The functional role of intracellular calcium signaling in retinal amacrine cells, particularly with respect to computation of visual stimuli

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The retina is a sophisticated image processor that filters, extracts and encodes features from the observed scene and forwards this information to the visual areas of the brain. High spatial resolution and fast encoding necessitates parallel processing by compact retinal circuitries. An effective way to concentrate computing power in neural substrate is dendritic processing ¿ the ability of a neuron to process inputs locally in its dendrites. Amacrine cells ¿ the largest class of retinal interneurons ¿ make use of dendritic processing: most of them are axon-less, using their neurites for receiving and providing synaptic input and output. A prominent example is the starburst amacrine cell, which is necessary for detecting the direction of image motion. Its dendritic branches act largely independently and generate motion direction-dependent signals. The underlying dendrite-autonomous mechanism relies on voltage-gated channels ¿ likely on calcium channels ¿ and may, in addition, involve intracellular Ca2+ stores. Using two-photon Ca2+ imaging, pharmacology and viral gene-transfer the primary goal of this project is to determine the functional role of intracellular Ca2+ signaling for the detection of spatio-temporal input patterns in starburstamacrine dendrites.