The Locus Coeruleus/Noradrenergic System: Its Role in Regulating Working Memory /Attention and Interaction with the Cholinergic System
There is much evidence that the central cholinergic system plays an important role in the processes of learning and memory. Correlations have been found between the severity of cholinergic deficits and cognitive decline in patients with Alzheimer’s disease (AD) in clinical trials for cholinomimetic therapy against deficits associated with this disease. It has been reported that multiple neurotransmitter deficits occur in the brains of AD patients. It is, therefore, interesting that numerous populations of neurons and neurotransmitter systems are damaged simultaneously by cholinergic deficits in the AD brain, contributing to the severity of the memory dysfunctions in this disease. In particular, the AD brain has a severe noradrenergic deficit as evidenced by cell losses in the locus coeruleus (LC) and by reduced levels of noradrenaline, its metabolites, and synthetic enzymic activity.1 Bondrareff et al2 suggested that a subgroup of patients with AD characterized by a reduced number of LC neurons showed a more severe cognitive decline than AD patients with LC neuronal counts comparable to those of age-matched control subjects. Therefore, it seems to be important to clarify the roles of interactions between the NA and Ch systems in regulating cognitive function. In the present study, we clarified1 how the NA system participates in working memory and attention and determined2 whether NA/Ch interactions play an important role in mediating processes involved in working memory and attention.
KeywordsLocus Coeruleus Basal Forebrain Choice Reaction Time Maze Task Work Memory Performance
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