Modulation of aperiodic EEG activity provides sensitive index of cognitive state changes during working memory task

Frelih, Tisa (author), Matkovič, Andraž (author), Mlinarič, Tjaša (author), Bon, Jurij (author), Repovš, Grega (author)

To better understand cognitive processes, it is valuable to consider both periodic (oscillatory) and aperiodic electrophysiological brain activity. The aim of this study was to clarify how the periodic and aperiodic electrophysiological components reflect the cognitive processes involved in working memory. Fifty-seven human participants performed an n-back task while their brain activity was recorded using EEG. The analysis of both components of the EEG spectrum during task performance indicates that both periodic and aperiodic activities exhibit distinct task-related spatiotemporal dynamics that are closely related to cognitive demands. The results suggest that a substantial portion of the changes often attributed to theta oscillations in working memory tasks may be influenced by shifts in the spectral slope of aperiodic activity. This finding indicates that the modulation of aperiodic activity, associated with cognitive control processes, could provide a more sensitive index of cognitive state changes than previously recognised. To further confirm our findings, we also used these analysis methods in an item-recognition task, which showed similar patterns of periodic and aperiodic activity. These observations challenge the conventional understanding of low-frequency oscillations in cognitive processing and raise concerns about the routine practice of EEG baseline correction in time-frequency analysis, as it may obscure significant modulations in continuous working memory tasks. Consequently, the inclusion of aperiodic activity as a fundamental component of EEG analysis is likely to be critical for the accurate representation of the neural basis of cognition.

• Language: English
• Keywords: aperiodic activity, theta oscillations, working memory, n-back task, electroencephalography, neurosciences, brain, cognitive processes
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FF - Faculty of Arts
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 40 str.
• Numbering: Vol. 13, art. RP101071
• PID: 20.500.12556/RUL-176066
• UDC: 159.91:612.82
• ISSN on article: 2050-084X
• DOI: 10.7554/eLife.101071.4
• COBISS.SI-ID: 257996547
• Publication date in RUL: 20.11.2025

Record is a part of a journal

• Title: eLife
• Shortened title: eLife
• Publisher: eLife Sciences Publications
• ISSN: 2050-084X
• COBISS.SI-ID: 523069721

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: aperiodična aktivnost, theta oscilacije, delovni spomin, naloga n-nazaj, elektroencefalografija EEG, nevroznanost, možgani, kognitivni procesi