he is awake, strumming guitar. >> at least i have principles. >> they don't cost anything. >> you may recognize brad carter from his roles on "true blood" or "csi." but what he's doing offscreen he may be most remembered for. the 39-year-old actor and musician is about to undergo brain surgery to correct a condition called benign central tremors. >> putting off. trying to figure out why this is happening. so hopefully this will help that today. >> the neurological disorder causes carter's hands to shake, to treat it, his doctors at ucla medical center must operate while he's awake. doctors even had carter play guitar during the procedure. strumming the guitar chords helped guide surgeons as they placed an electrode in his brain. >> music is really important to