Figure 4.

Theoretical model of how dysregulated information processing in corticolimbic inputs to ventral striatum could underlie compulsive behavior in OCD. Each of the corticolimbic inputs highlighted in this review are depicted in the left column. VS is depicted in the right column for illustrative purposes. Bulleted text highlights information that is processed by each input region, and could theoretically be a source of dysregulated information processing in VS of OCD patients. (A) Value comparisons and decision-making are important functions of mOFC. Aberrant representations of this information could lead individuals with OCD to improperly evaluate behavioral choices. This could, in turn, lead to inflated valuation, and subsequent selection of compulsive behaviors. Alternatively, these aberrant representations could render goal-directed decision making ineffective, and bias behavioral control toward habit-like selection of compulsive behaviors. (B) The amygdala processes threatening/fearful stimuli, rewarding stimuli, and aversive stimuli. Aberrant representations of this information in OCD could lead to improper behavioral selection and compulsive behavior. As summarized in the text, amygdala is often hypoactive in response to rewarding or neutral stimuli, and hyperactive in response to threatening or symptom-provoking stimuli, which could lead to excessive influence of these stimuli over behavior. This is consistent with clinical observations of provocation of compulsive behaviors by environmental stimuli that are perceived as threatening. Amygdala projections to VS are particularly important to Pavlovian instrumental transfer (PIT). Symptom provoking stimuli could theoretically acquire an influence over behavior through PIT, and thus, dysregulation of PIT could also contribute to OCD. Amygdala is also important for processing anxiety, which is associated with the generation and/or maintenance of compulsive behaviors in OCD; this link places special emphasis on amygdala-based information processing in OCD. (C) The VTA is a major source of dopamine input to VS, and processes reinforcement signals which inform behavioral selection. This input is also necessary for sustaining behavioral sequences and effortful behavior. Considerable evidence suggests that OCD is associated with dysregulation of the dopamine system, potentially leading to a hyperdopaminergic state. These disruptions would theoretically impact information processing necessary for selecting and sustaining behavioral sequences, and could promote compulsive behavioral patterns. VTA input to VS is also necessary for PIT, and a hyperdopaminergic state could also contribute to the ability of environmental stimuli to impact behavioral selection in OCD.