Which of the following best describes presynaptic inhibition at a synapse?

• A. The reuptake of neurotransmitter into the presynaptic terminal after synaptic transmission.
• B. The binding of neurotransmitter to postsynaptic receptors, causing depolarization.
• C. An increase in neurotransmitter release from the presynaptic neuron due to the action of a facilitating neuron.
• D. A decrease in neurotransmitter release from the presynaptic neuron due to the action of an inhibitory neuron.

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of presynaptic inhibition. Presynaptic inhibition occurs when the activity of an inhibitory neuron reduces the release of neurotransmitter from the presynaptic neuron, thereby decreasing the signal sent to the postsynaptic neuron.
2. Step 2: Analyze the options provided in the problem. Each option describes a different mechanism or process related to synaptic transmission. Focus on identifying the one that matches the definition of presynaptic inhibition.
3. Step 3: Eliminate incorrect options. For example, 'The reuptake of neurotransmitter into the presynaptic terminal after synaptic transmission' describes a process of neurotransmitter recycling, not inhibition. Similarly, 'The binding of neurotransmitter to postsynaptic receptors, causing depolarization' refers to postsynaptic activation, not presynaptic inhibition.
4. Step 4: Consider the option 'An increase in neurotransmitter release from the presynaptic neuron due to the action of a facilitating neuron.' This describes facilitation, which is the opposite of inhibition.
5. Step 5: Identify the correct answer: 'A decrease in neurotransmitter release from the presynaptic neuron due to the action of an inhibitory neuron.' This matches the definition of presynaptic inhibition, where the inhibitory neuron reduces neurotransmitter release, thereby modulating synaptic transmission.