Which retinal cells participate in horizontal, lateral interactions across neighboring photoreceptors?

• A. Amacrine cells
• B. Ganglion cells
• C. Horizontal cells
• D. Müller glia

Answer: (C)

Horizontal cells are specialized neurons in the outer retina that form a lateral network with neighboring photoreceptors. They receive input directly from photoreceptors in the outer plexiform layer and provide inhibitory feedback back to those photoreceptors, creating a wide, horizontal influence that spans across several neighboring cells. This lateral interaction shapes the photoreceptor signals into center-surround receptive fields, which enhances contrast and helps detect edges. Other retinal cells serve different roles: amacrine cells operate mainly in the inner retina between bipolar and ganglion cells, ganglion cells are the output neurons that send visual information to the brain, and Müller glia provide structural and metabolic support. So the horizontal, cross-photoreceptor interactions are carried out by horizontal cells.