Walter J. Freeman: A Tribute

In the early 1960s, few neuroscientists attempted to model brain function using mathematics. Computers were slow and expensive, so numerical approximations of complex phenomena were out of reach in most cases, and scientists resorted primarily to analytical representations of simpler processes. The study of circuits was not new to Walter J. Freeman. He had started his education studying engineering at MIT (transferring later to the University of Chicago to study English) and was a radio operator in WWII. When he returned from his service, he enrolled in medical school at Yale, where he did his dissertation research under John Fulton. While a postdoc at UCLA in neuropsychiatry, Freeman began to study responses of the olfactory system to shock stimuli. His engineering background and persistent nature led him to the first computational analysis of the olfactory system as a young assistant professor at UC Berkeley. This work carried him from characterizing oscillatory impulse responses and dipole fields within olfactory paleocortical areas in 1959 and the early 1960s to large-scale models of perceptual processing up until the time of his death in April of 2016. Along the way, he was a pioneer in neural networks, introduced the use of nonlinear dynamical systems and chaos theory to study and describe neural systems, and mentored countless scientists worldwide. This work, conducted over 55 years at UC Berkeley, engaged physiologists, physicists, physicians, computer scientists, and philosophers.