Maturation of obligatory auditory responses and their neural sources: Evidence from EEG and MEG

Neural auditory responses are known to change from childhood to adulthood. The most prominent components of the event-related potentials (ERPs) found in children are the P1 and N2, while the PI and N1 are strongest in adults. Previous dipole localizations showed regions of the auditory cortex (AC) underlying these responses. An NI in children, however, has only been observed in older age or under certain experimental conditions different than commonly applied in adults. The current study aimed to further elucidate on auditory processing and related components in school-aged children. To do this. MEG and EEG was recorded in adults and 9 to 10 year old children, while presenting pure tones either repetitively or randomly among tones of different pitch. Furthermore, the current paradigm was explicitly designed to not only investigate the PI and N2 in children, but moreover to examine NI modulations based on different refractory states caused by the two conditions. Our results are clear cut. In adults, P1(m) and N1 ( m) components were localized in AC regions, with the N1(m) largely attenuated for repetitive tones. The P1( m) and N2(m) components observed in children were also localized in AC regions. Most importantly, ERP modulations in the NI time window (i.e., larger responses for random than repetitive tones) were remarkably similar for adults and children, both in amplitude and latency. This effect indicates that the NI sub-component reflecting frequency-specific refractoriness is fully developed in 9 to 10 year old children. Thus, previous interpretations on the function and maturation of the NI need reconsideration. (C) 2011 Elsevier Inc. All rights reserved.