A dual adaptive optics instrument for testing the role of retinal ganglion cells in vision

Abstract

Retinal ganglion cells (RGCs) are the layer of neurons in the retina that output directly to the brain. In primates, there are approximately 20 distinct types which each transmit an independent encoding of the external visual world in parallel to the brain. 1 The wide variety of RGC types suggests that the retina undertakes a sophisticated set of computations that our used by higher brain areas to decode the visual world. Yet, little is known about the majority of the different types of RGCs present in the primate retina largely due to the rarity of many of them. Current understanding of RGCs largely derives from ex vivo electrophysiology experiments which are acute and require severing the optic nerve. 2 This preparation removes the opportunity to study vision as an intact system and puts a time limit on how long a sample is viable for study before the tissue dies. Traditional electrophysiology also struggles to study the RGCs that serve the fragile fovea, the central high-resolution region of the retina. Adaptive optics (AO) ophthalmoscopy coupled with functional imaging and optogenetics provides a unique set of tools which allows the study of individual RGCs in situ. 3,4 Here we describe a plan for a novel split field of view AO ophthalmoscope that will deliver visual stimuli precisely controlled in space, time, and color to the receptive fields of specific RGCs, while also simultaneously optically recording functional calcium responses from the same RGCs. The device also enables psychophysical experiments to study the perceptual impact of RGC types via optogenetics.