The mechanisms underlying cortical motion selectivity

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DESCRIPTION (provided by applicant): One strategy the brain uses to process information rapidly is the use of multiple parallel pathways to analyze different aspects of the world simultaneously. The analysis of a visual scene is thought to be segregated into three parallel pathways dedicated to the processing of color, shape, and motion. During this fellowship we will study the neuronal mechanisms that underlie the third pathway, motion selectivity, in visual cortex. Motion processing in V1 requires cortical neurons that respond selectively to the direction and speed of moving objects in the world. Direction selectivity is a neuronal response property that is created de novo in V1 neurons: it is not present in the neurons of the lateral geniculate nucleus (LGN) that provide visual input to the cortex. Unlike other purely spatial response properties such as orientation selectivity, direction selectivity requires processing in the time domain as well as the space domain: direction selective neurons must discern not only where an object is, but where it was in the previous moment. Direction selectivity is therefore thought to be created by combining inputs from LGN neurons with different receptive field positions and different temporal delays. We will investigate how the signals from the LGN are transformed and combined to give neurons in V1 their directionally selective responses. By studying and understanding direction selectivity, we will learn the rules of information processing that may apply generally to cortical processing of temporal information.