Mapping functional connectivity and structural covariance of the striatum: applications to Obsessive-Compulsive Disorder research (abstract)

Functional and structural abnormalities of the neostriatum have been typically described in Obsessive-Compulsive Disorder (OCD). These alterations were supposed to affect network activity within the different cortico-striatal circuits linking the striatum with the frontal cortex, which are involved in the regulation of specific motor, cognitive and affective functions. Nevertheless, it has not been till recently that these putative network alterations were confirmed by means of functional connectivity assessments. Specifically, an increased functional connectivity between the ventral striatum and the orbitofrontal cortex was described in combination with a decreased functional connectivity between the dorsal striatum and dorso-lateral prefrontal regions. In addition, these functional connectivity alterations seem to show some degree of specificity across OCD clinical subtypes. Interestingly, when assessing the structural covariance (i.e., the volumetric correlations across distant structures) of these same striatal territories, we observed patterns of covariance resembling those described at the functional connectivity level, suggesting that the existence of functional connectivity is one of the factors leading to the development of structural covariance. Not surprisingly, structural covariance patterns within fronto-striatal loops are also altered in OCD patients. These results allow the characterization of OCD as a system-level disorder.