dr. eric kandel. a noubl lawyer yet, professor at columbia university and a howard hughes medical investigator. i am pleased to have all of them here this evening at this table. which begin as we always do talking to eric kandel. what are we doing this evening. >> post traumatic stress disorder. this is a fascinating disorder. and it is unique in psychiatry. it is perhaps the only psychiatric disorder whose cause we really understand well. post traumatic stress disorder is a response to the physical threats to the integrity of one's self or someone else. it is associated with feeling of tremendous fear and helplessness. we are privileged to have john o'brien with us today who can tell us directly what it's like to experience post traumatic stress disorder. as you pointed out he's an american hero. he just retired from being lieutenant colonel in the army. and served 25 years of duty including service in iraq where he first developed post traumatic stress disorder. post traumatic stress disorder as you