What stops the impulse, producing a calming effect on the brain?

• A. Inhibitory neurotransmitters
• B. Excitatory neurotransmitters
• C. Dopamine
• D. Serotonin

Answer: (A)

The main idea here is how neural signals are dampened. Inhibitory neurotransmitters reduce the chance that a neuron will fire by making the inside of the neuron more negative, which lowers overall brain activity and creates a calming effect. The quintessential example is GABA, which opens chloride channels and hyperpolarizes the postsynaptic neuron, effectively stopping impulse transmission. That inhibitory action is what smooths out excessive activity. In contrast, excitatory neurotransmitters like glutamate push neurons toward firing, increasing arousal rather than calming things down. Dopamine and serotonin influence mood and motivation in more complex, context-dependent ways and aren’t the general mechanism for stopping impulses to produce a calming state.