Figure 2. ipRGCs possess receptors for glutamate, GABA, and glycine.

Responses of an ipRGC to exogenously applied neurotransmitter agonists. Synaptic transmission was blocked by extracellular cobalt. Ramp responses illustrate voltage dependence of baseline-subtracted currents evoked by puffed l-glutamate (2 mm, co-applied with 5 μm glycine as the co-agonist for NMDA receptors), GABA (1 mm), and glycine (1 mm).