Grant: Master's Award: Canada Graduate Scholarships

Obsessive-compulsive disorder (OCD) is a heritable mental disorder characterized by intrusive thoughts, impulses, or repetitive behaviours. In addition to the anxiety and emotional distress experienced by those with OCD, sufferers also present with impairments in thinking abilities. Difficulties in the inhibition and selection between responses (i.e., suppressing the urge to reach for an object, or selecting between objects to grab) have been documented in patients with OCD. These two processes work synergistically, a nd due to the frequent reliance on these functions in daily life, deficits can be debilitating. Further, altered brain electrical activity related to response selection, as measured viaevent-related potentials (ERP), has been found in OCD; this finding is so robust that it has been suggested to indicate a biological identifier for the disorder. However, less is kn own about how altered inhibition in OCD is represented in the brain. To address this gap, this study proposes to compare the performance and ERP activity related to response inhibition and selection in OCD and healthy participants, using the Stop Signal Task (SST), a test in which participants must select between performing and withholding automatic responses. Patients with OCD are expected to show mostly intact performance on the SST, but to exhibit a larger ERP magnitude for response selection, and a smaller ERP for response inhibition compared to healthy participants. A unique discrepancy between altered brain activity despite intact performance on the SST would help clarify the cognitive and biological profiles of OCD. Further, identifying accurate biological indicators of OCD can be used to determine disease presence and potentially treatment efficacy.