9513896 Udin This award supports collaboration between Dr. Susan Udin, SUNY, Buffalo, and Dr. Tsai Haojan, Beijing Medical University, China on patch-clamp studies ofApril 22, 1996 cholinergic transmission in the tectum. The CNS contains a multiplicity of nicotinic and muscarinic receptor subtypes, but many gaps remain in the understanding of how these receptors contribute to physiological response of the cells that receive cholinergic inputs. One way to begin to assess the contribution of those receptors is to study to the responses of neurons in the frog optic tectum. The frog tectum is particularly suitable because it has an unusually restricted population of cholinergic axons, all of which are derived from the nucleus isthmi. Whole-cell patch clamping will be used to identify tectal cells that respond to cholinergic agonists. The distribution and morphology of the cells will be revealed by biocytin filling. The results will help to clarify the contribution of cholinergic processes in central nervous system neurons. In addition, these experiments with Rana will provide data for comparison with results of the similar experiments in Xenopus frogs; this comparison is of interest because the cholinergic axons that project to the Xenopus tectum from the contralateral nucleus isthmi display dramatic plasticity during a critical period of development of the cholinergic axons, whereas such plasticity is absent in Rana.
