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Effects of motor activity versus cognitive demand on asymmetries in EEG frequency bands and their relation to
Annakarina Mundorf1, Sarah A Merklein1,2, Petunia Reinke2,3
1Institute for Systems Medicine and Department of Human Medicine, MSH Medical School Hamburg, Hamburg, Germany.
Introduction:
Electroencephalography (EEG) is commonly used in neuroscience to study cognitive and emotional processes, often showing functional lateralization. Alpha asymmetries are frequently interpreted as a reverse marker of functional asymmetries in cognitive activation. However, the role of motor activity versus cognitive demands in driving EEG asymmetries remains unclear.
Methods:
To explore this, we analyzed resting-state and task-based EEG asymmetry from 610 healthy adults (ages 20-70) from the Dortmund Vital Study (ClinicalTrials.gov: NCT05155397). Participants completed three tasks with increasing hand involvement and cognitive demands: Psychomotor Vigilance, Simon, and Stroop tasks.
Results:
Timepoint (pre-stimulus vs. post-stimulus vs. resting-state) had the strongest impact, especially in the alpha and theta bands, with notable differences between resting-state and task-related asymmetries. Non-right-handers exhibited more dynamic shifts in asymmetry, while right-handers showed more stable lateralization patterns. Correlations between frequency bands, electrode pairs, and tasks revealed strong interhemispheric coupling in frontal and weaker coupling in central regions. Frontal post-stimulus asymmetry correlated more strongly than resting-state or pre-stimulus.
Discussion:
Findings suggest that EEG asymmetry is a dynamic process influenced by cognitive and/or motor activity and perceptual processes mediated by frontoparietal circuits, with implications for interpreting EEG biomarkers in both research and clinical settings. This study offers reference standards in EEG asymmetry research.
