here to discuss how we perceive and process pain, david bar stiewk of children's hospital and david julius of the university of california, san francisco, allan basbaum, also of the university of california san francisco, robert dworkin of the university of rochester and once again my cohost dr. eric kandel a nobel laureate, and a howard hughes medical investigator. >> our subject is pain. hrchl is really one of the great unmet medical needs and enormous problem in society. and the most, in the most general terms, bain is a unpleasant sensation in response to a real or potential threat of body injury, and it has an extremely important defensive damnive role, it is designed to remove the injured part of the body from the source of damage. and usually this is transient in nature, but with some diseases, such as cancer or arthritis, it becomes persistent and becomes not an damnive process but, adaptive process and part of the disease itself and adds to the pain .. as we will hear from laurie klein, chronic pain is a disease in its own right. as these arguments make clear, this is an enormous