Diminished Alpha Lateralization During Working Memory but Not During Attentional Cueing in Older Adults

Abstract

Aging has been associated with declined performance in tasks that rely on working memory (WM). Because attention and WM are tightly coupled, declined performance on a WM task in older adults could be due to deficits in attention, memory capacity, or both. We used alpha (8-14 Hz) power modulations as an index to assess how changes in attention and memory capacity contribute to decreased WM performance in older adults. We recorded the magnetoencephalogram in healthy older (60-76 years) and younger adults (18-28 years) while they performed a lateralized WM task. At matched difficulty, older adults showed significantly lower memory spans than younger adults. Alpha lateralization during retention was nearly absent in older adults due to a bilateral reduction of alpha power. By contrast, in younger adults alpha power was reduced only contralateral to the attended hemifield. Surprisingly, during the cue interval, both groups showed equal alpha lateralization. The preserved alpha lateralization during attentional cueing, and lack thereof during retention, suggests that reduced WM performance in older adults is due to deficits in WM-related processes, not deficits in attentional orienting, and that a compensatory mechanism in aging permits significant residual WM performance in the absence of alpha lateralization.

Probing the limits of alpha power lateralization as a neural marker of selective attention in middle-aged and older listeners

“…Our results, however, are also to some extent compatible with the findings by Mok et al (2016) and Leenders et al (2016). Mok and colleagues focused explicitly on older adults (i.e., 60-87 years) and observed intact alpha power lateralization and spatial cue benefit for behavior, while Leenders et al (2016) report preserved alpha power lateralization during spatial cueing but not during a subsequent working memory retention interval. Older adults were not found to be more easily distracted by irrelevant information than younger adults.…”

“…With more specific evidence on selective auditory attention in middle-aged or older adults missing, our hypotheses were based on the evidence available from younger adults who performed the same task, and on results from studies investigating age-related effects on the lateralization of alpha power in the context of visual working memory. Collectively, these results suggest that increasing age correlates with a less pronounced or even absent lateralization of alpha power (Sander et al, 2012;Hong et al, 2015;Leenders et al, 2016). Further evidence shows that younger and older participants also differ in their ability to uphold a heightened level of overall alpha power (Wöstmann et al, 2015a;Henry et al, 2017).…”

“…The comparison of results from the aging studies discussed above suggests that the link between the relative degree of lateralized alpha power and associated consequences for behavior across age is indeed an elusive one. That is, the diminished or absent lateralization of alpha power observed for older compared to younger adults is not consistently paired with pronounced differences at the behavioral level (Sander et al, 2012;Hong et al, 2015;Leenders et al, 2016).…”

“…To date, all of the available evidence on changes in alpha lateralization with age comes from visual studies that contrasted young (~18-30 years) to older (~60-80 years) adults (Sander et al, 2012;Hong et al, 2015;Leenders et al, 2016; but see Mok et al, 2016) while virtually nothing is known about the period where one might suspect age-related change to first surface, that is, middle adulthood (~40-60 years) (Raz, 2005). In light of the well-attested fact that middle-aged adults already show signs of a gradual, if subtle, decline in cognitive abilities and sensory fidelity including hearing (Lin, 2011;Fabiani, 2012), and with new results emerging on the intricate interplay of hearing abilities and maintenance of cognitive fitness Wayne & Johnsrude, 2015;Deal et al, 2016), targeting this age group should be a prime goal for the neuroscience of attention.…”

Unraveling the relation between EEG-correlates of attentional orienting and sound localization performance: a diffusion model approach

“…Our results suggested that older adults may in principle be able to recruit the same oscillatory mechanisms as younger adults when searching for a target among simultaneously present distractors (Klatt et al, 2018b). Although bayesian statistics were indecisive in whether the non-significant difference in alpha lateralization between age groups presents a true null effect, the preserved post-stimulus alpha lateralization corroborated a number of studies, showing intact alpha lateralization in older adults when anticipating an upcoming (lateralized) stimulus (Heideman et al, 2018;Leenders, Lozano-Soldevilla, Roberts, Jensen, & De Weerd, 2018;Tune et al, 2018). However, recent studies did not find alpha lateralization in older adults, although they were still able to perform the task as well as their younger counterparts (Hong et al, 2015;van der Waal, Farquhar, Fasotti, & Desain, 2017).…”