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Abstract:
Abstract: The present investigation was undertaken to
examine: 1) whether there are maturational changes in latency and
amplitude of mismatch negativity (MMN) in normally-developing
infants and pre-school children, and 2) whether MMN is reliably
elicited across age groups. This second question is of major
concern because of the desire to use MMN for clinical purposes. Two
experiments were conducted. Infants were aged 2-47 and 3-44 months
in experiments 1 and 2, respectively. In experiment 1, a 1200 Hz
deviant replaced a 1000 Hz standard. MMN was not observed in any
individual baby within the first year of life. By 13-18 months MMN
began to emerge in a few infants, with the first evidence of a
clear negativity by 31-47 months. In experiment 2, a larger
difference in frequency was employed with a 2000 Hz deviant
replacing a 1000 Hz standard. MMN was reliably elicited in 50 of
the 52 infants tested. A significant negative correlation was
observed between MMN latency and age. The morphology of the
event-related potential to the deviant stimulus for infant groups
3-7, 8-12, and 13-18 months indicated differential processing
between experiments. A possible masking effect of the MMN by a
positive component to the deviant is suggested to account for the
absent MMN in the first study.
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