The layers of the retina (PE: pigment epithelium, PR: visual receptors, ONL: outer nuclear layer, OPL: outer plexiform layer, INL: internal nuclear layer, IPL: internal plexiform layer, GC: ganglion cell layer, and SO: Stratum opticum). Dopamine neurons (TOH+: Tyrosine hydroxylase positive neurons, Type 1 cells and Type 2 amacrine cells) are primarily concentrated in the INL and dopamine positive neurites (Type 1 in stratum 1 and type 2 ramify above stratum 1) in the IPL. Type 1 cells may synapse onto GABA interpelexiform cells (IPCs). Some dopamine activities may also be observed in the ganglion cell layer.
