Donald Hebb

Richard E. Brown

The Organization of Behavior has played a significant part in the development of behavioural neuroscience for the last 70 years. This book introduced the concepts of the “Hebb synapse”, the “Hebbian cell assembly” and the “Phase sequence”. The most frequently cited of these is the Hebb synapse, but the cell assembly may be Hebb’s most important contribution. Even after 70 years, Hebb’s theory is still relevant because it is a general framework for relating behavior to synaptic organization through the development of neural networks. The Organization of Behavior was Hebb’s 40th publication. His first published papers in 1937 were on the innate organization of the visual system and he first used the phrase “the organization of behavior” in 1938. However, Hebb wrote a number of unpublished papers between 1932 and 1945 in which he developed the ideas published in The Organization of Behavior. Thus, the concept of the neural organization of behavior was central to Hebb’s thinking from the beginning of his academic career. But his thinking about the organization of behavior in 1949 was different from what it was between 1932 and 1937. This paper examines Hebb’s early ideas on the neural basis of behavior and attempts to trace the rather arduous series of steps through which he developed these ideas into the book that was published as The Organization of Behavior. Using the 1946 typescript and Hebb’s correspondence we can see a number of changes made in the book before it was published. Finally, a number of issues arising from the book, and the importance of the book today are discussed.

G. Shaw

J. Wagner-Carena, S. Kate, T. Riordan, R. Abbasi-Asl, J. Aman, A. Amster, AL Bodor, D. Brittain, JA Buchanan, MA Buice, DJ Bumbarger, F. Collman, NM da Costa, DJ Denman, S. de Vries, E. Joyce, D. Kapner, CW King, J. Larkin, J. Lecoq, G. Mahalingam, D. Millman, J. Mölter, C. Morrison, R. Reid, CM Schneider-Mizell, S. Daniel, S. Suckow, Kevin Takasaki, Marc M. Takeno, R. Torres, D. Vumbaco, J. Waters, D. Wyrick, W. Yin, J. Zhuang, S. Mihalas, S. Berteau

In 1949, Donald Hebb proposed that groups of neurons that activate stereotypically form the organizational building blocks of perception, cognition, and behavior. Finding the structural underpinning of such assemblies has been technically challenging, due to a lack of large-scale structure-activity maps. Here, we analyze this relation using a novel dataset that links in vivo optical physiology to connectivity using postmortem elec-tron microscopy (EM). From the fluorescence traces, we extract neural assemblies from higher-order correlations in neural activity. Physiologically, we show that these assemblies exhibit properties consistent with Hebb’s theory, including more reliable responses to repeated natural movie inputs than size-matched random ensembles and superior decoding of visual stimuli. Structurally, we find that neurons that participate in assemblies are significantly more integrated into the structural network than those that do not. Contrary to Hebb’s original prediction, we do not observe a marked increase in the strength of monosynaptic excitatory connections between cells participating in the same assembly. However, we find significantly stronger indirect feed-forward inhibitory connections targeting cells in other assemblies. These results show that assemblies can be useful components of perception, and, surprisingly, they are delineated by mutual inhibition.

G. Shepherd

Kadir Can, Erhan Nalçacı

This study examines the emergence of The Organization of Behavior (1949) and the neuropsychological theory of Donald O. Hebb—a landmark contribution to the history of neuroscience and the psychology of learning—in parallel with his biography and academic development. The article evaluates Hebb's academic career, shaped across Dalhousie, McGill, Chicago, Harvard, Queen's, and Yerkes, alongside the intellectual influences of scientists such as Lashley, Köhler, Penfield, and Lorente de Nó. It investigates how Hebb's neuropsychological theory, grounded in the postulates of cell assemblies and phase sequences, took form through experimental work aimed at explaining the neurological and physiological bases of learning, through theoretical inquiry, and through the interplay of different scientific traditions. Emphasis is placed on Hebb's account of learning as a dynamic process shaped by the interaction of hereditary and environmental factors, and on his integrative framework bridging behaviorist reductionism and cognitive approaches. The influence of the Hebbian synapse concept on contemporary research in long-term potentiation (LTP), spike-timing dependent plasticity (STDP), neuroplasticity, and neurocomputational modeling is also addressed. In the conclusion, Hebb's neuropsychological theory is assessed as a significant theoretical development offering a biologically grounded account of the mind–body problem.