Mismatch Negativity in Healthy Neonates and Premature Babies

Abstract

Objective: This study investigated the characteristics of mismatch negativity (MMN) recorded in early infancy and the effect of the perinatal condition on the MMN to determine whether recording MMN is useful for the early detection of mild cerebral dysfunction. Method: Auditory event-related potentials (ERPs) were recorded in 69 infants drawn from the neonatal intensive care unit and nursery room in Tokyo Women’s Medical University (TWMU). These subjects were classified into five groups according to their perinatal state: full-term neonates (Group NN); premature babies with no neurological complications (Group PN); seven premature babies with birth asphyxia (Group PA); premature babies with neurological abnormalities, but no birth asphyxia and no definite findings on echogram or brain computed tomography (CT; Group PD1); and premature babies with abnormalities on brain echogram or brain CT, such as periventricular leukoencephalopathy or periventricular leukomalacia (Group PD2). The ERPs were all recorded at about 40 weeks of gestational age using a high-density EGI electroencephalogram (EEG) system. The stimuli consisted of 1,000-Hz tones with 90 % probability as the standard and 1,200 Hz with 10 % probability as the deviant. We primarily evaluated the amplitude and latency MMN in the frontal and central regions. Results: There was a significant relationship between the amplitude of the MMN and the postconceptional age (PCA). In Groups PD2 and PA, the incidence of MMN was slightly lower than in Group NN, but some of the babies in Groups PD2 and PA had greater MMN amplitudes than the babies in the other groups. Conclusion: High-risk babies showed some abnormalities in MMN. We should further investigate the relationship between MMN abnormalities and developmental prognosis.