One fall day in 1999, on his way to give a lecture, professor Clark Elliott’s car was rear-ended. The impact slammed his head back, then flung it forward. Shaken up but without any noticeable injuries, Clark surveyed the damage to his car, spoke to EMTs called to the scene, then continued on his drive to the DePaul University campus where he taught. He went through the motions but something was off: his mind felt foggy and he couldn’t find his car after class. Later, he had great difficulty gett
