Developmental regulation of synaptic mechanisms that may contribute to learning and memory

The cerebral cortex is able to undergo dramatic adaptive functional changes in response to a variety of challenges such as sensory experience, pattern ed vs. chaotic environmental cues, training, learning, and peripheral or ce ntral nervous system injury. The period of early postnatal development is p articularly conducive to such changes although the adult cortex can also ex hibit robust plasticity. A major site of these forms of adaptive changes is the cortical synapse. In this study, we examine the ability of cerebral co rtical synapses, particularly in the visual cortex, to undergo changes in t heir functional strength in response to a particular model of synaptic lear ning-the covariance or BCM model. This model incorporates the demand for in coming synaptic activity and the level of activation of a target or postsyn aptic neuron to correlate or covary A dramatic switch in the underlying cel lular signaling mechanism for this form of synaptic plasticity occurs durin g postnatal development. The neurotransmitter receptor mechanism that trigg ers the plasticity switches from one mediated by metabotropic glutamate rec eptors to a NMDA glutamate receptors mediated process. The implications of this switch for developmentally regulated cortical synaptic plasticity a re considered. (C) 1999 Wiley-Liss, Inc.