The goal of this project is to study the NMDA receptor in development and developmental plasticity. We will examine the development of the NMDA receptor complex in olfactory and hippocampal circuits in relationship to the critical periods for olfactory learning. We will also pursue studies on the action of NMDA antagonists in early olfactory glomerular plasticity. This will consist of identifying the minimal period of administration, the use of newly developed and highly specific analogues, and the direct administration of compounds into the brain. Collaborative projects are proposed to investigate the relationship between NMDA receptor activation, other neurotransmitter systems, and early learning.