What is the main distinction between excitatory and inhibitory neurotransmitters?

The main distinction between excitatory and inhibitory neurotransmitters lies in their effects on the post-synaptic neuron. Excitatory neurotransmitters enhance nerve impulse transmission by depolarizing the membrane of the receiving neuron, increasing the likelihood that it will generate its own nerve impulse. This process often involves the opening of sodium channels, allowing positively charged ions to flow into the neuron, which drives the membrane potential closer to the threshold for firing an action potential.

In contrast to excitatory neurotransmitters, inhibitory neurotransmitters function to decrease the likelihood of a nerve impulse firing in the post-synaptic neuron. They typically do this by hyperpolarizing the membrane or stabilizing it, making it less responsive to incoming signals. This fundamental function of excitatory neurotransmitters as facilitators of signal transmission is what distinguishes them in the context of neuronal communication.