An Amacrine Cell Circuit for Signaling Steady Illumination in the Retina

•CRH-1 amacrine cells provide GABAergic inhibition to Suppressed-by-Contrast RGCs•Ablation of CRH-1 cells disrupts suppression to positive contrasts in the SbC RGC•We define an amacrine to RGC circuit and show its functional role

SummaryDecades of research have focused on the circuit connectivity between retinal neurons, but only a handful of amacrine cells have been described functionally and placed in the context of a specific retinal circuit. Here, we identify a circuit where inhibition from a specific amacrine cell plays a vital role in shaping the feature selectivity of a postsynaptic ganglion cell. We record from transgenically labeled CRH-1 amacrine cells and identify a postsynaptic target for CRH-1 amacrine cell inhibition in an atypical retinal ganglion cell (RGC) in mouse retina, the Suppressed-by-Contrast (SbC) RGC. Unlike other RGC types, SbC RGCs spike tonically in steady illumination and are suppressed by both increases and decreases in illumination. Inhibition from GABAergic CRH-1 amacrine cells shapes this unique contrast response profile to positive contrast. We show the existence and impact of this circuit, with both paired recordings and cell-type-specific ablation.

Graphical AbstractFigure optionsDownload full-size imageDownload as PowerPoint slide