Long-term modifications of unit activity in area 7 of the cat neocortex after unilateral division of the optic radiation

Abstract

Changes in functional characteristics of cells in area 7 of the cat parietal cortex at different times after unilateral division of the optic radiation were studied in semichronic experiments. Neuronal responses were studied in the affected and intact hemispheres to adequate stimuli of different modalities and to direct electrical stimulation of the primary neocortical projection zones. In area 7 on the side of the operation neuronal sensitivity to stimuli of different sensory modalities were restored. In area 7 of the intact hemisphere the number of cells with local receptive fields gradually increased after the operation and the average size of the receptive fields also increased. It is concluded that mechanisms of plasticity of the partietal association cortex are based on the ability of cells of this zone to receive impulses, via the system of intracortical association fibers, from other sensory or nonspecific brain systems, and also their ability to reorganize their firing pattern depending on changing internal and external environmental conditions.