Animals initiate movements either in response to specific stimuli (such as touch, sound or light signals), or as a result of an internal change in state (such as hunger). One important aspect of such voluntary animal movements that has received relatively little attention is their episodic nature, with distinct beginnings and endings. Much is already known about the networks of nerve cells that control rhythmic movements like flying and swimming, but the nervous system components that control the initiation and termination of rhythmic behavior are largely unknown. The experiments funded by this grant are designed to significantly advance the understanding of how nervous systems process information generated by brief sensory stimuli and how they thereby produce episodic locomotion. Experiments will be conducted on isolated central nervous systems of the medicinal leech using two different approaches. One approach is electrophysiological, with experiments to investigate connections among nerve cells that control the initiation and maintenance of swimming movements. The second approach is pharmacological, with studies on the neurohormone serotonin and on other messenger molecules to learn how these substances are involved in converting the quiescent motor system into one that is functionally active. Because there is significant functional similarity between swimming and related locomotory movements in all animals and because the transformation of a system from quiescence to activity and back to quiescence is a feature of all episodic animal movements, insights gained from this research will have a major impact on our understanding of how the nervous system controls animal movements generally. The activities funded by this grant have a broader impact on science by increasing the opportunities for undergraduates, primarily women, to conduct scientific research at Bryn Mawr and at the University of Virginia. Also, experiments conducted in the research laboratory are subsequently incorporated into laboratory exercises for advanced neurobiology courses at both institutions. Finally, training is provided to graduate students in modern electrophysiological recording techniques, data acquisition, and analysis. Results from these experiments are widely disseminated through posters at scientific meetings, including student presentations at local science fairs and scientific meetings; publication in scientific journals; lectures open to the public; and demonstrations on animal behavior at K-12 schools.
