INDUCTION OF LTD BUT NOT LTP THROUGH METABOTROPIC GLUTAMATE RECEPTORSIN VISUAL-CORTEX

LONG-term potentiation (LTP) and long-term depression (LTD), often use d as essential components in synaptic models for learning, memory and forgetting, can be produced in cortical tissue by repetitive activatio n of neural pathways under different stimulus conditions. The involvem ent of metabotropic glutamate receptors (mGluRs) has been postulated t o be necessary for the establishment of either or both forms of synapt ic plasticity in hippocampus. The recent introduction of a specific an tagonist for mGluRs, (+/-)-alpha-methyl-4-carboxyphenl-glycine, prompt ed the investigation of the respective involvement of this receptor po pulation in the induction of LTP and LTD in visual cortex of the rat i n vitro. The results suggest the critical involvement of mGluRs in pro ducing LTD but not LTP.