Sex differences in the lateralization of sustained electrophysiological response to 40 Hz clicks in typically developing preschoolers.

Two EEG-responses to periodical auditory 40-Hz stimulation - auditory steady-state response (ASSR) and sustained wave (SW) - are important neurophysiological correlates of temporal and spectral aspects of auditory perception, respectively. However, little is known about the sex difference of their development in children of 3-6 years, the period of extensive language acquisition. We registered a 32-channel electroencephalogram (EEG) while 500-ms 40-Hz click trains (n = 150) were presented to 57 typically developing children (27 females). We also assessed total language skill, expressive and receptive speech abilities, the perception of speech in noise and pseudowords repetition. 40-Hz ASSR was not very clearly expressed in our sample but showed developmental increase for both boys and girls. Topography of SW showed significant right-hemisphere predominance in boys, while girls had more symmetric response. On a subsample of boys (n = 14) we also found that the laterality index of SW correlated with speech in noise repetition score: the greater rightwarded the laterality was, the worse boys repeated words in noise. Our results are also consistent with the findings of greater lateralization of some components of EEG-activity in men.