Neural correlates of anxiety associated with obsessive-compulsive symptom dimensions in normal volunteers.

BACKGROUND: The neural correlates of anxiety associated with obsessive-compulsive symptomlike provocation in normal volunteers are unknown.
METHODS: Ten healthy volunteers participated in four functional magnetic resonance experiments. Subjects were scanned while viewing alternating blocks of emotional (normally aversive, washing-relevant, checking-relevant, or hoarding-relevant pictures) and neutral pictures, and imagining scenarios related to the content of each picture type. Nonparametric brain mapping analyses were used.
RESULTS: In response to the provocative pictures in all experiments, increases in subjective anxiety and activation in bilateral ventral prefrontal, limbic, dorsal prefrontal, and visual regions were demonstrated. Anxiety related to different symptom dimensions was associated with different patterns of activation: provocation of washing-relevant anxiety predominantly activated dorsal and ventral prefrontal regions; checking-relevant anxiety predominantly activated dorsal prefrontal regions; and hoarding-relevant anxiety predominantly activated ventral prefrontal regions and the left amygdala.
CONCLUSIONS: Our findings support a dimensional model of obsessive-compulsive disorder (OCD) whereby 1) the brain systems implicated in the mediation of anxiety in response to symptom-related material in normal subjects are similar to those identified in OCD patients during symptom provocation, and 2) anxiety associated with different symptom dimensions is associated with differential patterns of activation of these neural systems. Further investigation of the neural basis of OCD symptom dimensions is required.