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Dopamine and memory dedifferentiation in aging

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Version 2 2023-06-12, 09:04
Version 1 2023-06-09, 17:23
journal contribution
posted on 2023-06-12, 09:04 authored by Hunar Abdulrahman, Paul C Fletcher, Edward Bullmore, Alexa MorcomAlexa Morcom
The dedifferentiation theory of aging proposes that a reduction in the specificity of neural representations causes declines in complex cognition as people get older, and may reflect a reduction in dopaminergic signaling. The present pharmacological fMRI study investigated episodic memory-related dedifferentiation in young and older adults, and its relation to dopaminergic function, using a randomized placebo-controlled double-blind crossover design with the agonist Bromocriptine (1.25 mg) and the antagonist Sulpiride (400 mg). We used multi-voxel pattern analysis to measure memory specificity: the degree to which distributed patterns of activity distinguishing two different task contexts during an encoding phase are reinstated during memory retrieval. As predicted, memory specificity was reduced in older adults in prefrontal cortex and in hippocampus, consistent with an impact of neural dedifferentiation on episodic memory representations. There was also a linear age-dependent dopaminergic modulation of memory specificity in hippocampus reflecting a relative boost to memory specificity on Bromocriptine in older adults whose memory was poorer at baseline, and a relative boost on Sulpiride in older better performers, compared to the young. This differed from generalized effects of both agents on task specificity in the encoding phase. The results demonstrate a link between ageing, dopaminergic function and dedifferentiation in the hippocampus.

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Publication status

  • Published

File Version

  • Published version

Journal

NeuroImage

ISSN

1053-8119

Publisher

Elsevier

Volume

153

Page range

211-220

Department affiliated with

  • Psychology Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2019-03-26

First Open Access (FOA) Date

2019-03-26

First Compliant Deposit (FCD) Date

2019-03-25

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