Which two retinal interneuron types mediate lateral inhibition?

Which two retinal interneuron types mediate lateral inhibition?

• A. Amacrine cells and bipolar cells
• B. Horizontal cells and amacrine cells
• C. Bipolar cells and photoreceptors
• D. Ganglion cells and amacrine cells

Answer: (B)

Lateral inhibition in the retina is produced by inhibitory interneurons that sculpt how a cell’s receptive field responds to light. In the outer retina, horizontal cells connect across the photoreceptors and to the dendrites of bipolar cells. When light activates a region, horizontal cells provide inhibitory feedback that dampens the activity of neighboring photoreceptors and feeds forward to bipolar cells, creating a surround that suppresses the response in adjacent areas. This surround inhibition is what sharpens edges and enhances contrast at the level of the early visual signal. In the inner retina, amacrine cells operate in the network between bipolar cells and ganglion cells. They release inhibitory neurotransmitters onto neighboring pathways, further refining the signals that reach the ganglion cells and contributing to the temporal and spatial shaping of the visual information. Together, these two interneuron types establish the center-surround organization that underlies contrast enhancement in vision. Other options don’t fit as well because photoreceptors and bipolar cells primarily transmit signals rather than provide lateral inhibition, and ganglion cells are the output neurons rather than interneurons mediating the lateral interactions. The combination of horizontal cells in the outer retina and amacrine cells in the inner retina is what mediates lateral inhibition across the retina.

Lateral inhibition in the retina is produced by inhibitory interneurons that sculpt how a cell’s receptive field responds to light. In the outer retina, horizontal cells connect across the photoreceptors and to the dendrites of bipolar cells. When light activates a region, horizontal cells provide inhibitory feedback that dampens the activity of neighboring photoreceptors and feeds forward to bipolar cells, creating a surround that suppresses the response in adjacent areas. This surround inhibition is what sharpens edges and enhances contrast at the level of the early visual signal.

In the inner retina, amacrine cells operate in the network between bipolar cells and ganglion cells. They release inhibitory neurotransmitters onto neighboring pathways, further refining the signals that reach the ganglion cells and contributing to the temporal and spatial shaping of the visual information. Together, these two interneuron types establish the center-surround organization that underlies contrast enhancement in vision.

Other options don’t fit as well because photoreceptors and bipolar cells primarily transmit signals rather than provide lateral inhibition, and ganglion cells are the output neurons rather than interneurons mediating the lateral interactions. The combination of horizontal cells in the outer retina and amacrine cells in the inner retina is what mediates lateral inhibition across the retina.