How is hyperpolarization defined in relation to the resting membrane potential?

Hyperpolarization is defined as a change in the membrane potential that makes it more negative than the resting membrane potential. In a typical neuron, the resting membrane potential is around -70 mV; during hyperpolarization, this value can drop to -80 mV or even more negative. This occurs due to the opening of potassium channels or the closing of sodium channels, leading to a greater influx of negative charges or a decrease in positive charges inside the cell.

By making the interior of the cell more negative relative to the outside, hyperpolarization increases the threshold that must be reached for an action potential to occur, making it more challenging for the neuron to fire. This concept is crucial in understanding neuronal excitability and the overall function of action potentials in neural signaling.