Acetylcholine (ACh) is a fast-acting, point-to-point neurotransmitter at the neuromuscular junction and in the autonomic ganglia; however, there are fewer demonstrations of similar actions in the brain (Changeux, 2010). Instead, central cholinergic neurotransmission predominantly changes neuronal excitability, alters presynaptic release of neurotransmitters, and coordinates the firing of groups of neurons (Kawai et al., 2007; Rice and Cragg, 2004; Wonnacott, 1997; Zhang and Sulzer, 2004). As a result, ACh appears to act as a neuromodulator in the brain, despite its role as the primary excitatory neurotransmitter in the periphery.
