Many cells in the cortex of the brain respond best to highly specific stimuli, and the neural mechanisms that "tune" the cell's response remain largely unclear. For a given cell in the visual cortex, it is possible to define its "receptive field" as the area in visual space in which an appropriate visual stimulus (for example a light bar, or a moving edge, or even a complex shape) causes a recordable response in the cell. There may be a particular combination of both spatial and temporal features of that stimulus that elicit the "best" response from the cell. This project will examine the relations between receptive field structure and responses to slowly moving visual gratings (series of light and dark bars). Repetitive presentations of such drifting gratings in one direction cause adaptation in the cell, so its response decreases to the movement in one direction, but not to movement in the other. Single cell activity will be recorded to map out the receptive field to a single bar stimulus before, during, and after the selective adaptation to the grating, to see how the receptive field changes. A mathematical model will be used to describe both response strength and timing across the receptive field. The results will be interpreted in terms of neural inputs to the cortical cells, with an emphasis on how the spatial and temporal components contribute to the timing of cortical responses. These studies provide a novel approach to the important question of how visual cortical response properties are generated from convergence of different types of inputs, and will have an impact across sensory neuroscience and computational neuroscience.
