Metabotropic glutamate receptors have been implicated in plasticity in the hippocampus and cerebellum. Are they also involved in plasticity in the visual cortex? This is a complicated question because of the diversity of metabotropic glutamate receptors and the variations in both receptors and plasticity with layer. Inhibition driven by group II metabotropic glutamate receptors is certainly correlated with ocular dominance segregation in layer IV of the cortex. Of the group I metabotropic glutamate receptors, mGluR5 may be involved in plasticity, but mGluR1 is unlikely to be. Both group I and group II receptors produce increases in cyclic adenosine monophosphate which are clearly related to plasticity. Further conclusions await the development of agonists and antagonists specific for individual metabotropic glutamate receptors, as opposed to groups of the receptors.
Copyright 1999 John Wiley & Sons, Inc.