Clinical insights into basic visual processes
Time/Room: Friday, May 18, 2018, 12:00 – 2:00 pm, Talk Room 1
Organizer(s): Paul Gamlin, University of Alabama at Birmingham; Ann E. Elsner, Indiana University; Ronald Gregg, University of Louisville
Presenters: Geunyoung Yoon, Artur Cideciyan, Ione Fine, MiYoung Kwon
This year’s biennial ARVO at VSS symposium features insights into human visual processing at the retinal and cortical level arising from clinical and translational research. The speakers will present recent work based on a wide range of state-of-the art techniques including adaptive optics, brain and retinal imaging, psychophysics and gene therapy.
Neural mechanisms of long-term adaptation to the eye’s habitual aberration
Speaker: Geunyoung Yoon, Flaum Eye Institute, Center for Visual Science, The Institute of Optics, University of Rochester
Understanding the limits of human vision requires fundamental insights into both optical and neural factors in vision. Although the eye’s optics are far from perfect, contributions of the optical factors to neural processing are largely underappreciated. Specifically, how neural processing of images formed on the retina is altered by the long-term visual experience with habitual optical blur has remained unexplored. With technological advances in an adaptive optics vision simulator, it is now possible to manipulate ocular optics precisely. I will highlight our recent investigations on underlying mechanisms of long-term neural adaptation to the optics of the eye and its impact on spatial vision in the normally developed adult visual system.
Human Melanopic Circuit in Isolation from Photoreceptor Input: Light Sensitivity and Temporal Profile
Speaker: Artur Cideciyan, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania
Leber congenital amaurosis refers to a group of severe early-onset inherited retinopathies. There are more than 20 causative genes with varied pathophysiological mechanisms resulting in vision loss at the level of the photoreceptors. Some eyes retain near normal photoreceptor and inner retinal structure despite the severe retina-wide loss of photoreceptor function. High luminance stimuli allow recording of pupillary responses driven directly by melanopsin-expressing intrinsically photosensitive retinal ganglion cells. Analyses of these pupillary responses help clarify the fidelity of transmission of light signals from the retina to the brain for patients with no light perception undergoing early phase clinical treatment trials. In addition, these responses serve to define the sensitivity and temporal profile of the human melanopic circuit in isolation from photoreceptor input.
Vision in the blind
Speaker: Ione Fine, Department of Psychology, University of Washington
Individuals who are blind early in life show cross-modal plasticity – responses to auditory and tactile stimuli within regions of occipital cortex that are purely visual in the normally sighted. If vision is restored later in life, as occurs in a small number of sight recovery individuals, this cross-modal plasticity persists, even while some visual responsiveness is regained. Here I describe the relationship between cross-modal responses and persisting residual vision. Our results suggest the intriguing possibility that the dramatic changes in function that are observed as a result of early blindness are implemented in the absence of major changes in neuroanatomy at either the micro or macro scale: analogous to reformatting a Windows computer to Linux.
Impact of retinal ganglion cell loss on human pattern recognition
Speaker: MiYoung Kwon, Department of Ophthalmology, University of Alabama at Birmingham
The processing of human pattern detection and recognition requires integrating visual information across space. In the human visual system, the retinal ganglion cells (RGCs) are the output neurons of the retina, and human pattern recognition is built from the neural representation of the RGCs. Here I will present our recent work demonstrating how a loss of RGCs due to either normal aging or pathological conditions such as glaucoma undermines pattern recognition and alters spatial integration properties. I will further highlight the role of the RGCs in determining the spatial extent over which visual inputs are combined. Our findings suggest that understanding the structural and functional integrity of RGCs would help not only better characterize visual deficits associated eye disorders, but also understand the front-end sensory requirements for human pattern recognition.