When light is present, ON-center bipolar cells primarily respond how?

ON-center bipolar cells play a critical role in the processing of visual information in the retina. When light strikes the photoreceptors (rods and cones) that synapse onto ON-center bipolar cells, it initiates a series of biochemical changes that affect the release of neurotransmitters. In the dark, photoreceptors release glutamate, which hyperpolarizes the ON-center bipolar cells. However, when light hits the photoreceptors, it reduces the amount of glutamate released. This reduction in glutamate removes the inhibition on the ON-center bipolar cells, leading to their depolarization.

The depolarization of ON-center bipolar cells results in the increased release of neurotransmitters from these cells onto ganglion cells, which then transmit the signal to the brain. This process allows the visual system to detect light and contribute to the perception of brightness and contrast in the visual field. Thus, the primary response of ON-center bipolar cells to light is depolarization, which is fundamental to their function in retinal signaling.