VIP+ amacrine cells synchronize neural activity in the retina

In early sensory circuits, inhibitory interneurons are best known for mediating lateral inhibition, gain control, and feature selectivity, but their roles at the population level are less understood. Using two photon digital holography, we found that in the retina, vasoactive intestinal peptide expressing (VIP+) amacrine cells not only inhibit some retinal ganglion cell types via GABAergic synapses but also excite specific other types through gap junctions. Selective knockout of these junctions abolished synchronized firing among these ganglion cells, showing that VIP+ amacrine cells coordinate their activity. Thus, VIP+ interneurons have a dual, cell type specific role: synchronizing some ganglion cells electrically while inhibiting others chemically, thereby differentially shaping retinal output.