This book brings together some of the results and ideas produced by a large number of people-colleagues and students with whom I am privileged to work in the laboratory at Rockefeller University. In terms of my personal history I see it as a confluence of creative forces- persons from whom I have learned. I was instructed in neuroanatomy by Walle J. H. Nauta at M. I. T., and later in a course at Harvard Medical School under the direction of Richard...