ABSTRACT
Like most neuropsychiatric disorders, the development of brain-behavior models of obsessive-compulsive disorder (OCD) has been characterized by variability. The variable results are most likely to be due to the small sample sizes that characterize most studies, the large number of comparisons made without adjustment of Type I error rates, and poor inclusion and exclusion criteria. These factors are common in psychiatric research, and their effects in obscuring true differences between the population of patients with OCD and healthy controls are exacerbated by the variability in the presentation of the psychiatric illness itself. However, when the field is viewed from a broader perspective, a convergence of neuropsychological, psychopharmacological, neuroimaging and behavioral approaches becomes evident. The disorder appears to involve both the basal ganglia (specifically the caudate nucleus) and the orbitofrontal cortex (OFC), and probably the direct and indirect interconnections between these two regions. Both the serotonergic and dopaminergic systems are involved in OCD, although, as with the functional neuroimaging studies, it is still difficult to disentangle the relationship between abnormal function, obsessive-compulsive symptoms and general anxiety. Cognitive impairment is subtle in OCD and, in the main, is not characterized by perseverative responding or general failures of inhibition. These impairments can be described parsimoniously as an inability to guide behavior on the basis of an internal and non-verbal representation of the task information. Cognitive impairments become greater and more reliable when neuropsychological task performance depends upon function in the OFC. Interestingly, these tasks also generally contain an emotional or social dimension. Therefore, these factors must be taken into account before more complete brain-behavior models of OCD can be developed. However, advances in the cognitive neuroscience and neuropsychology of emotion and social cognition provide a sound foundation for this endeavor.
