The temporal structure of transient ON/OFF ganglion cell responses and its relation to intra-retinal processing |
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Authors: | Andreas Thiel Martin Greschner Josef Ammermüller |
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Institution: | (1) Neurobiology, Carl von Ossietzky University Oldenburg, PO Box 2503, D-26111 Oldenburg, Germany |
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Abstract: | A subpopulation of transient ON/OFF ganglion cells in the turtle retina transmits changes in stimulus intensity as series
of distinct spike events. The temporal structure of these event sequences depends systematically on the stimulus and thus
carries information about the preceding intensity change. To study the spike events' intra-retinal origins, we performed extracellular
ganglion cell recordings and simultaneous intracellular recordings from horizontal and amacrine cells. Based on these data,
we developed a computational retina model, reproducing spike event patterns with realistic intensity dependence under various
experimental conditions. The model's main features are negative feedback from sustained amacrine onto bipolar cells, and a
two-step cascade of ganglion cell suppression via a slow and a fast transient amacrine cell. Pharmacologically blocking glycinergic
transmission results in disappearance of the spike event sequence, an effect predicted by the model if a single connection,
namely suppression of the fast by the slow transient amacrine cell, is weakened. We suggest that the slow transient amacrine
cell is glycinergic, whereas the other types release GABA. Thus, the interplay of amacrine cell mediated inhibition is likely
to induce distinct temporal structure in ganglion cell responses, forming the basis for a temporal code.
Action Editor: Jonathan D. Victor |
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Keywords: | Retinal circuitry Temporal coding Amacrine cells Glycine Reciprocal feedback Concatenated inhibition Computational model |
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