Question

How can Glutamate depolarize or hyperpolarize bipolar cells?

Answer 1

The functioning of bipolar cells depends on two mechanisms. First, the continuous release of glutamate from photoreceptors in the dark depolarizes some bipolar cells and hyperpolarizes other cells, depending on whether the cells have excitatory or inhibitory glutamate receptors. Second, light causes photoreceptors to be hyperpolarized, thereby reducing glutamate release.

Glutamate binds to specific receptor present on the bipolar cells, these receptors are associated with types of ion channels. Depending on the kinds of ion channels present, the bipolar cell may become depolarized (as do most neurons when glutamate is released), or it may become hyperpolarized.