| Popis: |
Two major functions performed by the retina are to establish the parallel processing of visual information and to adapt visual encoding to the trillion-fold range of light intensities encountered in the environment. Previous work has highlighted many specialized cell types and circuits that instantiate parallel processing and light adaptation. However, fully understanding either process requires identifying how light adaptation and parallel processing interact. One possibility is that light adaptation causes uniform or proportional scaling to the receptive fields (RFs) of different retinal ganglion cell (RGC) types, the output neurons of the retina. Alternatively, light adaptation could cause a reorganization of RF structures across RGC types. A third possibility is that RFs across different RGC types are more similar under some conditions (e.g., low light levels) and more divergent under other conditions. To resolve these possibilities, we examined how the spatiotemporal RF structure of six simultaneously measured RGC types in the rat retina change from rod-to cone-mediated light levels. While light adaptation altered the RF properties of all six RGC types, we found that the relative structure across different RGC types was largely preserved across light levels. However, in both the spatial and temporal domains, one of the six RGC types exhibited adaptation distinct from the other types, resulting in a partial reorganization of RF properties across RGC types. These measurements identify how parallel visual processing interacts with light adaptation and highlights the challenges to stably encode visual scenes across light levels. |
