McCulloch, Warren S.

Warren McCulloch (1898-1968) was a physician turned physiologist. After medical school, he trained in neurology from 1928 - 1931, studied mathematical physics in 1931 - 1932, worked as a clinician from 1932 - 34, then joined the Yale Laboratory of Neurophysiology and by 1941 became an assistant professor in the department. His main work at Yale was on the functional connections in the CEREBRAL CORTEX of primates. Dusser de Barenne, his mentor and collaborator, had developed the method of strychnine neuronography, a way of determining the direct projection of one architectonically specified region in the cortex of the forebrain to other regions. It is a clever and reliable technique that served well to show in a single day of experiment what would take years to work out by the standard anatomical procedures at the time. Little of what the technique revealed has been faulted, but it never caught on for a variety of reasons, the main one being a general misunderstanding of the underlying physiology.

In 1941 McCulloch came to the Illinois Neuropsychiatric Institute as Associate Professor of Psychiatry at the College of Medicine, University of Illinois. Percival Bailey, Professor of Neurosurgery, had worked with McCulloch at Yale, as had Gerhardt van Bonin, Professor of Anatomy. The neuronography of primate cortex work continued and attracted many visiting collaborators, and McCulloch developed an enduring interest in the bulbo-reticular system, due mainly to the innovative studies of Magvin and Snyder at Northwestern University.

In 1942 he took a medical student, Jerry Lettvin, together with his friend Walter PITTS, into his laboratory, and by midyear, into his home. Pitts, taking an interest in the nervous system, told McCulloch of Gottfried Wilhelm Leibniz's dictum that any task that can be completely and unambiguously set forth in logical terms can be performed by a logical engine. In the previous year, David Lloyd had demonstrated monosyllabic excitation, facilitation, and inhibition. And in 1936-37 Alan TURING had published his brilliant essay on the universal logical engine. It seemed to McCulloch and Pitts that neurons could be conceived as logical elements, pulsatile rather than two-state devices, and capable of realizing logical process. The ensuing paper, "A Logical Calculus of the Ideas Immanent in Nervous Activity" (McCulloch and Pitts 1943) became the inspiration for a new view of the nervous system, and a justification for the project of artificial intelligence.

In a later second paper, "On how we know universals: The perception of auditory and visual forms," Pitts and McCulloch implemented their notions by showing how the anatomy of the cerebral cortex might accommodate the identification of form independent of its angular size in the image, and other such operations in perception.

McCulloch at the same time carried on a full load of his studies in the physiology of the cortex and other parts of the nervous system. That was his daytime work. But, having become enamored of LOGIC, his evenings were devoted to problems in logical representation of mental operations. After all, he had developed a profound interest in philosophy while at Yale.

By the end of the 1940s, with John VON NEUMANN's first digital computers, Norbert Wiener's linear prediction theory, and the massive and singularly intellectual thrust of the military and industrial complex, it was evident that a new era was opening. In 1951, Jerome Wiesner, on Norbert Wiener's advice, offered a place at the Research Laboratory of Electronics at MIT to McCulloch, Pat Wall, and Lettvin. There McCulloch and Wall worked on spinal cord physiology. Pitts was already at MIT. At the time McCulloch was full professor at the University of Illinois, and Wall was assistant professor at the University of Chicago. Although the move brought loss of academic status and a serious cut in pay, the three of them accepted the invitation.

Beginning in 1951, McCulloch became a magnet for a most diverse company of those concerned with the new communications revolution. Benoit Mandelbrot, Manuel Blum, Marvin Minsky, Seymour Papert, and a host of others, then young and eager and hungry for discovery, visited frequently and stayed for long discussions.

Several major works were issued before 1960. One that charmed McCulloch particularly was the arduous source-sink analysis of currents in the spinal cord. Pitts had laid out the general method behind the effort; published in 1954-1955, it was the first demonstration of presynaptic inhibition between the collaterals of dorsal root fibers. A year and a half had been spent on computations that would occupy about an hour on today's machines. Then there was the demonstration of the action of strychnine, which provided the ground needed to justify strychnine neuronography. Wall turned his interest to the mechanism involved in pain. H. R. Maturana joined the group from Harvard and, thanks to his patience and skill, "What the Frog's Eye Tells the Frog's Brain" was published (Lettvin et al. 1959).

Bob Gesteland joined the group as McCulloch's graduate student, addressing himself, under the urging of Pitts and McCulloch, to the problem of olfaction. His were the first recordings of the activity of single olfactory cells in the nasal mucosa of frogs. And his results -- namely, that every cell responds to almost every odorant but with different coding patterns of activity, for different odorants, and that cells differ among themselves in their coding patterns for the odorants -- are just bearing fruit today. In short, McCulloch was the center of a new thrust in nervous physiology, even more fascinating than what he envisioned before coming to MIT.

McCulloch had great generosity of spirit. He treated everyone as an equal and made an effort to encourage the best in everyone he met. He never showed the faintest hint of malice or envy or deviousness, but spoke, wrote, and carried himself as a nineteenth-century cavalier. A complete list of his publications is given in his Collected Works, and a small indication of his influence is evidenced by the Further Readings below.

See also

Additional links

-- Jerome Lettvin


Lettvin, J., H. Maturana, W. McCulloch, and W. Pitts. (1959). What the frog's eye tells the frog's brain. Proceedings of the IRE 47:1940-1959. Reprinted in Embodiments of Mind.

McCulloch, R., Ed. (1989). Collected Works of Warren S. McCulloch. 4 volumes. Salinas, CA: Intersystems Publications.

McCulloch, W. S. (1988). Embodiments of Mind. Cambridge, MA: MIT Press. Originally published 1965.

McCulloch, W., and W. Pitts. (1943). A logical calculus of the ideas immanent in nervous activity. Bulletin of Mathematical Biophysics 5:115-133. Reprinted in Embodiments of Mind.

Pitts, W., and W. McCulloch. (1947). On how we know universals: The perception of auditory and visual forms. Bulletin of Mathematical Biophysics 9:127-147. Reprinted in Embodiments of Mind.

Further Readings

Anderson, J. A. (1996). From discrete to continuous and back again. In Moreno-Diaz and Mira-Mira (1996).

Arbib, M. A. (1996). Schema theory: From Kant to McCulloch and beyond. In Moreno-Diaz and Mira-Mira (1996).

Cull, P. (1996). Neural nets: Classical results and current problems. In Moreno-Diaz and Mira-Mira (1996).

Lettvin, J. (1988). Foreword to the 1988 reprint of Embodiments of Mind.

Lettvin, J. (1989). Introduction to vol. 1. R. McCulloch, Ed., Collected Works of Warren S. McCulloch.

Lindgren, N. (1969). The birth of cybernetics -- an end to the old world: The heritage of Warren S. McCulloch. Innovation 6:12-15.

Moreno-Diaz, R., and J. Mira-Mira, Eds. (1996). Brain Processes, Theories and Models: An International Conference in Honor of W. S. McCulloch 25 Years after His Death. Cambridge, MA: MIT Press.

Papert, S. (1965). Introduction to Embodiments of Mind.

Perkel, D. H. Logical neurons: The enigmatic legacy of Warren McCulloch. Trends in Neuroscience 11:9-12.

Weir, M. K. (1996). Putting the mind inside the head. In Moreno- Diaz and Mira-Mira (1996).