Final answer:
In the retina, exposure to light hyperpolarizes photoreceptors, decreasing their release of glutamate. This, in turn, leads to the depolarization of off bipolar cells that are normally inhibited by glutamate, causing an increase in voltage.
Step-by-step explanation:
Photoreceptors are hyperpolarized by light and release less glutamate. Off bipolar cells are inhibited by glutamate, receiving input from photoreceptors. Therefore, in the absence of glutamate, they are depolarized and exhibit an increase in voltage.
Photoreceptors and bipolar cells undergoing hyperpolarization is a unique response compared to other sensory receptors, which typically become depolarized upon stimulus. In the retina, light causes photoreceptors to hyperpolarize, reducing the release of glutamate and disinhibiting the bipolar cells, resulting in their activation.