Developmental aspects of language processing in delta, theta, alpha and beta EEG bands

This study aimed to clarify the functional role of several EEG bands across age by analyzing language hemispheric lateralization in three linguistic tasks. Twenty-eight children, 22 young adults and 20 middle-aged participants were administered the same sample of written words and normalized amplitudes of delta, theta, alpha and beta bands were analyzed. Only young adults showed rightwards lateralization in delta frequency band. Task-dependent right-lateralization marked adults' theta and alpha distributions, whereas only linguistic vs. non-linguistic differences were found in children. Concerning the high-beta band, all groups showed left-lateralized linguistic effects. In adults slow rhythms represent indices of active inhibition of task-irrelevant regions, but in children they marked incomplete automated linguistic processing. The high-beta band revealed task-relevant left hemisphere linguistic activity in all groups, therefore representing the most reliable EEG marker of language hemispheric dominance in children and adults.