Under photopic conditions, two 5-quanta flashes cause how many ganglion cells to reach threshold?

Under photopic conditions, two 5-quanta flashes cause how many ganglion cells to reach threshold?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (B)

Under photopic vision, cones provide high-acuity, low-convergence signaling. Each cone’s input is carried forward through pathways that preserve spatial detail, so there is nearly a one-to-one relationship between active cones and the ganglion cells that respond to them, especially in the central retina. A 5-quanta flash is sufficient to activate a cone, and that cone’s signal can drive its corresponding ganglion cell to threshold. If two flashes illuminate two separate cones, two distinct cone-to-ganglion-cell pathways reach threshold, producing two active ganglion cells. So, the number of ganglion cells reaching threshold matches the number of distinct cones activated by the flashes—two in this case.

Under photopic vision, cones provide high-acuity, low-convergence signaling. Each cone’s input is carried forward through pathways that preserve spatial detail, so there is nearly a one-to-one relationship between active cones and the ganglion cells that respond to them, especially in the central retina.

A 5-quanta flash is sufficient to activate a cone, and that cone’s signal can drive its corresponding ganglion cell to threshold. If two flashes illuminate two separate cones, two distinct cone-to-ganglion-cell pathways reach threshold, producing two active ganglion cells.

So, the number of ganglion cells reaching threshold matches the number of distinct cones activated by the flashes—two in this case.