A novel interface for cortical columnar neuromodulation with multi-point infrared neural stimulation

Cutting edge advances in electrical visual cortical prosthetics (VCPs) have evoked perception of shapes, motion, and letters in human and nonhuman primates. However, there is no existing method that employs a targeted columnar approach with a non-penetrating array of stimulation points. Neither has there been a direct demonstration that higher order cortical response can be elicited from externally stimulated lower order cortical sites. Here, we take an approach that employs images maps of cortical columns combined with delivery of optical stimulation through a fiber optic array to stimulate selected sets of columns. Specifically, using infrared neural stimulation (INS) delivered through a linear optic fiber array in anesthetized cat visual cortex, we predicted that the orientation of the array would selectively activate different higher order orientation domains in contralateral cat area 18. We found that INS modulation of response to ongoing visual oriented gratings produced enhanced responses in orientation-matched domains and reduced response in non-matched domains, consistent with a known higher order integration mediated by callosal inputs. This establishes proof-of-principle that an external device can access existing cortical circuitry via a column-targeted approach, and provides groundwork for a targeted column-based approach to cortical prosthetics using dense optical fiber bundle arrays.