Paper Info
Title
Decoding episodic memory in ageing: A Bayesian analysis of activity patterns predicting memory.
Abstract
Normal ageing is associated with a decline in episodic memory, and neuroimaging studies in older adults have shown reduced activity in prefrontal cortex and other regions critical for memory function in the young. However, older adults also activate additional regions, suggesting a degree of functional reorganisation that has been attributed variously to detrimental and adaptive changes. Evaluation of these competing hypotheses depends critically upon inferences about the relative location and distribution of activity that are not well supported by current univariate or multivariate analyses. Here, we employed a recently developed model-based multivariate 'decoding' approach (Friston at al., 2008) to re-analyse a rich episodic encoding dataset and examine directly how the patterns of activity change in ageing. We assessed which spatial activity patterns, within lateral prefrontal cortex, best predict successful memory formation. Bayesian model comparison showed that the older adults had more distributed and bilateral (fragmented) predictive patterns of activity in anterior inferior frontal gyrus and middle frontal gyrus. With this direct multivariate test for changes in patterns of activity, we replicate and extend earlier findings of reduced prefrontal lateralisation in ageing. These findings extend conclusions based on conventional analyses, and support the notion that ageing alters the spatial deployment of neuronal activity, to render it less spatially coherent and regionally specific. This greater distribution of activity in older adults was also linked to poorer individual memory performance, suggesting that it reflects neural ageing, rather than adaptive compensatory responses. (C) 2011 Elsevier Inc. All rights reserved.
Year
DOI
Venue
2012
10.1016/j.neuroimage.2011.08.071
NEUROIMAGE
Keywords
Field
DocType
Ageing,fMRI,Episodic memory,Multivariate,Decoding,Over-recruitment,Dedifferentiation,Compensation,Prefrontal cortex,Lateralisation
Developmental psychology,Episodic memory,Neuroscience,Recognition memory,Visual cortex,Working memory,Prefrontal cortex,Psychology,Cognitive psychology,Brain activity and meditation,Inferior frontal gyrus,Middle frontal gyrus
Journal
Volume
Issue
ISSN
59
2
1053-8119
Citations 
PageRank 
References 
4
0.46
15
Authors
2
Name
Order
Citations
PageRank
Alexa Morcom116316.47
K. J. Friston2430321.24