Depolarization and hyperpolarization occur when ion channels in the membrane open or close, altering the ability of particular types of ions to enter or exit the cell. ... The opening of channels that let positive ions flow out of the cell (or negative ions flow in) can cause hyperpolarization.

What causes hyperpolarization?

Unsourced material may be challenged and removed. Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. ... Hyperpolarization is often caused by efflux of K⁺ (a cation) through K⁺ channels, or influx of Cl^– (an anion) through Cl^– channels.

What could cause hyperpolarization in the postsynaptic cell?

Communication at chemical synapses requires release of neurotransmitters. ... The neurotransmitter diffuses across the synaptic cleft and binds to ligand-gated ion channels in the postsynaptic membrane, resulting in a localized depolarization or hyperpolarization of the postsynaptic neuron.