Substitution of visual by auditory inputs in the cat's anterior ectosylvian cortex.

Long-term visual deprivation from birth leads to reorganization of the anterior ectosylvian region of the cat's cortex. A visual area in the fundus of AES, area AEV, in which neurons normally respond briskly to visual stimuli, is taken over almost completely by auditory and somatosensory inputs. Auditory neurons are sharply tuned to the location of a sound source in azimuth. A higher than normal proportion of neurons in the AES of visually deprived cats responds to multimodal stimuli. Takeover of visual regions by non-visual inputs can be explained by the same mechanisms that are invoked for developmental plasticity within the visual system: neural activity and competition between different inputs leads to changes in synaptic efficacy. Additional sprouting cannot be excluded. The radical changes of sensory modality within the AEs, caused by visual deprivation, suggest that the same code is used by visual, auditory and somatosensory maps in this region to represent the sensory environment and lead to sensorimotor transformation.