Acetylcholine (ACh) is a neurotransmitter that is found in many areas in the nervous system. It is extremely important in movement, and is also involved in attention, arousal and memory. An example of an ACh agonist is nicotine. If you smoke tobacco, some of your ACh synapses will be stimulated by the nicotine that gets to the brain. At the synapses, the nicotine will behave just like acetylcholine by binding to ACh receptor sites and resulting in postsynaptic potentials.