Spatiotemporal maturation of the central and lateral N1 components to tones

This paper examines maturational changes in the spatiotemporal features of central and lateral NI components of the auditory evoked potentials (AEPs) to tone stimuli presented with a long stimulus onset asyncrony (SOA; 4200 m s) using the scalp current density (SCD) technique. A group of typically de veloping children ranging from 6 to 12 years of age and a group of adults w ere studied. Recently studies have begun to explore the topography of these components in children. These studies, however, often used rapidly present ed stimuli and did not elicit observable central N1s in the younger childre n. Our stimuli elicited both central and lateral Nts. Peak latencies of bot h components decreased with age. Peak amplitude also decreased with age for the lateral NI but not for the central Nl. Consequently, the difference be tween the lateral N1 and the central N1 amplitudes (or the ratio of lateral N1 amplitude to central N1 amplitude) also decreased with age, dramaticall y altering the morphology of the elicited AEP waveforms. Topography of the lateral N1 did not change with age. The location of maximal activation for the central N1 appeared to move more medially with age but this 'apparent' movement is probably due to the decreasing impact of the partially overlapp ing lateral N1 component whose amplitude is significantly smaller in adults than in children. (C) 2001 Elsevier Science BY All rights reserved.