Marian C. Diamond, Ph.D., is a Professor of Anatomy at the University of California at Berkeley. She teaches general human anatomy and neutoanatomy and has conducted numerous lines of reasearch into the effect of the environment and hormones on the forebrain. Dr. Diamond is perhaps best known for her investigations into structural changes in the cerebral cortex induced by an enriched environment and structural lateralization of the cortex as influenced by sex steroid hormones. Arnold B. Scheibel, M.D., is a Professor of Anatomy and Psychiatry at the University of California Medical School at Los Angeles and a member of the Brain Research Institute. Dr. Scheibel teaches courses in neutosciences and psychiatry. He has published numerous articles on his investigations into the parts of the brain involved in consciousness and higher mental function.