The medicinal leech is a model system used to study the neuronal basis of behaviors such as swimming. A network of neurons has been identified contributing towards leech swimming, and within this system, one class of glutamate receptors (non-NMDA) are the main facilitator of the initiation and generation of swimming behavior. The lab has cloned one full and two partial sequences of non-NMDA receptor subunits from the leech central nervous system. One long-term goal is to determine if neurons comprising the network that initiates and generates swimming express these subunits. Traditionally, this question would be addressed using in situ hybridization probes. Recent studies in the leech and other vertebrate preparations, however, have shown the feasibility of using another technique, quantitative PCR, to determine the expression levels from single, identified neurons. I will apply quantitative PCR to analyze the expression levels of non-NMDA receptor subunits from one to five Retzius cells, which are peripherally associated with swimming, taken from the leech nervous system.