Acetylcholine affects the spatial scale of attention: evidence from Alzheimer's disease |
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Authors: | Levy J A Parasuraman R Greenwood P M Dukoff R Sunderland T |
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Affiliation: | Geriatric Psychiatry Branch, National Institute of Mental Health, USA. jlevy2@dmc.org |
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Abstract: | Location precues were used to manipulate the spatial scale of attention in visual search for a target in an array of letters in patients with dementia of the Alzheimer type (DAT) and in age-matched older controls. Cue size varied in the amount of spatial precision conferred. Scopolamine, a muscarinic antagonist, decreased overall arousal and broadened spatial attention after a precise precue (small and valid) to target location for DAT patients but not for controls, suggesting a selective effect for attentional impairment induced by cholinergic blockade. In contrast, physostigmine, a cholinesterase inhibitor, did not alter the distribution of spatial attention relative to no-drug baseline testing for patients. Results support a differential role for cholinergic mechanisms in the modulation of the spatial scale of visual attention. |
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