Milestones and mechanisms for generating specific synaptic connections between the eyes and the brain

All information about the visual world is conveyed to the brain by a single type of neurons at the back of the eye called retinal ganglion cells (RGCs). Understanding how RGC axons locate and wire up with their targets is therefore critical to understanding visual development. In recent years, several important technological and conceptual advances have been made in this area, and yet, many fundamental questions remain unanswered. Indeed, while much is now known about how RGC axons pathfind at the optic chiasm and form retinotopic maps within their targets, how RGCs select their overall targets in the first place is poorly understood. Moreover, the signals that direct mammalian RGC axons to their appropriate layer within those targets remain unknown. The recent advent of genetic tools to selectively label and manipulate defined groups of RGCs is starting to provide a way to resolve these and other important questions about RGC wiring specificity. This field is therefore positioned to reveal new principles of visual circuit development that no doubt will extend to other regions of the CNS.