Synaptic signaling in the retina

The research proposed here studies the roles of membrane ion channels at the first synapse in the visual system, the photoreceptor synapse. Synapses, the essential connection sites that link neurons together, are also sites at which some pathological conditions take their toll and sites that pharmacological agents exploit in providing therapeutic interventions. Recently, a form of night blindness has been shown to result from altered neurotransmission in the retina, specifically at the photoreceptor output synapse. Projects in the proposal will focus on the response properties of the presynaptic neurons and, especially, how these properties may be changed or modulated by external influences. We hope to quantitatively link presynaptic mechanisms with measurements of the visual signal as it passes this first point of synaptic transfer in the nervous system. We expect to describe and define mechanisms of calcium ion influx at the presynaptic transmitter release site of vertebrate photoreceptors. Via several types of calcium channels, retinal neuromodulators influence the amount of calcium in the cell on a moment-by-moment basis which in turn controls synaptic release.