This is the side view of the human brain, facing left. The lights are showing you some of the places where neurons use acetylcholine as their neurotransmitter. We now zoom in on one of these neurons which uses acetylcholine. The cell body, located in the septal nucleus of the hypothalamus, sends its axon to the hippocampus. At the end of the axon is the terminal bouton. After the arrival of an action potential, vesicles containing acetylcholine fuse with the presynaptic membrane and release acetylcholine into the synaptic cleft.