Neuronal mechanisms of image processing in the early visual pathway

State College Of Optometry, New York NY

Investigators

Linked publications, trials & patents

Abstract

PROJECT SUMMARY Images captured by our eyes are processed in the retina by separate ON and OFF pathways that signal light and dark stimuli in visual scenes. The traditional thinking is that the two pathways converge in visual cortex and their responses blend with eye movements, making it difficult to separate ON and OFF pathway function. Our recent work and preliminary results challenge this traditional view by demonstrating that ON and OFF pathways remain segregated in visual cortex, are differently modulated by the luminance contrast and spatiotemporal properties of stimuli, and their function can be measured in the clinic from visual responses to the onset of light and dark stimuli. Our recent work and preliminary results also indicate that the different stimulus preferences from ON and OFF pathways are needed to sample the diverse light and dark stimuli in our visual world, but they also make ON pathways more vulnerable than OFF pathways to low light and scenes that lack bright surfaces. Low light and lack of outdoor vision are also major risk factors in myopia, a visual disorder that blurs vision at far distance and is increasing at an alarming rate across the world. Based on our previous work and preliminary results, we hypothesize that myopia emerges from an under-stimulation of ON visual pathways. In this proposal, we will test this hypothesis by directly measuring the neuronal and visual function mediated by ON and OFF pathways in humans with myopia and normal vision. In the first aim, we will take advantage of standard recording methods already available in the clinic (electroretinography and electroencephalography) to measure the difference in the stimulus tuning of ON and OFF pathways in humans. We will record neuronal signals dominated by retinal interneurons (electroretinography) or retinothalamic pathways (electroencephalography) and investigate how the human ON/OFF neuronal response balance changes with stimulus conditions. We will also use automated photography to measure ON/OFF stimulation balance in outdoor visual scenes, which are thought to protect against myopia progression. In the second aim, we will use new visual tests that we are developing with head-mounted visual displays, wearable eye tracking, and electrically tunable lenses to measure differences in human vision mediated by ON and OFF pathways. We will then and use these data to develop a computational model that simulates myopia progression in different visual environments.