Retinal ganglion cell maps in the brain imlications for visual processing

Retinal ganglion cell maps in the brain: implications for visual processing. By O.S. DHANDE, and A.D. HUBERMAN, 1Department of Neurosciences, University of California, San Diego,United States, 2Neurobiology Section in the Division of Biological Sciences, University of California, San Diego, United States, and 3Department of Ophthalmology, University of California, San Diego, United States
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The retinal ganglion cells (RGCs) function as the output neurons of the eye providing signals to the brain for visual processing and has about 20 different subtypes. The intrinsically photosensitive RGCs include 5 subtypes, each projecting around two central targets namely the supra-chiasmatic nucleus (SCN), associated with circadian clock and the olivary pretectal nucleus (OPN) dealing with pupillary behaviors. The subtypes are associated with mood changes, possible role in migraine headache and developmental roles such as avoidance of bright light by neonates, retinal vasculature assembly and early retinal patterning. The superior colliculus receives input from the retina and transgenic studies in mice have shown four maps of RGC input with each SC neuron receiving input from approximately 6 RGCs. The neurons are sensitive to directional and local object movement. A recent study on the integration of laminar maps of RGC axons and their response targets in the tectum of zebrafish revealed that specific populations of RGCs send visual information to restricted regions within the tectum and instructed the tuning of target neurons. Two broad categories of distinct retinal maps: direction selective RGC (DSGC) and non-DSGC exist in mouse lateral geniculate nucleus and each of which receive input from 1 to 3 subtypes of RGCs. A class of On-DSGC provides target specific signals to two distinct regions of the brainstem. Thus RGCs converge to provide retinal inputs to specific brain regions and further understanding of this convergence will provide a better understanding of the role of RGCs in visual behavior.
Dhande OS &amp. Huberman AD (2014). Retinal ganglion cell maps in the brain: implications for visual processing. Current Opinion in Neurobiology, 24, pp.133-142.