Which retinal layer houses the synapses between bipolar cells and ganglion/amacrine cells?

• A. Inner Plexiform Layer
• B. Outer Plexiform Layer
• C. Inner Nuclear Layer
• D. Ganglion Cell Layer

Answer: (A)

In the retina, the connection between bipolar cells and ganglion/amacrine cells happens in the inner plexiform layer. This layer sits higher up in the inner retina and is where the signal from bipolar cells is transmitted to the neurons that send information toward the brain (ganglion cells and amacrine cells). The outer plexiform layer, by contrast, is where photoreceptors connect to bipolar and horizontal cells, while the inner nuclear layer contains the cell bodies of bipolar, amacrine, and horizontal cells, and the ganglion cell layer contains the bodies of ganglion cells. The inner plexiform layer is also organized into sublaminae that help separate ON and OFF pathways, guiding how signals are relayed onward.