Question:
Have you tried contacting the Brain Injury Association? They sent me all sorts of wonderful literature about brain injury. Between that, and the interviews I did, I came to realize just how complex this condition is, and how difficult it is, in subtle and not-so-subtle ways, for the individual (and their friends, family and loved ones) who experience brain injury. Even when it's "mild," it can have a devastating effect on a person's life.

Answer: if you're just looking for the symptoms of a concussion, with no long-term impairment that resulted from the injury, you probably won't have much difficulty coming up with that. I think I jumped the gun when I read the subject line, and thought you were asking about the same kind of impairment I'd been researching, as well.

From what I've read, you don't even have to be knocked unconscious to have suffered a concussion. An excerpt from "Living With Brain Injury: A Guide for Families" by Richard C. Senelick, MD, & Cathy E. Ryan, MA, CCC-SLP:

"The word concussion is more confusing than you might think. On one hand, a concussion is defined as a temporary loss of consciousness. But on the other hand, there doesn't have to be a loss of consciousness at all. "Further, one brain injury predisposes a person to the cumulative effects of subsequent brain injuries. A concussion might be the 'ding' a third baseman hears for 5 to 20 minutes after he's been hit by the ball, or the fumbling of a football quarterback who gets progressively worse after each tackle. The effects are cumulative--as for the 'punch-drunk' fighter who can no longer hit a moving target or even see it. Brief episodes of memory loss may add up to periods of amnesia or permanent memory impairment."