Abstract
Electroencephalography (EEG) studies investigating visuo-spatial working memory (vWM) in aging typically adopt an event-related potential (ERP) analysis approach that has shed light on the age-related changes during item retention and retrieval. However, this approach does not fully enable a detailed description of the time course of the neural dynamics related to aging. The most frequent age-related changes in brain activity have been described by two influential models of neurocognitive aging, the Hemispheric Asymmetry Reduction in Older Adults (HAROLD) and the Posterior-Anterior Shift in Aging (PASA). These models posit that older adults tend to recruit additional brain areas (bilateral as predicted by HAROLD and anterior as predicted by PASA) when performing several cognitive tasks. We tested younger (N = 36) and older adults (N = 35) in a typical vWM task (delayed match-to-sample) where participants have to retain items and then compare them to a sample. Through a data-driven whole scalp EEG analysis we aimed at characterizing the temporal dynamics of the age-related activations predicted by the two models, both across and within different stages of stimulus processing. Behaviorally, younger outperformed older adults. The EEG analysis showed that older adults engaged supplementary bilateral posterior and frontal sites when processing different levels of memory load, in line with both HAROLD and PASA-like activations. Interestingly, these age-related supplementary activations dynamically developed over time. Indeed, they varied across different stages of stimulus processing, with HAROLD-like modulations being mainly present during item retention, and PASA-like activity during both retention and retrieval. Overall, the present results suggest that age-related neural changes are not a phenomenon indiscriminately present throughout all levels of cognitive processing.
Highlights
A gradual decrement in visuo-spatial working memory marks the progression of physiological aging (Salthouse et al, 1991; Jenkins et al, 2000; Park et al, 2002), since this cognitive ability is implicated in several everyday activities (Davies and Logie, 1993)
The EEG marker usually extracted from this task is a posterior long-lasting deflection whose amplitude varies with increasing memory load, which has been interpreted as reflecting the number of elements maintained in the visuo-spatial working memory (vWM) buffer
The results indicated that event-related potential (ERP) modulations in aging mirrored Posterior-Anterior Shift in Aging (PASA)-like activations in a go/no-go task and were consistent with Hemispheric Asymmetry Reduction in Older Adults (HAROLD) in a landmark task
Summary
A gradual decrement in visuo-spatial working memory (vWM) marks the progression of physiological aging (Salthouse et al, 1991; Jenkins et al, 2000; Park et al, 2002), since this cognitive ability is implicated in several everyday activities (Davies and Logie, 1993). The behavioral reduction in vWM capacity typical of old age is mirrored at the neural level by an attenuated CDA amplitude and/or amplitude modulation as a function of load (Jost et al, 2011; Sander et al, 2011; Störmer et al, 2013; Schwarzkopp et al, 2016; Tagliabue et al, 2019, 2020a)
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