Mechanisms for acute changes in sensory maps.

Many studies have examined changes in the topographic representations of the special senses in cerebral cortex following partial peripheral deafferentations. This approach has demonstrated the short- medium- and long-term aspects of plasticity. However, the extensive capacity for immediate plasticity, while first demonstrated more than 15 years ago, still challenges explanation. What such studies indicate is that each locus in sensory cortex receives viable input from a far wider area of the sensory epithelium than is represented in the normal receptive field, with the implication that much of this input is normally inhibited. Consideration of the geometric and temporal aspects of receptive field plasticity suggests that this inhibition must be tonic and must derive its driving input from a tonically active periphery.