Early development of electrophysiological activity: Contribution of periodic and aperiodic components of the EEG signal Rico Picó, Josué Moyano, Sebastián Conejero Barbero, Ángela Hoyo Ramiro, Ángela Victoria Ballesteros Duperon, María Ángeles Rueda Cuerva, María Del Rosario Alpha Aperiodic EEG activity Beta Development Infancy Periodic EEG activity Resting EEG Theta Toddlerhood This study was funded by two grants from the MCIN/ AEI/10.13039/501100011033 (ref. PID2020-113996GB- I00 and PSI2017-82670-P) awarded to MMR. Brain function rapidly changes in the first 2 years of life. In the last decades, resting-state EEG has been widely used to explore those changes. Previous studies have focused on the relative power of the signal in established frequency bands (i.e., theta, alpha, and beta). However, EEG power is a mixture of a 1/f-like background power (aperiodic) in combination with narrow peaks that appear over that curve (periodic activity, e.g., alpha peak). Therefore, it is possible that relative power captures both, aperiodic and periodic brain activity, contributing to changes in electrophysiological activity observed in infancy. For this reason, we explored the early developmental trajectory of the relative power in theta, alpha, and beta frequency bands from infancy to toddlerhood and compared it with changes in periodic activity in a longitudinal study with three waves at age 6, 9, and 16 to 18 months. Finally, we tested the contribution of periodic activity and aperiodic components of the EEG to age changes in relative power. We found that relative power and periodic activity trajectories differed in this period in all the frequency bands but alpha. Furthermore, aperiodic EEG activity flattened between 6 and 18 months. More importantly, only alpha relative power was exclusively related to periodic activity, whereas aperiodic components of the signal significantly contributed to the relative power of activity in theta and beta bands. Thus, relative power in these frequencies is influenced by developmental changes of the aperiodic activity, which should be considered for future studies. 2023-07-14T11:31:28Z 2023-07-14T11:31:28Z 2023-06-15 info:eu-repo/semantics/article Rico- Picó, J., Moyano, S., Conejero, Á., Hoyo, Á., Ballesteros-Duperón, M. Á., & Rueda, M. R. (2023). Early development of electrophysiological activity: Contribution of periodic and aperiodic components of the EEG signal. Psychophysiology, 00, e14360. [https://doi.org/10.1111/psyp.14360] https://hdl.handle.net/10481/83744 10.1111/psyp.14360 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivatives 4.0 Internacional Wiley