Retinal ganglion cell maps in the brain: implications for visual processing

- The retina conveys a rich set of information about the content of the visual world to the brain.
- Genetic tools are starting to reveal 'labeled lines' extending from the retina to visual targets in the brain that control specific behaviors.
- The dorsal lateral geniculate nucleus harbors cell types tuned for directional motion and orientation features that may arise from the retina.
- Genetic and imaging studies are starting to provide a window into how retinal maps are kept separate or combined within the brain.

Everything the brain knows about the content of the visual world is built from the spiking activity of retinal ganglion cells (RGCs). As the output neurons of the eye, RGCs include ∼20 different subtypes, each responding best to a specific feature in the visual scene. Here we discuss recent advances in identifying where different RGC subtypes route visual information in the brain, including which targets they connect to and how their organization within those targets influences visual processing. We also highlight examples where causal links have been established between specific RGC subtypes, their maps of central connections and defined aspects of light-mediated behavior and we suggest the use of techniques that stand to extend these sorts of analyses to circuits underlying visual perception.