katz professor at weill cornell medical college. and once again my co-herself is dr. eric kandel. he is a nobel laureate, a professor at columbia university d a howard hughes medical investigator. this is going to be fun. tell me, is it really true that one of the great questions is about consciouess? >> it is the greatest question in all of science and certainly the deepest question in all of brain science. and the amazing thing is as we sensed in last year's program that this is an area of knowledge that we thought was very primitive and i think what we're going to learn today is that an amazing amount of progress has occurred in the last decade and a half. we not only have a better unrstanding of unconscious processes but also of conscious processes and of disorders of consciousness. and we're going to learn a lot from this. to begin with, it's important to realize consciousness is not a unitary faculty of mine. there ardifferent stages that range from coma to deep sleep to waking up from sleep to stumblingaround, to recognizing people, to enjoy, being present with people, to i