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Abstract:
The purpose of this study was to examine changes in the
topography of the mismatch negativity with maturation. 51 subjects
were studied in five age groups: adults (n=12), 9-10 year olds
(n=14), 7-8 year olds (n=14), 5-6 year olds (n=15) and 4 year olds
(n=10). Stimuli were 85 dB peSPL 1000 Hz and 1200 Hz tones
presented bilaterally using an oddball paradigm (deviant
probability=0.15). Event-related potentials were collected using
electrodes placed at 31 locations on the scalp and referenced to an
electrode on the nose. Subjects ignored the stimuli during the
recording. The mismatch negativity was examined in difference
waveforms calculated for each subject by subtracting waveforms
obtained in response to stimuli presented as standards from
waveforms obtained in response to stimuli presented as deviants.
The topography of the MMN was evaluated using scalp current density
(SCD) analysis. Systematic changes in MMN topography across the age
groups were observed. These include a shift to a more medial
location in the older groups and greater hemispheric asymmetry in
children than adults. These topographic changes indicate that the
MMN generators, or their orientation, are not yet mature by 10
years of age.
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