ABSTRACT
Acetylcholine (ACh) plays an important role within the striatum based on its abundant presence. In the cerebrum, the striatum has the highest expression of choline acetyltransferase, used in ACh synthesis, and acetylcholinesterase, used in ACh breakdown.1 ACh in the basal ganglia comes from two sources: long projection neurons from the pedunculopontine tegmental nucleus and the laterodorsal pontine tegmentum (brain stem ACh nuclei) and giant interneurons of Kölliker (large interneurons). The large aspiny interneurons account for only 1%–3% of all striatal neurons but have extensive arborizations.2 Rat models have shown that these cholinergic interneurons provide a tonically active source of Ach,3 providing a constant release of Ach. ACh binds to two different classes of receptors: nicotinic and muscarinic, both of which are found within the striatum.
