Auditory evoked magnetic fields to tones and pseudowords in healthy children and adults.
Neuromagnetic responses to tones and pseudowords were measured with a 24-channel magnetometer in nine adults and in 23 children, the latter aged 0.3-15 years. Both stimulus types elicited substantially similar responses in all subjects. At 0.9-s interstimulus interval (ISI), the adult response was a stable P1m-N1m-P2m-N2m sequence peaking at 50, 100, 200, and 250 ms, respectively. A biphasic P1m-N1,2m response with peaks at 100 and 260 ms occurred in children up to 12 years of age. At longer ISIs (1.2-2.4 s), an adult-type N1m response appeared in most children. N1m amplitude suppression at short ISIs was stronger in children than in adults and may reflect a longer refractory period of the N1 generator neurons during early childhood than later in life. Peak latencies of P1m, N1m, and N2m decreased with age, most rapidly < 7 years of age. All deflections originated in nearby cortical areas within the posterior sylvian fissure, and may serve as functional landmarks for that anatomic area.
Paetau
R
R
Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland.
Ahonen
A
A
Salonen
O
O
Sams
M
M
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D001303:Auditory Cortex / Q000502:physiology; D001931:Brain Mapping; D002648:Child; D002675:Child, Preschool; D004292:Dominance, Cerebral / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D015225:Magnetoencephalography; D008297:Male; D010898:Pitch Perception / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D012032:Refractory Period, Electrophysiological / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013067:Speech Perception / Q000502:physiology*