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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 The Authors. Psychophysiology published by Wiley Periodicals LLC on behalf of Society for Psychophysiological Research.)

Error detection is one of the functions of the executive attention network, a brain system involved in executive control that includes the anterior cingulate cortex and other prefrontal regions. Despite the key role of this function in a wide range of life outcomes, very limited research has examined the early development of the network and whether its functional efficacy is related to environmental factors. Electrophysiological studies with adults have shown oscillatory activity in theta (4-7 Hz) range arising from medial frontal cortex that follows the detection of self-committed or observed errors. In the current study, we designed a novel experimental procedure that involved a familiarization phase with simple three-pieces puzzles followed by an experimental phase in which toddlers observed the puzzles being formed either correctly or incorrectly. Observation of incorrect configurations produced increased potentials in midline channels and greater power theta activity for both toddlers (n = 56) and adults (n = 14). In addition, socioeconomic status of the family in general, and parental education in particular, contributed to individual differences in the amplitude of the error-related signal and associated theta power in toddlers, indicating that children raised in lower SES families show poorer activation of the executive attention network. These data demonstrate the influence of environmental factors at the earliest stages of development of the executive attention network. Importantly, the results show that error-detection EEG signals can be used as neural markers of the initial development of executive attention, which can be of great help for the early detection of risk for developmental disorders involving deficits in this function., (© 2016 John Wiley & Sons Ltd.)