Power struggles: Absolute vs. relative EEG power in developmental neuroscience

Area of Science:

• Neuroscience
• Developmental Psychology
• Biomedical Engineering

Background:

• Resting electroencephalography (EEG) is crucial for studying brain development.
• A key methodological choice involves quantifying spectral activity using absolute or relative power.
• The theoretical underpinnings and consistent application of these measures, especially in pediatric samples, require further evaluation.

Purpose of the Study:

• To evaluate whether relative power in EEG spectral analysis is less biased by common sources of non-neural variability compared to absolute power.
• To integrate conceptual analysis with empirical data from pediatric samples.
• To provide recommendations for improving the interpretability and reproducibility of developmental EEG findings.

Main Methods:

• Conceptual analysis of absolute and relative power metrics in EEG.
• Empirical evaluation using data from multiple pediatric samples.
• Comparison of absolute and relative power across different frequency bands (e.g., theta, gamma).

Main Results:

• Absolute and relative EEG power measures showed both convergence and divergence across frequency bands.
• Higher frequency activity (gamma) aligned across indices, while lower frequency activity (theta) diverged.
• Relative power partially mitigated amplitude-related effects (e.g., fatigue) but remained influenced by factors like hair texture, affect, and time of day.

Conclusions:

• Relative power does not universally correct for non-neural or state-related variability in developmental EEG.
• Both absolute and relative power provide complementary representations of spectral composition.
• Developmental EEG studies should report both measures, justify analytic choices, and account for covariates to enhance interpretability and reproducibility.