In neuroscience, repolarization refers to the change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential has just previously changed the membrane potential to a positive value; the repolarization phase usually returns the membrane potential back to the resting membrane potential. Repolarization results from the movement of positively charged potassium ions out of the cell. Typically the repolarization phase of an action potential results in hyperpolarization, attainment of a membrane potential that is more negative than the resting potential.