Nicotinic acetylcholine receptors (nAChRs) are a type of receptor found in the central and peripheral nervous systems. They are activated by the neurotransmitter acetylcholine and are responsible for the fast excitatory synaptic transmission in the nervous system. nAChRs are ligand-gated ion channels, meaning they open and close in response to acetylcholine binding to the receptor. nAChRs are involved in a variety of neurological processes, including muscle contraction, learning and memory, pain perception, and addiction.