Glia Put Visual Map In Sync

Watching a fireworks display is a breathtaking experience. As explosions pattern the sky, the visual system must capture information about the time-varying positions, colors, and contrasts of myriad spots of light. This testament to high-acuity vision necessitates the development of neural circuits that map visual space. To generate this retinotopy (visual mapping), neurons must differentiate and connect to their synaptic targets with both spatial and temporal precision. How is this achieved? The molecules that regulate neuronal differentiation have been described in detail, as have the cues that allow differentiated neurons to reach and choose their synaptic partners (1, 2). However, the mechanisms that coordinate neuronal specification with the development of retinotopic circuit wiring have remained elusive. On page 886 of this issue, Fernandes et al. (3) demonstrate that in the visual system of flies (Drosophila melanogaster), photoreceptors use glial cells as intermediaries to communicate with their neural targets to generate retinotopic circuits.