Less wiring, more firing: low-performing older adults compensate for impaired white matter with greater neural activity.

dc.contributor.author

Daselaar, Sander M

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Iyengar, Vijeth

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Davis, Simon W

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Eklund, Karl

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Hayes, Scott M

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Cabeza, Roberto E

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United States

dc.date.accessioned

2015-07-13T15:09:40Z

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2015-04

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The reliable neuroimaging finding that older adults often show greater activity (over-recruitment) than younger adults is typically attributed to compensation. Yet, the neural mechanisms of over-recruitment in older adults (OAs) are largely unknown. Rodent electrophysiology studies have shown that as number of afferent fibers within a circuit decreases with age, the fibers that remain show higher synaptic field potentials (less wiring, more firing). Extrapolating to system-level measures in humans, we proposed and tested the hypothesis that greater activity in OAs compensates for impaired white-matter connectivity. Using a neuropsychological test battery, we measured individual differences in executive functions associated with the prefrontal cortex (PFC) and memory functions associated with the medial temporal lobes (MTLs). Using event-related functional magnetic resonance imaging, we compared activity for successful versus unsuccessful trials during a source memory task. Finally, we measured white-matter integrity using diffusion tensor imaging. The study yielded 3 main findings. First, low-executive OAs showed greater success-related activity in the PFC, whereas low-memory OAs showed greater success-related activity in the MTLs. Second, low-executive OAs displayed white-matter deficits in the PFC, whereas low-memory OAs displayed white-matter deficits in the MTLs. Finally, in both prefrontal and MTL regions, white-matter decline and success-related activations occurred in close proximity and were negatively correlated. This finding supports the less-wiring-more-firing hypothesis, which provides a testable account of compensatory over-recruitment in OAs.

dc.identifier

https://www.ncbi.nlm.nih.gov/pubmed/24152545

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bht289

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1460-2199

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https://hdl.handle.net/10161/10281

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eng

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Oxford University Press (OUP)

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Cereb Cortex

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10.1093/cercor/bht289

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DTI

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MTL

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PFC

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elderly

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fMRI

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frontal

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Aged

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Aging

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Brain Mapping

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Diffusion Tensor Imaging

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Executive Function

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Female

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Humans

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Magnetic Resonance Imaging

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Male

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Memory

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Neural Pathways

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Neuropsychological Tests

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Prefrontal Cortex

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Temporal Lobe

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White Matter

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Less wiring, more firing: low-performing older adults compensate for impaired white matter with greater neural activity.

dc.type

Journal article

duke.contributor.orcid

Davis, Simon W|0000-0002-5943-0756

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Cabeza, Roberto E|0000-0001-7999-1182

pubs.author-url

https://www.ncbi.nlm.nih.gov/pubmed/24152545

pubs.begin-page

983

pubs.end-page

990

pubs.issue

4

pubs.organisational-group

Center for Cognitive Neuroscience

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Center for Population Health & Aging

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Clinical Science Departments

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Duke

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Duke Institute for Brain Sciences

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Duke Population Research Institute

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Duke Science & Society

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Duke-UNC Center for Brain Imaging and Analysis

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Initiatives

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Institutes and Centers

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Institutes and Provost's Academic Units

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Neurology

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Neurology, Behavioral Neurology

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Psychiatry & Behavioral Sciences

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Psychiatry & Behavioral Sciences, Brain Stimulation and Neurophysiology

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Psychiatry & Behavioral Sciences, Geriatric Behavioral Health

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Psychology and Neuroscience

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Sanford School of Public Policy

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School of Medicine

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Trinity College of Arts & Sciences

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University Institutes and Centers

pubs.publication-status

Published

pubs.volume

25

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