Which of the following statements about postsynaptic potentials is true?

• A. Postsynaptic potentials are only found in the peripheral nervous system.
• B. Postsynaptic potentials are changes in membrane potential that occur exclusively at the axon hillock.
• C. Postsynaptic potentials can be either excitatory or inhibitory depending on the type of neurotransmitter released.
• D. Postsynaptic potentials always result in the generation of an action potential.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand what postsynaptic potentials (PSPs) are. PSPs are changes in the membrane potential of the postsynaptic neuron caused by neurotransmitters binding to receptors after a synapse.
2. Step 2: Recognize that PSPs can be either excitatory or inhibitory. Excitatory postsynaptic potentials (EPSPs) depolarize the membrane, making the neuron more likely to fire an action potential, while inhibitory postsynaptic potentials (IPSPs) hyperpolarize the membrane, making firing less likely.
3. Step 3: Note that PSPs occur at the postsynaptic membrane, which can be on dendrites or the cell body, not exclusively at the axon hillock. The axon hillock is where action potentials are typically initiated if the threshold is reached.
4. Step 4: Understand that PSPs are found throughout the nervous system, both in the central and peripheral nervous systems, not limited to one area.
5. Step 5: Realize that PSPs do not always lead to an action potential; whether an action potential occurs depends on the summation of all excitatory and inhibitory inputs reaching the axon hillock.