These days, we hear a lot about a term called traumatic brain injury, and what is a traumatic brain injury or TBI as we refer to it. And that is actually any injury to the brain that originates from an external force, like a blow to the head, something that comes outside the brain itself and affects the brain. So if you're playing sports, this could be, you do a header in soccer where the ball hits the top of your head. It could be another player. In our military today, we hear a lot about the IED blast or the blast wave from the improvised explosive device. And that too can cause a brain injury from an external force. So when you hear the term TBI, you're thinking of anything that comes from the outside and greatly affects the brain on the inside.