What happens to the membrane potential of ON-center ganglion cells in response to a decrease in illumination?

The membrane potential of ON-center ganglion cells is directly influenced by changes in light levels in their receptive fields. In the dark (or under decreased illumination), photoreceptors in the retina, such as rods and cones, become less hyperpolarized, leading to an increase in the release of the neurotransmitter glutamate.

In the ON-center pathway, the ON-center bipolar cells are depolarized by the increased glutamate levels. This depolarization is due to the fact that ON-center bipolar cells are activated by the presence of glutamate in a way that leads to the closure of certain cation channels (such as the mGluR6 pathway). Therefore, when there's less light leading to increased neurotransmitter release from photoreceptors, the ON-center bipolar cells become less depolarized, and consequently, the ON-center ganglion cells discharge frequency increases.

The overall effect is that the ON-center ganglion cells depolarize in response to decreased illumination, which is contrary to what might be expected based on the word "illumination." Thus, the correct understanding here is that in response to a decrease in illumination, ON-center ganglion cells experience changes in their membrane potential that lead to depolarization from their baseline state due to the