THE NATURE OF SYNAPTIC PLASTICITY IN THE VISUAL-CORTEX OF KITTENS - AN ELECTROPHYSIOLOGICAL ANALYSIS INVITRO

The chapter describes experiments designed to investigate the factors leading to the expression of long-term synaptic plasticity in slices of visual cortex from kittens of various postnatal ages. It is reported that low-intensity and low-frequency tetanic activation of the white matter underlying visual cortex in young animals, produces changes of certain electrophysiological measures recorded intracellularly, such as diminished excitatory post-synaptic potential (EPSP) amplitudes, long-lasting depolarization of membrane potential and decreased threshold. These findings explain the rather paradoxical observation from early studies, that post-tetanic synaptic responses measured from extracellular field potentials are diminished in amplitude, rather than enhanced. In the visual cortex of the kitten, there is a phase of post-natal development called the critical period, during which the use of dependent modifications of neuronal response properties are inducible by altering the nature of, or amount of, photic experience arriving through visual inputs. © 1993, Academic Press Inc.