Mapping Compulsivity in the DSM - 5 Obsessive Compulsive and Related Disorders: Cognitive Domains, Neural Circuitry And Treatment

Compulsions are repetitive, stereotyped thoughts and behaviors designed to reduce harm. Growing evidence suggests that the neurocognitive mechanisms mediating behavioural inhibition (motor inhibition, cognitive inflexibility) reversal learning and habit formation (shift from goal-directed to habitual responding) contribute toward compulsive activity in a broad range of disorders. In obsessive compulsive disorder (OCD), distributed network perturbation appears focussed around the pre-frontal cortex, caudate, putamen and associated neuro-circuitry. OCD-related attentional set-shifting deficits correlated with reduced resting state functional connectivity between the dorsal caudate and the ventrolateral prefrontal cortex on neuroimaging. In contrast, experimental provocation of OCD symptoms reduced neural activation in brain regions implicated in goal-directed behavioural control (ventromedial prefrontal cortex (vmPFC), caudate) with concordant increased activation in regions implicated in habit learning (pre-supplementary motor area, putamen). The vmPFC plays a multifaceted role, integrating affective evaluative processes, flexible behavior and fear learning. Findings from a neuroimaging study of Pavlovian fear reversal, in which OCD patients failed to flexibly update fear responses despite normal initial fear conditioning, suggest there is an absence of vmPFC safety signaling in OCD, which potentially undermines explicit contingency knowledge, and which may help to explain the link between cognitive inflexibility, fear and anxiety processing in compulsive disorders such as OCD