Ethanol neurotoxicity affects neurotransmitter release. Experiments will be carried to test the hypothesis that ethanol exposure results in structural and biochemical changes in presynaptic terminals. First, a transgenic mouse that expresses yellow fluorescent protein (YFP) in a subset of cerebellar mossy fiber terminals will be used to determine whether ethanol treatment affects the size of the mossy fiber terminals. Second, the effect of ethanol on presynaptic protein SNAP-25 will be determined. These experiments will provide novel insights on how ethanol affects cerebellar circuitry at presynaptic terminals.