PLASTICITY OF SOMATOSENSORY CORTEX IN PRIMATES

Over recent years, we have come to the surprising realization that sen sory cortex is highly plastic in functional organization, even in adul t brains. Much of the evidence for this conclusion comes from studies of the effects of peripheral deafferentation or sensory experience on the somatotopy of primary somatosensory cortex (area 3b) of monkeys. L ocal modifications in cortical representations occur rapidly after sen sory loss or more gradually during altered sensory experience. These c hanges depend on reductions in lateral inhibition and other dynamic ad justments in sensory networks, as well as Hebbian-like modifications o f synaptic strengths. Activity-dependent alterations in the expression of neurotransmitters and modulators may also play a role. After major deactivations, such as those produced by amputation or section of dor sal column afferents, cortex regains responsiveness over a much longer time period as a result, at least in part, from the growth of new con nections. (C) 1997 Academic Press.