Researcher shows linkage between ganglion cell density and non-uniform spatial integration in human vision

University of Alabama at BirminghamMiYoung Kwon, Ph.D. researchers have found that the variation in the retinal ganglion cell density across the human retina is closely matched to the variation in the extent of spatial recognition — a discovery that suggests a fixed number of retinal ganglion cells subserves spatial integration of visual input, independent of the visual-field location.

MiYoung Kwon, Ph.D., assistant professor in the Department of Ophthalmology and Visual Sciences, and postdoctoral researcher Rong Liu published their findings in the Proceedings of the National Academy Sciences of the United States of America, one of the top scientific journals in the world.

In order for humans to detect or recognize a target, the visual system has to integrate signals across the visual field — a process called spatial integration. The extent of spatial integration, or the size of the window within which visual information is integrated across visual space, has been observed to depend largely on the position of the target in the visual field. However, the mechanism underlying the variation in the extent of spatial integration across the visual field has been elusive.

In Kwon’s study, researchers examined a relationship between the distribution of retinal ganglion cells, or the output neurons on the retina, and the spatial integration by quantifying the number of ganglion cells underlying the integration zone. The findings showed that the property of human spatial integration can be explained largely by uneven distribution of the retinal ganglion cells and suggested that, regardless of visual field location, a fixed number of ganglion cells is involved in spatial integration of visual input.

“Our findings illuminate the fundamental organizing principle of human visual processing in healthy brains,” Kwon said. “This work may also have important clinical applications for the diagnosis and management of vision that exhibits significant loss of retinal ganglion cells, such as glaucoma or aging vision.”