Mechanisms controlling retinal responses to natural stimuli

Summary and expected impact The proposed experiments will provide a clearer picture of the mechanisms that shape responses to natural stimuli in the primate retina. Preliminary results suggest several important insights. Aim 1: We find that standard models fail to account for responses of On parasol cells to natural images. These are among the best-studied ganglion cells, and the inability of standard models to account for their responses is surprising. Specifically, our results suggest that the manner in which these cells integrate signals across space is highly stimulus-dependent in a manner not captured by current models. Aim 2: We find that receptive field subunits - long associated with bipolar cells - have more diverse properties than previously appreciated, likely reflecting contributions of cells other than bipolar cells. In particular, light-dependent changes in subunit size will be important to consider in evaluating the functional role of subunits. Aim 3: A tool that we recently developed reveals significant contributions of post-photoreceptor mechanisms to the kinetics of retinal ganglion cell responses.