Figure 8. Summary of rod, cone and HC synaptic interactions.

Schematic diagram of synaptic interactions among six types photoreceptors: rod (R), rod_C (R_C), large single cone (lC), principal member of a double cone (pC), accessory member of a double cone (aC, grey portion of the double cone), and small single cone (sC), as well as the A- and B-type horizontal cells and B-type HC axon terminals (HC_A, HC_B and HC_B-AT). Zigzags, electrical synapses (thicker lines indicate stronger coupling); green arrows, glutamatergic synapses; large red arrows, HC→cone feedback synapses; small red arrows, possible direct rod→cone chemical synapses.