Surround-mediated temporal and spatial filtering by retinal ganglion receptive fields shape the information encoded in the output of the retina.

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Project Abstract Scientists are starting to decode the languages of neural circuits and are finding that the limits of perception are defined by the circuits that detect, process, and relay stimuli information. In vision, understanding the how a stimulus is represented at the output of the retina and how that representation changes with light conditions is key to defining the information content passed to the cortex. Retinal ganglion cells (RGCs) are responsible for performing the last circuit computations in the retina and generating and relaying light information to the cortex. A defining feature of RGC sensitivity is a receptive field with center-surround antagonism. These types of circuits are mediated by lateral inhibition so that stimuli detected in the surround modulate those detected in the center. Since the original discovery of center-surround antagonism in the retina, it has been shown in multiple model species that surround interactions are light dependent. While studies have begun to reveal the circuit mechanisms responsible for the light dependence of receptive fields, we still lack a complete understanding of how spatial and temporal features of receptive fields change with light conditions. I propose to study how light controls the spatial- and temporal-filtering mediated by the receptive field surround and how that shapes the final output of primate retina. In Aim1 I will measure the light dependence of the surround-mediated filtering and determine the functional detections limits at the level of retinal output. Aim2 will identify how circuit routing determines access to inner and outer sources of lateral inhibition and other light dependent mechanisms adjusting the strength of surround modulations in the spatial and temporal domains. Fully understanding the dynamic properties of surround-mediating filtering in primate retina not only adds to our understanding of how lateral inhibition affects sensory encoding and detection, but importantly, will also provide new insights into how retinal circuits define the limits of human perception.