Quantum Leap S03E22 - Shock Theater - October 3, 1954

Leaping into Sam Bederman, a mental patient who is suffering from acute depression, Sam receives an overloaded electroshock treatment, which causes his Swiss-cheesed memory to be replaced by personas from previous leaps. Al, finding himself visible to the mentally absent, must try to complete Sam's mission, and convince him to take another shock treatment, in order to leap Sam out before contact is lost forever.