade task performance relies on one's ability to suppress a
reflexive, sensory guided saccade made toward a cue in favor of a
volitional saccade made away from a cue. However, this inhibitory
process is brief in duration compared to other task demands such as
prolonged fixation and the generation of saccades. To date,
neuroimaging studies have only employed blocked designs which lack
the requisite temporal resolution to identify brain regions
specifically related to inhibition of reflexive saccades. With this
issue in mind, the current study used an interleaved antisaccade
paradigm optimized for event-related functional magnetic resonance
imaging (fMRI). At the beginning of a trial, subjects were given an
instruction that called for a prosaccade, antisaccade, or
no-saccade on the occurrence of a suddenly appearing peripheral
cue. Simultaneous monitoring of eye movements in the scanner
allowed us to relate fMRI data with performance accuracy.
Event-related fMRI methods were used to identify neural regions
active during instruction, prestimulus preparation, and response
phases. Preliminary analyses suggest that although the frontal,
supplementary, and parietal eye fields were active at the time of
response, the supplementary eye fields showed greater activity
prior to the cue on trials in which a reflexive saccade was
withheld. These data help clarify the different roles (e.g., motor,
control, and perceptual) for the frontal, supplementary, and
parietal eye fields during performance of the antisaccade
task.
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