OBSESSIVE-COMPULSIVE DISORDER AND THE BASAL GANGLIA

Obsessive-compulsive disorder (OCD), characterized by obsessions and compulsions, was described as more frequent in patients with primary lesions of the basal ganglia suggesting that these brain structures may be also altered in OCD. The basal ganglia, that were considered important only for the motor control, are known now as crucial for many other mental functions as processing of cognitive experience. Recent Studies using magnetic resonance image have found a tendency for smaller caudate nucleus in patients with OCD. Consistently, studies using functional neuroimaging suggest implication of a neurocircuit that includes the orbitalfrontal cortex, the cingulate cortex, caudate nucleus and thalamus in the pathophysiology of OCD. Among several hypotheses formulated to explain these findings, some authors speculated that a deficit of the caudate nucleus function would lead to inadequate filtering of worry inputs which would trigger the orbitalfrontal cortex to develop adaptative responses: the compulsions.