[Challenge to understand the neurobiology of obsessive-compulsive disorder]

Obsessive-compulsive disorder (OCD) is characterized by obsession (recurrent intrusive thoughts) and compulsion (repetitive behaviors or mental acts). There is no consensus regarding the pathogenesis of OCD, which could support the idea that this disorder is heterogeneous. However, functional imaging data and surgical findings in humans suggest that the hyperactivity of the specific circuit including the striatum, called the cortico-striato-thalamo-cortical circuit, plays a role in OCD pathogenesis. Recently, validated animal models of OCD have been established, and they provide us the opportunity to address how the altered functional activity of this circuit contributes to the repetitive behavior in OCD. To test the causal relationship between the altered function of the circuit and behavioral abnormalities in animals, cell-type-specific manipulation and detection of changes in the circuit will be required. Optogenetic approaches may be used as tools to dissect the complex circuit. Moreover, mouse functional magnetic resonance imaging may yield data comparable to human imaging data.