GREY'S ANATOMY - "What I Am" - Addison doubts her abilities as a doctor, Cristina pushes Burke's rehabilitation, one of the interns suffers their own medical emergency, and Izzie receives the surprise of her life, on "Grey's Anatomy," THURSDAY, OCTOBER 12 (9:00-10:01 p.m., ET) on the ABC Television Network. (ABC/GALE ADLER) KATHERINE HEIGL, FRED WARD