Development of the EEG from 5 months to 4 years of age

Objectives: This report provides a systematic longitudinal analysis of the EEG from infancy into early childhood. Particular emphasis is placed on the empirical confirmation of a 6–9 Hz alpha-range frequency band that has previously been used in the infant EEG literature. Methods: EEG data in 1-Hz bins from 3 to 12 Hz were analyzed from a longitudinal sample of 29 participants at 5, 10, 14, 24, and 51 months of age. Results: Inspection of power spectra averaged across the whole sample indicated the emergence of a peak in the 6–9 Hz range across multiple scalp regions. Coding of peaks in the power spectra of individual infants showed a clear developmental increase in the frequency of this peak. A rhythm in the 6–9 Hz emerged at central sites that was independent of the classical alpha rhythm at posterior sites. The relative amplitude of this central rhythm peaked in the second year of life, when major changes are occurring in locomotor behavior. Conclusions: The 6–9 Hz band is a useful alpha-range band from the end of the first year of life into early childhood. The findings also complement other research relating the infant central rhythm with the adult sensorimotor mu rhythm.