post-traumatic stress problem based on that accident. >> larry: what is post-traumatic stress? something happens to you and -- >> and you experience hyper vigilance, heightened levels of stress and you have behaviors in your life that are so difficult, that they make your life difficult to navigate after that. we see it obviously in wartime. after trauma, abuse, rape. and after things like car accidents. >> larry: we didn't hear it until vietnam. >> it was shell shock. it had different names. we still -- >> one thing about this case, ptsd can create all of those symptoms, as well as triggering panic attacks. you have one trial learning when you're in a situation that's highly negative and you imprint on that and then you have a problem driving in snow because you have an association. >> larry: how do you get rid of it? >> the desensitization method. >> but it locks things in. the parts of the brain is walled off from other parts. we have to function flexibility as an entire brain.