Beta-band neural variability reveals age-related dissociations in human working memory maintenance and deletion

How do neural mechanisms for maintaining and removing information in working memory change with age? While older adults are known to experience declines in both processes, research has historically focused on maintenance. This study investigates whether the 'inhibition deficit theory'—which posits that difficulty clearing irrelevant information from working memory contributes to cognitive decline—can be supported by tracking beta-band neural variability across distinct phases of working memory.

Researchers monitored the brain activity of 20 younger and 21 older adults using EEG while they performed a delayed match-to-sample task with varying loads. The team focused on 'cross-trial neural variability'—a measure of brain dynamics that captures individual differences better than traditional averaged neural power. They analyzed two key windows: the maintenance phase (holding objects in mind) and the post-response phase (clearing memory after a decision).

The study found a clear age-related dissociation in how neural dynamics predict behavioral success. For younger adults, lower beta variability during maintenance was linked to better performance, suggesting that high-precision, stable beta activity is crucial for holding information. In contrast, older adults showed no such link during maintenance. Instead, their performance was strongly predicted by beta-band variability during the post-response deletion phase. This confirms that while younger adults rely on efficient maintenance, older adults' performance is primarily tethered to their ability to successfully 'clear out' old information to prepare for subsequent cognitive demands.

These results provide a mechanistic explanation for cognitive aging that aligns with the inhibition deficit theory. By showing that older adults struggle specifically with the deletion of used information, the findings suggest that interventions targeting the efficiency of memory 'clear-out'—rather than just maintenance—might be more effective in mitigating age-related cognitive decline. It also highlights that measuring neural variability offers a more sensitive tool for identifying individual differences than examining average brain activity.