Age- and dementia-associated impairments in divided attention: psychological constructs, animal models, and underlying neuronal mechanisms.
Following a brief description of the psychological construct 'divided attention', impairments in divided attention and related executive functions are discussed as the major variable in the development and manifestation of age- and dementia-associated cognitive impairments. Neuropsychological and functional imaging studies in humans have indicated that dorsolateral and ventrolateral prefrontal, cingulate, parietal and premotor cortical areas are involved in the mediation of dual task performance. Furthermore, reduced activity in these areas has been suggested to mediate age- and dementia-associated impairments in divided attention. Experimental studies in animals have provided strong support for the hypothesis that cholinergic projections terminating in all cortical areas and layers crucially mediate the performance in tasks that tax processing capacity and/or the allocation of processing resources to competing demands. This specification of the 'cholinergic hypothesis' is evaluated in light of recent critical accounts of the role of this system in the development of age- and dementia- related cognitive disorders. The converging animal experimental and human neuropathological, as well as neuropsychological, evidence indicates that decreases in the integrity of cortical cholinergic inputs represent a necessary, possibly even sufficient, neuronal process mediating the impairments in divided attention and the resulting, broad decline in cognitive functions.
Sarter
M
M
Department of Psychology, Ohio State University, Columbus, Ohio 43210, USA. sarter2@osu.edu
Turchi
J
J
D000109:Acetylcholine / Q000378:metabolism*; D000375:Aging / Q000502:physiology / Q000523:psychology*; D000818:Animals; D001288:Attention / Q000502:physiology; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000378:metabolism / Q000503:physiopathology; D003704:Dementia / Q000378:metabolism / Q000503:physiopathology* / Q000523:psychology; D006801:Humans; D009483:Neuropsychological Tests
D000109:Acetylcholine