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Biol Psychiatry. 2010 Mar 15;67(6):575-80. doi: 10.1016/j.biopsych.2009.12.013.

Simulating neurocognitive aging: effects of a dopaminergic antagonist on brain activity during working memory.

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1
Aging Research Center, Karolinska Institute, Stockholm, Sweden. hakan.fischer@ki.se

Abstract

BACKGROUND:

Previous correlational studies have indirectly linked dysfunctional dopaminergic neurotransmission to age-related cognitive deficits and associated reductions in task-induced functional brain activity.

METHODS:

We used an experimental-pharmacological functional magnetic resonance imaging (fMRI) approach to more directly examine the role of dopamine in neurocognitive aging. Twenty younger and 20 healthy older adults were included. During fMRI scanning, a spatial working memory (SWM) task was administered under two conditions, varying in cognitive load. Positron emission tomography measurements with the D1 receptor antagonist [(11)C]SCH23390 confirmed that a given experimental dose of unlabeled solution occupied 50% of D1 receptors in younger adults.

RESULTS:

An age-related reduction in SWM performance was observed, and fMRI data revealed that, relative to younger adults under placebo conditions, elderly persons under-recruited load-sensitive fronto-parietal regions during SWM. Critically, in younger adults, the D1 antagonist resulted in a similar reduction in SWM performance and fMRI response.

CONCLUSIONS:

These results suggest that depletion of dopamine, whether ontogenetically or pharmacologically, results in decreased SWM performance as well as reduced load-dependent modulation of the blood oxygen level dependent signal in fronto-parietal regions, possibly by decreasing the signal-to-noise ratio in relevant neural networks.

PMID:
20138255
DOI:
10.1016/j.biopsych.2009.12.013
[Indexed for MEDLINE]
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