What type of signal do OFF-center bipolar cells respond to in the dark?

OFF-center bipolar cells respond to light in a way that reflects the surrounding light intensity, particularly in the dark. In this state, the photoreceptors (rods and cones) are depolarized due to the absence of light, leading to the release of the neurotransmitter glutamate. OFF-center bipolar cells have ionotropic glutamate receptors that are activated by this glutamate release. When the glutamate binds to these receptors, it results in a depolarization of the OFF-center bipolar cells, generating graded potentials.

Graded potentials are important because they allow for a range of responses based on the amount of light that is perceived by the photoreceptors. In the dark, as glutamate is released from the depolarized photoreceptors, this leads to a sustained depolarization in the OFF-center bipolar cells, which is perceived as increased signaling to the subsequent retinal ganglion cells.

Action potentials, on the other hand, are typically seen in neurons that fire in an all-or-nothing manner, such as ganglion cells. While ganglion cells ultimately transmit signals as action potentials, the OFF-center bipolar cells primarily generate graded potentials.

Thus, the response of OFF-center bipolar cells in the dark aligns with the properties of graded potentials, confirming