Lay Abstract PI: Tierney, Ann Proposal Number: IBN-9707325 All animals perform rhythmic movements, such as walking, chewing and breathing. These movements are produced within the central nervous system by circuits of cells called central pattern generators (CPGs). Neurobiologists have studied CPGs for several decades and have learned a great deal about how these relatively limited circuits program movements. Recent research has shown that even simple circuits are very flexible and can program a wide array of related movements. On a cellular level, this flexibility is produced by neuromodulators, endogenous compounds that alter the activity of individual CPG cells, and consequently alter the output of the circuit. This project describes the distribution of neuromodulatory inputs (including serotonin, dopamine, and two peptides) and investigates how these compounds alter the motor program produced by the two CPGs. Seven species (four from a single genus and three from different genera) will be studied to determine how modulator type, location, or function might change as species and general evolve. This systematic comparison of motor pattern modulation in a set of closely related species is designed to contribute to knowledge of neuromotor system evolution and to the understanding of the coordination of simple rhythmic movements. Simple systems like the ones investigated here are studied in the hope that the underlying mechanisms discovered can be applied to more complicated systems, such as those used in vertebrate locomotor control, including the control of walking in humans.
