Neurons of the Central Visual System

Abstract

Progressive development of the cerebral cortex in mammals in the course of evolution takes place through many interdependent processes. The surface area of the cortex is increased by the formation of fissures and gyri. The fissures and gyri are formed as a result of an increase in the number of neurons and of their long processes forming the white matter. The mass of white matter is increased, particularly on account of association pathways, and this in turn is connected with an increase in the number of pyramidal cells in the cortex. Considerable differentiation takes place in the cortex, with the appearance of new areas and subareas and their corresponding new connections, for thousands of association, commissural, and projection fibers arise from every point of the cortex. As the brain develops, and increases in complexity in response to adaptation to the external environment, the number of layers in the cortex changes. Changes in the architectonics of the brain and in the structure of its layers are a manifestation of neuronal specialization corresponding to the areas and lobes of the brain.