Overview

It is widely believed that much of the learning and resulting organization of the central nervous system occurs due to modification of the efficacy or strength of at least some of the synaptic junctions between neurons, thus altering the relation between presynaptic and postsynaptic potentials. The vast amount of experimental work done in visual cortex particularly area 17 of cat and monkey strongly indicates that one is observing a process of synaptic modification dependent on the information locally and globally available to the cortical cells. Furthermore, it is known that small but coherent modifications of large numbers of synaptic junctions can result in distributed memories [Cooper, 1973; McClelland et al., 1986] Whether and how such synaptic modification occurs, what precise forms it takes, and what the physiological and/or anatomical bases of this modification are, the questions we would most like to answer.

There is no need to assume that such mechanisms operate in exactly the same manner in all portions of the nervous system or in all animals. However, one would hope that certain fundamental similarities exist so that a detailed analysis of the properties of these mechanisms in one preparation would lead to conclusions that are generally applicable.

Because of its great complexity, visual cortex would not seem to be an auspicious region of the brain to carry out an investigation of synaptic plasticity or of the mechanisms and sites of memory storage. It is almost certain that much of the architecture of visual cortex is preprogrammed...