# The Relationship Between Task‐Related Aperiodic EEG Activity, Neural Inefficiency and Verbal Working Memory in Younger and Older Adults

## TL;DR

This study explores how brain activity patterns, specifically aperiodic EEG exponents, relate to working memory efficiency in younger and older adults.

## Contribution

It provides new evidence linking flatter EEG exponents to neural inefficiency and shows that older adults can modulate these exponents to support working memory.

## Key findings

- Younger adults had steeper aperiodic EEG slopes than older adults.
- Flatter exponents during retention were associated with increased neural inefficiency but not necessarily worse performance.
- Older adults showed flexible modulation of exponents during retention, which supported better working memory performance.

## Abstract

Working memory (WM) decline in aging may be related to increases in “neural noise”, potentially reflected in the EEG aperiodic exponent. We reanalyzed previously published data to investigate age‐related differences in the aperiodic exponent during verbal WM and its relationship with neural inefficiency. EEG was recorded from 24 younger (18–35 years) and 30 older adults (50–86 years) during a modified Sternberg task with 1‐letter, 3‐letter, and 5‐letter load conditions. Younger adults consistently demonstrated steeper aperiodic slopes than older adults. Unexpectedly, both age groups showed decreased (i.e., flattened) aperiodic exponents during retention relative to fixation, with minimal load‐dependent effects. Notably, the relationship between task‐related exponent changes and WM performance was complex and dependent on the exponent at fixation, particularly in older adults. Finally, flatter exponents during fixation and late retention were associated with greater neural inefficiency during stimulus processing, reflected by increased P3b amplitudes without corresponding WM performance improvements. These findings suggest that flatter exponents are associated with less efficient neural processing and that older adults flexibly modulate their aperiodic exponent during retention to support WM performance.

This study provides some of the first evidence linking flatter aperiodic EEG exponents to neural inefficiency during working memory. While older adults showed flatter exponents during the task, consistent with previous research, flatter exponents alone were not associated with poorer performance. Instead, flexible modulation of exponents away from baseline during retention was associated with better task performance, particularly in older adults.