A small portion of the brain called the orbitofrontal cortex may be underactive in people with obsessive-compulsive disorder (OCD), according a report in ScienceNow Daily News. Here's a summary of the findings. The full article appears in the current issue of the journal Science.
"[The scientists] monitored 14 OCD patients, 12 unaffected relatives, and 15 people without a family history of the disorder as they engaged in a task intended to stimulate the orbitofrontal cortex. As a functional magnetic resonance imaging machine measured blood flow to various parts of their brains, the participants viewed two superimposed images--a face over a house, for example--on a screen and had to figure out through trial and error which images were "correct" and which ones were "incorrect," as determined by the researchers. Once the subjects caught on to which image was the right choice, the researchers switched it up and made the other image the correct choice. That forced the participants to change their newly acquired habit, something previously shown to activate the orbitofrontal cortex. But although normal subjects exhibited the expected activity in this region, those with OCD and their relatives showed reduced activity, even though their performance on the task was normal."