Abstract
Background There is considerable uncertainty about the time-course of central auditory maturation. On some indices, children appear to have adult-like competence by school age, whereas for other measures development follows a protracted course.Methodology We studied auditory development using auditory event-related potentials (ERPs) elicited by tones in 105 children on two occasions two years apart. Just over half of the children were 7 years initially and 9 years at follow-up, whereas the remainder were 9 years initially and 11 years at follow-up. We used conventional analysis of peaks in the auditory ERP, independent component analysis, and time-frequency analysis.Principal Findings We demonstrated maturational changes in the auditory ERP between 7 and 11 years, both using conventional peak measurements, and time-frequency analysis. The developmental trajectory was different for temporal vs. fronto-central electrode sites. Temporal electrode sites showed strong lateralisation of responses and no increase of low-frequency phase-resetting with age, whereas responses recorded from fronto-central electrode sites were not lateralised and showed progressive change with age. Fronto-central vs. temporal electrode sites also mapped onto independent components with differently oriented dipole sources in auditory cortex. A global measure of waveform shape proved to be the most effective method for distinguishing age bands.Conclusions/SignificanceThe results supported the idea that different cortical regions mature at different rates. The ICC measure is proposed as the best measure of ‘auditory ERP age’.
Highlights
Two contrasting models of auditory maturation between childhood and adulthood are suggested by behavioral and imaging studies
Note that the Younger group at session 2 and the Older group at session 1 are both aged 9 years and their waveforms are similar. This is of interest for two reasons: it demonstrates replicability of findings across samples, and it indicates that the auditory event-related potentials (ERPs) is not influenced by prior experience of the task, but rather is a pure index of maturation
Our results strongly supported the work of Ponton and colleagues [7], who argued that auditory maturation could not be regarded as a unitary process, because different pathways mature at different rates
Summary
Two contrasting models of auditory maturation between childhood and adulthood are suggested by behavioral and imaging studies. Three of the largest studies, by Ponton et al [6], [7], [8], Albrecht et al [9] and Sharma et al [10] documented substantial changes in the auditory ERP, to click trains, tones and syllables respectively, from early childhood to adolescence, continuing into adulthood Inspection of their data suggested relatively little change in waveforms for children between 7 and 11 years. We focus on two complementary indices: (i) inter-trial coherence (ITC), a measure of the extent to which phase-locking occurs, and (ii) event-related spectral perturbation (ERSP), a measure of the increase in power in a frequency band after presentation of a signal, relative to baseline These measures are not just an alternative way of representing data: they are sensitive to features in the data that can get averaged out by conventional methods of analysis [18]. We predicted that inclusion of information from time-frequency analysis might give better prediction than reliance on waveform shape alone
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