Serotonin is the primary neurotransmitter involved in depression.

Glutamate is the primary excitatory neurotransmitter in the CNS.

Glutamate is the brain's primary excitatory neurotransmitter.

Glutamate is the "primary excitatory neurotransmitter in the human nervous system", participating in a multitude of brain functions.

Dopamine is the primary neurotransmitter involved in the reward pathways in the brain.

The following is a brief table of notable drugs and their primary neurotransmitter, receptor or method of action.

GABA is the primary inhibitory neurotransmitter of the human brain.

In addition, extracellular levels of glutamate, the primary excitatory neurotransmitter in the brain, have been shown to increase upon exposure to amphetamine.

Dopamine is the primary neurotransmitter affected by methamphetamine, but norepinephrine and epinephrine are also affected.

Dopamine is the primary neurotransmitter of the reward circuit in the brain.