ABSTRACT
Obsessive-compulsive disorder (OCD) is a common neuropsychiatric illness characterized by intrusive, repetitive thoughts and ritualistic behaviors that cause marked distress. Common symptoms include harm-related fears with checking compulsions; contamination fears with cleaning compulsions; symmetry obsessions with arranging and repeating compulsions; and hoarding and saving compulsions. OCD affects 2-3% of the population worldwide1
and can cause significant disability and functional impairment.2 Effective treatments for OCD include serotonin reuptake inhibitor (SRI) medications3
and cognitive-behavioral therapy (CBT).4 Because OCD symptoms tend to be chronic, relatively consistent over time, and reliably reproducible, it has been possible to study them with a variety of neuroimaging techniques in an effort to determine how the brain mediates their expression.5
