Involvement of the thalamic-cortical-striatal circuit in patients with obsessive-compulsive disorder during an inhibitory control task with reward and punishment contingencies

Recent neuroimaging studies conducted on obsessive-compulsive disorder (OCD) show alterations in the fronto-thalamic-striatal circuit, which would give rise to an executive dysfunction. This could be the neurocognitive substrate underlying the main symptoms of OCD, i.e. obsessions and compulsions. Both brain activity and behavioural performance of a group of 13 patients with OCD were compared with a control group of 13 healthy subjects by means of functional magnetic resonance imaging while performing an inhibitory control task with reward and punishment contingencies. The effects of medication were also analysed. The intra-group analyses showed a longer reaction time during the go/no go condition in both groups, although there were no differences between the groups in the performance of the task. With regard to this task, significant activation of large areas of the cerebellum and the occipital, temporal and parietal lobes was observed in the healthy subjects. In comparison with the controls, the obsessive patients showed lower activation in the right-side frontal medial and superior gyri, the anterior cingulate cortex and the caudate nucleus, and greater activation in the inferior parietal convolution and the fusiform gyrus. The effects of medication were found in the frontal cortex and basal structures. These results agree with the argument claiming that the dysfunction in the corticostriatal system in OCD is associated to diminished brain activity in response to cognitive tasks.