Chemical neurotransmission discovery

None of this explains why memory is pre-empted. Nor does it explain how PGO waves arise in REM sleep. To unlock those puzzles, we needed the key provided by the discovery of control by neurons, i.e. neuromodulation, a special kind of chemical neurotransmission by which the brain is able to change its state... 

The vital role of the acetylcholine-hydrolyzing enzyme AChE in terminating cholinergic neurotransmission has been recognized for almost as many years as ACh has been recognized as a neurotransmitter (Dale, 1914a, b). For nearly as long, AChE research was intimately linked to the study of its inhibitors [Loewi et al, 1926, cited in Loewi s Nobel lecture (http //nobelprize.org/nobel prizes/medicine/ laureates/1936/loewi-lecture.html) and by Dale, 1962]. The vulnerabihty of cholinesterases to certain natural compounds promoted the discovery and synthesis of new inhibitors for use as pesticides, therapeutics, and, unfortunately, as chemical... 

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