Correspondence and papers centering on McCulloch's study of the functional organization of the central nervous system and cybernetics. McCulloch (1898-1969) was a major figure in establishing the theoretical ground for modern computers and in "biological computer" studies during the 1960s. Other topics include the brain or neural studies, biological psychiatry, chemical warfare, space biology, and U.S. Army studies. His participation in the American Society of Cybernetics and the Josiah Macy Conferences is well documented, and there are numerous papers and notes on other conferences attended.