This project will study and compare the membrane properties of somas and synaptic terminals in embryonic chick Edinger Westphal neurons. These neurons are unique among vertebrate preparations in that both cell bodies and terminals can be studied directly using electrophysiological techniques. Comparison of Edinger Westphal cell bodies and terminals may reveal patterns of differential receptor and channel distribution that will increase our understanding of how membrane properties subserve neuronal function. The first objective will be to study the membrane properties of neurons in the Edinger Westphal nucleus using intracellular impalements in a slice preparation. Both passive and active membrane characteristics will be studied including voltage sensitive currents. In addition, chemosensitivity to a variety of putative neurotransmitters will be examined. The second objective will be to study the membrane properties of the calyciform synaptic terminals formed by Edinger Westphal neurons on targets in the ciliary ganglion. As in the slice preparation, intracellular impalements, both current clamp and single electrode voltage clamp, will be used. Passive and active membrane properties and chemosensitivity will be examined and compared with the analogues properties of the parent cell bodies in the Edinger Westphal nucleus.
