A car accident, a rough tackle, an unexpected tumble. The number of ways to bang up the brain are almost as numerous as the people who sustain these injuries. And only recently has it become clear just how damaging a seemingly minor knock can be. Traumatic brain injury (TBI) is no longer just a condition acknowledged in military personnel or football players and other professional athletes. Each year some 1.7 million civilians will suffer an injury that disrupts the function of their brains, qualifying it as a TBI.