Final answer:
Inhibitory postsynaptic potentials (IPSPs) cause the hyperpolarization of the postsynaptic membrane by allowing Cl- ions to enter the neuron, thus making the neuron less likely to fire an action potential.
Step-by-step explanation:
Inhibitory postsynaptic potentials (IPSPs) are essential to neuronal communication and play a critical role in the regulation of neuron firing. When a presynaptic neuron releases the neurotransmitter GABA, it binds to the postsynaptic membrane and opens Cl- channels. This action enables Cl- ions to enter the postsynaptic neuron, leading to hyperpolarization of the membrane.
Hyperpolarization moves the membrane potential further away from the threshold required to trigger an action potential, hence making it less likely that the neuron will fire. Therefore, IPSPs are associated with local hyperpolarizations, which is the correct answer to the question.