During childhood and adolescence, the human brain undergoes various micro- and macroscopic changes. Understanding the neurophysiological changes within this reorganizational process is crucial, as many major psychiatric disorders emerge during this critical phase of life. In electroencephalography (EEG), a widely studied signal component are alpha oscillations (~8-13 Hz), which have been linked to developmental changes throughout the lifespan. Previous neurophysiological studies have demonstrated an increase of the alpha peak frequency and a decrease of alpha power to be related to brain maturation. The latter results have been questioned by recent developments in EEG signal processing techniques, as it could be demonstrated that aperiodic (non-oscillatory) components in the EEG signal conflate findings on periodic (oscillatory) changes, and thus need to be decomposed accordingly. We therefore analyzed a large, openly available pediatric dataset of 1485 children and adolescents in the age range of 5 to 21 years, in order to clarify the role of alpha oscillations and aperiodic signal components in this period of life. We first replicated previous findings of an increase of alpha peak frequency with age. Our results further suggest that alpha oscillatory power decreases with increasing age, however, when controlling for the aperiodic signal component, this effect inverted such as the aperiodic adjusted alpha power parameters significantly increase with advanced brain maturation, while the aperiodic signal component flattens and its offset decreases. Thus, interpretations of these oscillatory changes should be done with caution and incorporate changes in the aperiodic signal. These findings highlight the importance of taking aperiodic signal components into account when investigating age related changes of EEG spectral power parameters.
bioRxiv Subject Collection: Neuroscience