What is the role of an excitatory neurotransmitter?

The role of an excitatory neurotransmitter is to increase the likelihood of an action potential occurring in the postsynaptic neuron. When an excitatory neurotransmitter, such as glutamate, binds to its receptors on the postsynaptic membrane, it typically leads to depolarization of the neuron. This means that the inside of the neuron becomes more positively charged relative to the outside, which can push the membrane potential closer to the threshold needed to trigger an action potential. By facilitating this process, excitatory neurotransmitters play a crucial role in promoting communication between neurons and are essential for functions such as learning, memory, and overall neural activation.

In contrast, other options focus on inhibitory functions or effects related to mood and calmness, which do not align with the fundamental role of excitatory neurotransmitters. The distinction is essential in understanding how excitatory signals contribute to neural activity as opposed to inhibitory signals that work to suppress or reduce neuronal firing.