Warren Sturgis McCulloch was born in Orange, New Jersey and studied at Yale (philosophy and psychology) and Columbia (psychology). Receiving his MD in 1927 from the College of Physicians and Surgeons in New York he undertook a internship at Bellevue Hospital, New York before returning to academia in 1934.
He is remembered for his work with Dusser de Barenne (Yale) and later Walter Pitts (Illinois) which provided the foundation for certain brain theories in a number of classic papers, including "A logical calculus of the ideas immanent in nervous activity" (1943) and "How we know universals: the perception of visual and auditory forms" (1947), both in the Bulletin of Mathematical Biophysics. In the 1943 paper they demonstrated that a Turing machine program could be implementated in a finite network of formal neurons, that the neuron was the base logic unit of the brain. In the 1947 paper they offered approaches to designing nervous nets to recognize visual inputs despite changes in orientation or size.
From 1952 he worked at the MIT Research Laboratory of Electronics, working primarily on neural network modelling. His team examined the visual system of the frog in consideration of McCulloch's 1947 paper, discovering that the eye provides the brain with information that is already, to a degree, organized and interpreted, instead of simply transmitting an image. McCulloch also posited the concept of "poker chip" reticular formations as to how the brain deals with contradictory information in a democratic, somatotopical neural network.
He was a founder member of the American Society for Cybernetics and its first president from 1967-1968. He was a mentor to the British operational research pioneer Stafford Beer.