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Abstract:
Recent examination of the anterior cingulate (ACC) and the
dorsolateral prefrontal cortices (DLPFC) revealed dissociable
functions for these two regions. ACC function has been implicated
in detecting response conflict, while the DLPFC demonstrates
differential activity to degree of top-down control. The present
study investigated the interplay between these two regions using a
cued set-switching task. Eight subjects performed the task during
fMRI on a 3.0-T G.E. scanner. Increased ACC activity in response to
high conflict trials and more DLPFC activity to trials that require
more control, as well as a tradeoff in the level of activity in
these two regions were anticipated. Single subject fMRI results
confirmed higher DLPFC activity when subjects prepared for
nonprepotent trials. As predicted, ACC activity was higher to error
trials and to nonprepotent trials. Further, increased activity was
found in the ACC during nonprepotent trials in subjects whose DLPFC
activity was low during the interval following the cue. Greater ACC
activity in this condition may be accounted for by the increased
conflict engendered when there is less DLPFC related recruitment of
control processes. Event-related potentials will be recorded while
the same subjects perform this task to further examine the
relationship between the DLPFC and ACC during cognitive
control.
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