Oscillatory alpha and aperiodic neural correlates of visual working memory and attention

To date, the physiological mechanisms that support visual working memory (WM) remain poorly understood. One reason is that a typical WM task is unable to distinguish between multiple underlying sub-processes (e.g. perception, attentional control, consolidation/storage), which map onto different neural signals. We used a modified change detection task sequence to examine electroencephalography (EEG) correlates of perception, attentional engagement, and memory consolidation/storage in a sample of 42 individuals. Additionally, we applied a novel analysis approach designed to disentangle the aperiodic and oscillatory components of the EEG signal during the prestimulus and the poststimulus period. We observed: (i) aperiodic parameters were significantly elevated during the pretrial period of the memory consolidation/storage task variant compared to the perception and attention task variants; (ii) prestimulus aperiodic parameters and oscillatory alpha were significantly associated with WM capacity and attentional control, respectively; and (iii) unexpectedly, higher oscillatory alpha was associated with better attentional engagement across participants, as well as within participants. Poststimulus aperiodic parameters and alpha oscillations showed a load-dependent effect in the poststimulus period; however, these parameters were not associated with task performance. This work suggests that aperiodic and alpha oscillatory elements of the EEG signal may serve unique roles in WM capacity and attention.