NEUROIMAGING AND FRONTAL-SUBCORTICAL CIRCUITRY IN OBSESSIVE-COMPULSIVE DISORDER

Background Neuroimaging studies provide strong evidence that the patho physiology of obsessive - compulsive disorder (OCD) involves abnormal functioning along specific frontal-subcortical brain circuits. Method A literature search was carried out for all brain imaging studies of p atients with OCD. We also reviewed the basic science literature on the functional neuroanatomy of cortico-basal ganglia circuits, and integr ated this information with neuroimaging data in OCD to formulate a the oretical model of brain mediation of OCD symptoms and response to trea tment. Results At least a subgroup of patients with OCD may have abnor mal basal ganglia development. Functional neuroimaging studies indicat e that OCD symptoms are associated with increased activity in orbitofr ontal cortex, caudate nucleus, thalamus and anterior cingulate gyrus. Conclusions OCD symptoms are mediated by hyperactivity in orbitofronta l-subcortical circuits, perhaps due to an imbalance of tone between di rect and indirect striato-pallidal pathways. We present a model which describes how frontal-subcortical brain circuitry may mediate OCD symp tomatology, and suggest a hypothesis for how successful treatments may ameliorate symptoms, via their effects on circuit activity.