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Mon, Nov 21

Speaker: Chethan Pandaranith, Ph.D.

Title: The adjustment of temporal processing in the retina: mechanisms and functional significance

Abstract:  The ability to adapt to changing conditions is critical to the functioning of any sensory system. The vertebrate visual system, for example, is well-known for its flexibility - as an animal moves between different environments, the visual system adjusts its processing to match the changing conditions (e.g. changes in luminance, contrast, etc). Though these adjustments have been recognized for years, the mechanisms that underlie them have been unclear. Here I'll describe a case in which the mechanism could be determined. We investigated a well-known adjustment - the adjustment in temporal processing that accompanies the shift from day to night vision. Our findings revealed a novel mechanism in the retina that underlies this adjustment, which may generalize to other networks as well. Further, characterizing this adjustment led to the discovery of a previously unknown divergence in the retina's parallel pathways. I'll describe this divergence, and its functional role in natural vision. Finally, I'll also discuss more recent work in the lab, which builds on our knowledge of the retina's processing to develop a high-performance neural prosthetic for vision restoration. The approach combines optogenetic stimulation with algorithms that mimic retinal coding, allowing degenerated retinas to produce normal or near-normal visual signals to be sent to the brain. I'll give an overview of the approach, and describe some of the technology we've developed for stimulating retinal neurons with high spatial and temporal precision.

Host: Dr. Hargrove