The medicinal leech, Hirudo verbena, has long been used as a model for the neuronal basis of rhythmic behavior, such as swimming. Swimming is an episodic behavior which can be elicited by brief (1 s) stimulation of the body wall which can produce a single bout lasting 10-30 seconds. Prior research has elucidated a detailed understanding of how the nervous system initiates and generates leech swimming behavior at the level of interactions between specific neurons. What is lacking is an understanding of the neuronal mechanism underlying the transition from brief stimulation to the unique prolonged activity pattern between neurons involved in generating swimming. Previous research has shown that one class of glutamate receptors (non-NMDA) are critical for this transition. My research will continue the lab’s effort to clone and characterize these non-NMDA receptors in order to gain a better understanding of the important role they play in the transition from brief stimulation to prolonged excitation of the leech central nervous system.