Final answer:
Amacrine cells can be excited or inhibited by photoreceptors and subsequently modulate the activity of ganglion cells, relaying information from bipolar cells. Horizontal cells contribute by mediating lateral inhibition to enhance image contrast.
Step-by-step explanation:
The cells that can be excited or inhibited by photoreceptors and modify ganglion cells in response to bipolar cells are amacrine cells. Amacrine cells play an essential role in the processing of visual information by distributing information from one bipolar cell to many ganglion cells and contributing to retinal processing before an action potential is produced by retinal ganglion cells.
Horizontal cells also interact with photoreceptors and bipolar cells. They carry signals from one photoreceptor to others and to several bipolar cells, inhibiting more distant photoreceptors and bipolar cells through lateral inhibition, which sharpens edges and enhances contrast. However, amacrine cells are the cells that directly affect ganglion cells after receiving inputs from bipolar cells.