This course considers the process of neurotransmission, especially chemicals used in the brain and elsewhere to carry signals from nerve terminals to the structures they innervate. The class focuses on monoamine transmitters (acetylcholine; serotonin; dopamine and norepinephrine); it also examines amino acid and peptide transmitters and neuromodulators like adenosine. Macromolecules that mediate neurotransmitter synthesis, release, inactivation, and receptor-mediated actions are discussed, as well as factors that regulate their activity and the second-messenger systems they control.