question posted on our facebook page. do we know what part of the brain causes obsessive compulsive behavior? >> there's a lot of imaging work with that. what we see in the prefrontal cortex, rather than being low, what we see in impulsive disorders, the prefrontal cortex works way too hor with people with ocd. some of the medicines we use or therapies we use actually calm down the prefrontal cortex, so people don't think about things over and over again. >> larry: we've posted to the "larry king" facebook page asking for questions on the brain. 12 years ago i got into an accident in the snow. i don't drive in the snow anymore. i'm a terrified passenger if it's snowing. i've become paralyzed. i cry. i know it's irrational. what's going on with my brain? cara? >> it sounds like it could be a