The visual cortex is a main center of the brain for processing visual input. From physiological recordings, it is known that part of this area acts as a "map" of visual space, so that an object in a particular place in the visual world evokes activity in nerve cells (neurons) in a particular place in the visual cortex. It remains unclear just how that neural activity in space and time is related to the perception of an object and its location. This project utilizes further development of a novel multiple-electrode array to investigate how highly local stimuli might mimic normal visual signals. Engineering techniques are developed to interface the array with the brain, and to provide adequate stimulation in a way to test feasibility for a visual prosthesis for the blind. Electrophysiological tests will be done to try to correlate stimulation patterns with thresholds for visual sensation. Results will provide valuable information on how spatially patterned visual stimuli produce visual perceptions of objects in the world. This work will have an impact not only on visual neuroscience, but on clarifying neurobiological principles of coding in the cortex in general, and on the development of bioengineering visual aids for the blind.
