Simulation of plasticity in the adult visual cortex

Retinal plasticity has been shown in the adult visual nervous system in mam mals. Following a retinal lesion (scotoma) there is a reorganization of the cortical receptive field distribution: cortical neurons selective to visua l stimuli in the area of the visual field corresponding to the retinal lesi on, become selective to other parts of the visual field. In this work, we s tudy this effect with a self-organizing neural network. In a first stage, t he network reaches a pattern of connectivity that represents normal develop ment of neuronal selectivity. The scotoma is simulated by perturbing accord ingly the properties of a region of the input layer representing the retina . The system evolves to a new receptive field distribution mainly by means of the reorganization of the intra cortical connectivity. No major change o f the geniculo cortical connectivity is detected. This may explain the surp risingly short time scale of the event.