Project Summary/Abstract The goal of this proposal is to develop a high-fidelity adaptive electrical interface to the retina and use it to investigate the contributions of the parallel visual pathways (M and P, ON and OFF) to the perception and behavior of macaque monkeys. The device will operate bi-directionally at the resolution of single cells and single spikes, and will adapt itself to the diversity of cell types and locations in the host neural circuitry. We build on our extensive work in isolated primate retina, which demonstrates the ability to electrically stimulate and record nearly complete populations of retinal ganglion cells at single-cell, single-spike resolution. We will develop the technologies needed to take this approach to the in vivo setting, and then use them to probe visual function in behaving macaques, by pursuing three aims: (1) develop and test a high-density, large-scale electrical recording and stimulation device, (2) develop surgical techniques, test biocompatibility, and test functionality in anesthetized animals, and (3) probe the computations within and between the M and P pathways and their role in motion vision. Our unique approach to these problems relies on a team with extensive experience in neurophysiology, visual behavior, integrated circuits, materials science, surgery, and signal processing. In addition to testing fundamental aspects of visual function in novel ways, this work will produce a platform technology for other neural interfaces and a functional prototype for a future retinal implant to treat incurable blindness.