Changes in auditory cortex and the development of mismatch negativity between 2 and 6 months of age

Evoked responses to stimulus deviance were compared in infants between 2 and 6 months of age. A deviant stimulus containing a short silent gap occasionally replaced a repeating standard stimulus matched in duration, intensity and approximate spectral content. At two months, the standard stimuli evoked only a positive slow wave, and its amplitude was increased in response to the deviant stimuli. By 6 months, the deviant stimuli evoked an increased negativity at approximately 200 ms, similar to the mismatch negativity (MMN) response in adults. The results are considered with respect to layer-specific cortical maturation during this period.