Figure 10.

Retinal circuit involved in generating spontaneous activity in rd1 retina. ON cone bipolar cells (ON CBCs) and electrically coupled AII amacrine cells (AII ACs) are intrinsically oscillatory (insensitive to synaptic blockers). ON cone bipolar cells excite both ON ganglion cells (ON GC; which use AMPA/KA and NMDA receptors) and inhibitory amacrine cells (AC; which use AMPA/KA receptors). ACs in turn provides reciprocal feedback inhibition to ON CBCs as well as feedforward inhibition to ON GCs (mediated by GABA/glycine receptors). Based on comparison with wt retinal circuitry, this model has been extended to the OFF system. It is hypothesized that AIIs amacrine cells drive the OFF bipolar and ganglion cells through disinhibitory mechanisms. Thus, oscillatory drive to amacrine and ganglion cells arises from intrinsic activity in the AII amacrine/ON cone bipolar cell network and is strongly influenced by inhibitory amacrine cells.