Though some sensory modalities can be restored through engineered devices, such as cochlear implants for the severely hearing impaired, there are few viable options for restoring vision to the profoundly blind. This project tests whether electrically activating neural cells in the visual system can convey useful visual information. We are testing the effectiveness of electrical microstimulation generated by microelectrode arrays that penetrate into the cerebral cortex, and micro-electrocorticography (micro-ECoG) grids that rest on the surface of the cerebral cortex. Results gained from these experiments will reveal significant new insights into how microstimulation conveys sensory information to the human brain.
Using patient behavioral responses to, and verbal descriptions of, visual perceptions evoked by microstimulation of visual cortex, we will fulfill five main objectives. 1) Determine the optimal parameters of microstimulation for consistently evoking visual perceptions. 2) Learn how spatial and temporal separation of microstimulations effect evoked visual perceptions. 3) Gain the ability to evoke complex visual perceptions using spatiotemporal patterns of microstimulation. 4) Establish whether patients can improve their ability to discriminate between evoked visual perceptions, and if this improvement correlates with changes in patterns of cortical activity. 5) Resolve whether cortical plasticity occurs in response to repeated exposure to patterned microstimulation, and whether this plasticity correlates with improved discrimination between evoked perceptions.
The results of this project will provide increased understanding of the relationship between the spatial and temporal parameters of microstimulation and evoked subjective perceptions. This project focuses on microstimulation of the visual cortex and evoking visual perceptions, but knowledge gained during this project will provide broad guidance on the development of all sensory neural prostheses.