Lorente de Nó and the Hippocampus: Neural Modeling in the 1930s

Abstract

Lorente de Nó’s substantial contributions to our understanding of the structure and function of the hippocampus are largely contained in a single, extensive paper that was published in 1934 in the Journal fü r Psychologie und Neurologie (Lorente de Nó,’ 34) while he was working at the Central Institute for the Deaf in St. Louis, Missouri (USA), although most of the drawings in the paper were dated 1927 or 1928, during a period when he was in Spain. The experimental work underlying this paper dealt with the cellular organization (cytoarchitecture) and connections of the hippocampus in the mouse, monkey, and human brain, and contributions emerging from this analysis may be divided in factual and theoretical components. As we shall see, Lorente de Nó advanced our knowledge of hippocampal circuitry in several important ways. However, his real genius emerged from theoretical considerations of the physiology of individual neurons and then of interconnected groups of neurons. From this he made the remarkable prediction that conduction in axons and dendrites must be fundamentally different: while conduction in axons is by way of all-or-none impulses that are followed by a refractory period, conduction at dendrites was predicted to be subthreshold, additive, and nonrefractory. In short, he proposed that the neuron is a summation apparatus that generates a pattern of impulses in the axon. And this was only the highlight of the paper; many other profound issues were raised and dealt with in a more or less complete way.