GREY'S ANATOMY - "Losing My Mind" - Dr. Wyatt refuses to let Meredith give up on therapy, Alex learns the truth about Rebecca's medical condition, the Chief insists that Erica perform a risky surgery on his mentor, and after receiving news of Burke, Cristina continues to do things contrary to her nature, going so far as cleaning her always-messy apartment, on "Grey's Anatomy," THURSDAY, MAY 15 (9:00-10:02 p.m., ET) on the ABC Television Network. (ABC/MITCH HADDAD) ELLEN POMPEO, APRIL GRACE, PATRICK DEMPSEY