What is the function of excitatory neurotransmitters?

Excitatory neurotransmitters play a crucial role in the communication between neurons by facilitating the depolarization of postsynaptic neurons. When these neurotransmitters bind to their respective receptors on the postsynaptic membrane, they typically lead to the opening of ion channels that allow positively charged ions, such as sodium (Na+), to enter the neuron. This influx of positive charge reduces the negativity inside the neuron, moving its membrane potential closer to the threshold needed to trigger an action potential.

The primary effect of excitatory neurotransmitters is to increase the likelihood that the postsynaptic neuron will fire an action potential, which is essential for transmitting signals throughout the nervous system. These neurotransmitters can be involved in various processes, including muscle contraction, sensory perception, and cognitive functions like learning and memory.

In contrast, the other options describe different mechanisms or functions of neurotransmitters that are not characteristic of excitatory neurotransmitters. For example, hyperpolarization and inhibition of action potentials pertain to the action of inhibitory neurotransmitters, while hormone regulation refers to a different aspect of neurobiology not related to excitatory synaptic transmission.