Final answer:
Synaptic efficacy changes involve EPSPs and IPSPs, which depend on neurotransmitter-receptor interactions leading to depolarization or hyperpolarization of the postsynaptic neuron. Further, synaptic plasticity can result in LTP or LTD, altering the strength of synaptic connections through changes in AMPA receptors.
Step-by-step explanation:
Changes in synaptic efficacy due to changes in depolarization of the postsynaptic neuron involve the processes of Excitatory Postsynaptic Potentials (EPSPs) and Inhibitory Postsynaptic Potentials (IPSPs). An EPSP occurs when neurotransmitters like acetylcholine bind to receptors and cause depolarization of the membrane, making the neuron more likely to fire an action potential. Conversely, when GABA is released, it induces IPSPs, leading to hyperpolarization and making it less likely for the neuron to fire. During Long-term Potentiation (LTP), repeated stimulation of a synapse strengthens it by increasing the number of AMPA receptors in the postsynaptic membrane, thus enhancing the excitatory response. In contrast, reduced stimulation can induce Long-term Depression (LTD), wherein AMPA receptors are removed, making the synapse less responsive to neurotransmitters.