Light adaptation in regionally and functionally distinct retinal circuits

The National Eye Institute awarded the University of Wisconsin–Madison $249,672 under the Vision Research program (CFDA 93.867) on May 8, 2026, to support a project grant investigating light adaptation in regionally and functionally distinct retinal circuits.

The project examines how the primate retina modulates neural response gain and kinetics across changing light conditions, with specific focus on foveal versus peripheral regions and on versus off visual pathways. Aim 1 determines the impact of signal convergence on adaptation properties—gain, kinetics, noise, and time course—in foveal and peripheral midget and parasol pathways, and evaluates synaptic inhibition as a mechanism for circuit adaptation to luminance. Aim 2 investigates how cone photoreceptor asymmetries in light increment versus decrement sensitivity shape functional adaptation in peripheral on and off pathways. The work addresses a gap in understanding how foveal circuits maintain contrast perception across varying background luminance, with applications toward prosthetic retinal implants.

Performance occurs in Wisconsin. The period of performance runs through November 30, 2027. This is a Project Grant, a non-renewable assistance type under NEI's Vision Research program that supports investigator-initiated research evaluated on scientific and technical merit, programmatic relevance, and fund availability.

Abstract

Visual tasks, like reading print or recognizing faces, often require detailed spatial information collected under changing lighting conditions. In the retina, as light intensity varies so do the gain and kinetics of neural responses-a process called adaptation that prevents saturation and supports a consistent perception of contrast. A significant GAP in knowledge is how light adaptation functions in the fovea-the central most region of retina responsible for high-acuity vision. Retinal circuit adaptation relies on signal pooling, and therefore adaptation may vary between foveal and peripheral regions that differ in convergence. Additionally, cone photoreceptors in peripheral primate retina are known to be asymmetric in their sensitivity to light increments VS decrements. Therefore, circuit adaptation may differ in on and off visual pathways. The objective of this project is to use distinct primate retinal circuits-foveal VS peripheral and on VS off-to determine how circuits with differing signal to noise ratios modulate gain and kinetics across light conditions. Aim 1 will determine the impact of convergence on properties of retinal circuit adaptation (gain, kinetics, noise, and time course) in the primate foveal VS peripheral midget and parasol pathways, as well as the contribution of synaptic inhibition as a potential mechanism for circuit adaptation to luminance. Aim 2 will determine how asymmetries inherited from cone photoreceptors shape the functional properties of adaptation in the primate on VS off peripheral midget pathway. Given the importance of the fovea for our everyday vision, this work will bridge a GAP in our knowledge of how foveal circuits adapt to changes in contrast over varying background luminance, critical for the function of high-acuity vision. These results will positively impact the pursuit towards prosthetic retinal implants that can recapitulate properties of foveal circuits by providing a template for function in diverse retinal circuits. The training plan described in this proposal is designed to enable me to develop the skills necessary to reach my career goal of an independent investigator. By following this plan with the guidance of my sponsor and CO-sponsor, i will continue to learn new electrophysiology techniques to build a strong foundation in retinal circuit research. I will develop my writing, communication, teaching, mentoring, networking, and scientific outreach skills. This research will take place at the university of wisconsin-madison where the strong intellectual environment and availability of primate tissue from the wisconsin national primate research center will be leveraged.