Final answer:
Inhibitory cell hyperpolarization occurs when the membrane potential becomes more negative, making it less likely to fire an action potential.
Step-by-step explanation:
Inhibitory cell hyperpolarization occurs when the membrane potential of the cell becomes more negative, making it less likely to fire an action potential. This can be caused by the release of inhibitory neurotransmitters such as GABA, which opens Cl- channels and allows Cl- ions to enter the cell, hyperpolarizing the membrane.