Aging is one of the most universal and inevitable social and sci entific challenges confronting man. The lives of all multicellular organisms begin with conception, extend through phases of development, maturity, senescence and finally end in death. Man is no exception, but has the unique feature of a complex brain. It plays an integra tive role in adaptation to the physical and social environments through reflexes, conditioning and more complex forms of learning. The brain is a repository for both inherited and acquired information. With the development of speech and the formation of...