Possible Synaptic Mechanism Subserving Learning

  • J. C. Eccles


The most important generalizations that can be made about the central nervous system are that it is composed of an immense number of individual nerve cells or neurones and that these individuals are organized into functional assemblages by the synaptic contacts that they make with each other. For example, Fig. 1 A shows a drawing by Ramón y Cajal (1911) of eight neurones in the three surface layers of the frontal cortex of a month-old child. The body or soma of each neurone gives off elaborately branching dendrites covered with a wealth of small spines, and also a single fine axon process having many branches that are destined to make synaptic contacts on other neurones. No synaptic connections are seen in Fig. 1 A, but a wide variety is shown in Fig. 1 B that was drawn by Hamlyn (1963) on the basis of electron microscopic pictures. The small terminal branches from other neurones are shown making close contacts (synapses) with the soma and dendrites of this pyramidal cell of the hippocampal cortex, and the details of synaptic structure are shown in the various enlargements to the right. For our present purpose it is sufficient to recognize that there is a complete separation between the presynaptic terminals and the post-synaptic membrane on which they make contact, there being actually a narrow separating space, the synaptic cleft.


Pyramidal Cell Dendritic Spine Parallel Fiber Apical Dendrite Climbing Fiber 
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Copyright information

© Springer-Verlag Berlin · Heidelberg 1972

Authors and Affiliations

  • J. C. Eccles
    • 1
  1. 1.Department of PhysiologyState University of New YorkBuffaloUSA

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