LONG-TERM POTENTIATION AND GLUTAMATE RELEASE IN THE DENTATE GYRUS - LINKS TO SPATIAL-LEARNING

Long-term potentiation (LTP) in the dentate gyrus of the anaesthetized rat is associated with a persistent increase in the concentration of glutamate in the extracellular compartment. At the in vitro level, thi s is mirrored by an increase in the ability of slices or synaptosomes from potentiated tissue to release glutamate in response to a depolari zing stimulus. In both cases, the activity-induced enhancement of glut amate release is dependent on the activation of the NMDA receptor. A s imilar increase in glutamate release in vitro is observed in the denta te gyrus prepared from rats trained in a variety of learning tasks, in cluding classical conditioning and the Morris water maze. These result s are consistent with the hypothesis that similar presynaptic mechanis ms are engaged in LTP and learning.