Paul Gamlin, PhDA recent study in Nature Communications describes the origins of direction selectivity in the non-human primate (NHP) retina. "Origins of direction selectivity in the primate retina" was published by a group of international researchers, including Paul Gamlin, PhD, at UAB and led by his long-time collaborator, Dr. Dennis Dacey, at the University of Washington.

Prior investigations of rabbit and mouse retina have reported robust directionally selective retinal circuits impinging on directionally-selective ganglion cells (DSGC), while investigations of NHP retina had previously found scant evidence for such circuits. Nevertheless, building on an enabling technique developed by Drs. Gamlin and Dacey this team combined multiple additional cutting-edge experimental and computational techniques to definitively show that the NHP retina contains comparable directionally selective retinal circuits to those seen in other mammals.

They found exactly the same class of amacrine cell provided presynaptic input to DSGC, but with significant differences in the number of classes of DSGCs. Specifically, in mice, starburst amacrine cells are part of the circuitry that provides directional tuning to four ON-OFF DSGC subtypes with complementary preferred direction preferences aligned with the optic-flow fields generated on the retina by the animal’s motion through the environment. However, in the NHP, starburst amacrine cells are part of the circuitry that provides directional tuning to only a single ON–OFF DSGC type.

Paul Gamlin, Professor and Director of Basic and Translational Research in the Department of Ophthalmology and Visual Sciences says that these findings will lead to a new understanding of how the NHP retina processes visual information. For example, the existence of only one type of ON–OFF DSGC in the NHP retina may not be totally unexpected since primates have forward facing eyes with optic flow centered on the fovea while mice and rabbits have laterally-placed eyes resulting in a very different pattern of optic flow on the retina. This will require further investigations. In addition, these studies will prompt further studies of how these retinal direction-selective pathway interact with other retinal and central direction tuned signals within diverse visual cortical areas. More generally, these studies will lead to a far better understanding of how primate vision uses retinal optic flow and retinal motion information in general for visually-guided navigation and perception.