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Abstract:
Results from many lines of research point towards
dysfunctions in the fronto-striatal circuits as a neurobiological
substrate of Obsessive-Compulsive Disorder (OCD). However, the
relative contribution of different components of these circuits in
generating the OCD symptoms is still unclear. Based on results that
suggest an evaluative role for the Anterior Cingulate Cortex (ACC)
and evidence of hyperactivity of the ACC in OCD, we hypothesized
that OCD patients might be characterized by an overactive
evaluative function of the ACC. We tested this hypothesis using
event-related fMRI to compare the ACC activation in a group of OCD
patients with that of a group of matched healthy subjects, in
response to a modified version of a continuous performance task
which manipulated the level of response conflict. Behaviorally, the
patients' accuracy was similar to that of controls. ACC activation
in response to high conflict trials was higher in the patient
group, as was the error-related activity in the same region of the
ACC. These findings suggest that an impairment in the evaluative
function of the ACC plays a significant role in the pathogenesis of
OCD.
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