Age-related changes to the neural correlates of working memory which emerge after midlife.

Helen N Macpherson,Kathryn A Ellis,Richard Silberstein,Con Stough,David Camfield,Andrew Pipingas,David J White

doi:10.3389/fnagi.2014.00070

Helen N Macpherson, Kathryn A Ellis + Show 5 more

Open Access

https://doi.org/10.3389/fnagi.2014.00070

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Abstract

Previous research has indicated that the neural processes which underlie working memory change with age. Both age-related increases and decreases to cortical activity have been reported. This study investigated which stages of working memory are most vulnerable to age-related changes after midlife. To do this we examined age-differences in the 13 Hz steady state visually evoked potential (SSVEP) associated with a spatial working memory delayed response task. Participants were 130 healthy adults separated into a midlife (40–60 years) and an older group (61–82 years). Relative to the midlife group, older adults demonstrated greater bilateral frontal activity during encoding and this pattern of activity was related to better working memory performance. In contrast, evidence of age-related under activation was identified over left frontal regions during retrieval. Findings from this study suggest that after midlife, under-activation of frontal regions during retrieval contributes to age-related decline in working memory performance.

Highlights

Working memory is vulnerable to the effects of age and changes to the neural correlates of working memory occur across the lifespan (Babcock and Salthouse, 1990; Rypma and D’Esposito, 2000)
state visually evoked potential (SSVEP) RESULTS: WORKING MEMORY TASK EFFECTS ACROSS ALL PARTICIPANTS Figure 3 shows that when the working memory task was compared to the control task, the largest statistical effects (p < 0.01) occurred in two major frontal profiles of activity
SSVEP RESULTS: WORKING MEMORY AGE DIFFERENCES There were no correlations between age and the SSVEP which met the criteria for statistical significance, a figure of these results is not shown

Summary

Introduction

Working memory is vulnerable to the effects of age and changes to the neural correlates of working memory occur across the lifespan (Babcock and Salthouse, 1990; Rypma and D’Esposito, 2000). Increased reliance on frontally-mediated executive processes may represent a compensatory mechanism which is beneficial for cognitive performance (Reuter-Lorenz and Cappell, 2008), indicating that not all age-related differences in brain activation represent declining cognitive performance. Additional activity must be observed in high performing seniors or when performance is equivalent to younger adults. Based on this definition, it is recognized that age-related increases in activation can represent both compensatory processes in some brain regions and concomitant loss of neural specialization in others (Rossi et al, 2004; Davis et al, 2008). It has been postulated that such compensatory processes may reflect the adoption of reactive rather than proactive control strategies (Paxton et al, 2008), leading to age-equivalent performance in the presence of differential patterns of neural activation (Grady, 2012)

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