Hyperpolarization is when a neuron’s membrane potential (mV) becomes more negatively charged (value less than 0) at a specific location on the cell membrane. As a result, the neuron is less likely to fire an action potential.

Image of the process of hyperpolarization.

The permeability of the membrane to ions changes with depolarization (towards 0) or hyperpolarization (away from 0). The typical neuronal resting potential is approximately -90 mV for the extracellular fluid.

Membrane potentialFrom -70 to -90mV
ChargeNegative charge increases
Major CauseOpening of channels that let K+ out of the cel or CI- ions into the cell
Flow of Positive IonsOut of cell
Na+ K+ ionsK+ ions flow out of the cell
Na+ channelsClosed
K+ channelsOpened

Interesting comment in Khan Academy:


Felten, D. L., O’Banion, M. K., & Maida, M. E. (2021). Netter’s Atlas of Neuroscience E-Book. Elsevier Health Sciences.

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