Been hit in the head?

My recent copy of Brain in the News had an article about a new test that detects previously unseen brain injuries. A friend of mine and I were talking about concussions recently since he's had three in car accidents (he was hit from behind at a stop but I don't ride with him anyway). Since martial artists get slapped upside the head now and again, I thought this might be of interest.
http://www.komonews.com/news/health/Finding-unseen-damage-of-traumatic-brain-injury-141187333.html?m=y&smobile=y&clmob=y&c=n