ABSTRACT
Convincing evidence that acetylcholine (ACh) is a neurotransmitter contained in a variety of central nervous system pathways has been available for some years (see Kasa 1 and Wainer et al., 2 for a broad overview), ACh occupying a historically senior position among neurotransmitter candidates. ACh was first described by Loewi (1921) as “Vagustoff’ in the frog heart. However, only in the last few years has the field of neuroanatomy allowed, after a growth in research technology, the unequivocal visualization of cholinergic structures. Convincing conclusions on the cholinergic neuroanatomy of the central nervous system were gained by using histochemical tools, including AChE pharmacohistochemistry, immunocytochemistry, and in situ hybridization procedures. In addition, the anatomic technology has benefited from an interdisciplinary strategy, and it is now possible to combine behavioral or physiological experiments with tracing and/or lesioning of neuronal pathways and with histochemical characterization of the pathways involved. These methodologies will be discussed briefly below.
