TUCSON, Ariz. — Doctors treating U.S. Rep. Gabrielle Giffords said Monday the congresswoman was responding to verbal commands by raising two fingers of her left hand and even managed to give a thumbs-up.Giffords, 40, is in critical condition in the intensive care unit of Tucson's University Medical Center after she was shot through the head Saturday during a meet-and-greet with voters outside a supermarket.