Dr. Stuart Hameroff, anesthesiologist and philosopher, is the co-creator, along with Dr. Roger Penrose, of the Orch-OR (Orchestrated Objective Reduction) theory of consciousness. Orch-OR postulates consciousness as a quantum phenomenon located mainly in the microtubules of the brain. As coherent quantum information, consciousness can exist outside the brain, possibly indefinitely, retaining its unique identity, and might even be able to enter a new brain, accounting for reincarnation. Orch-OR may be unique in that it may be the only materialistic explanation for consciousness that can account for survival after death and the effects of psychedelic drugs and intense states of meditation. Dr. Hameroff also proposes an experiment for testing the hypothesis, involving different regimens of anesthetic drugs.
Dr. Hameroff explains the Orch-OR model in greater detail in this one hour interview.