Event-related brain potentials to change in rapidly presented acoustic stimuli in newborns

Event-related brain potentials of 28 newborns to pitch change were studied during quiet sleep under stimulus conditions that typically elicit mismatch negativity in adults. Rarely occurring deviant tones of 1100 Hz (probability 12%) were embedded among repeated standard tones of 1000 Hz in an oddball-sequence with an interstimulus interval of 425 ms. Two control conditions were also employed: In the first, the 1100-Hz stimulus was presented alone without the intervening standard stimuli, and in the second the deviant stimulus had a pitch of 1300 Hz. In all conditions the infrequent stimulus elicited in most newborns a slow positive deflection peaking at a latency of 250-350 ms. The response to the standard tone was very small. These results indicate passive detection of even a small pitch change based either on refractoriness to repetition or dishabituation to change, or both. Some evidence was also found for a mismatch negativity-like response overlapping with the positive response and appearing as a reduction of this positive deflection at a latency of a typical mismatch negativity.