The Anatomical and Neurochemical Basis of Atropine-Resistant Neocortical Activation
The experiments discussed in Chapter 4 suggested the existence of two distinct activating inputs to the neocortex. In 1973 it seemed reasonable to think that a cholinergic component of the ascending reticular activating system was responsible for atropine-sensitive activation while some ascending noncholinergic system was responsible for atropine-resistant activation. Since there was evidence of various kinds to suggest the involvement of ascending noradrenergic fibres from the locus coeruleus in cortical activation, I suspected that atropine-resistant neocortical activation might be dependent on norepinephrine (noradrenalin).
KeywordsMonoamine Oxidase Lateral Hypothalamus Slow Wave Activity Spontaneous Motor Activity Serotonin Antagonist
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Notes on Chapter 5
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- 4.Watson, N.V., Hargreaves, E.L., Penava, D., Eckel, L.A., and Vanderwolf, C.H. (1992). Serotonin-dependent cerebral activation: effects of methiothepin and other serotonergic antagonists. Brain Research, 597: 16–23. A few years later, it became clear that atropine-resistant neocortical activation in urethane anesthetized rats is sensitive to serotonin antagonists that are ineffective in waking rats, indicating that, in some as yet undetermined manner, urethane modifies and increases the effect of serotonergic antagonists. [Dringenburg, H.C., Vanderwolf, C.H., and Hamilton, J.T. (1995). Urethane reduces contraction to 5hydroxytrytamine (5-HT) and enhances the action of the 5-HT antagonist ketanserin on the rat thoracic aortic ring. Journal of Neural Transmission, 101, 183–1931Google Scholar