Specification of Cortical Neurons By Visuomotor Experience

Abstract

Publisher Summary It is generally accepted that the brain is formed during two successive periods of development of the organism. During the first period, neuroembryological events take place, for example, cellular division and migration, neuronal differentiation and the establishment of interneuronal connections. Both the main cerebral structures and the nerve fiber circuits are established following a very rigorous plan and a precise calender of events. This seems to reflect achievement of intrinsic programs under strict genetic control. However, the network, thus established is neither rigid nor stable. Indeed, this first period is followed by a second one mainly postnatal, during which the neuronal connections become stabilized, giving rise to the adult nervous system organization. This second phase is governed by epigenetic factors including the functioning of the brain itself and processes that are dependent on the experience the organism has of its environment. Studies of the ontogeny of the functional organization of the visual cortex have given evidence for this two-stage developmental sequence. Combined progress in electrophysiological and neuroanatomical methods, pioneered mainly by Hubel and Wiesel, have clearly demonstrated that the basic features of the adult cortical organization—namely, binocular integration and orientation selectivity—are present before any interaction with visual environment has taken place.