The influence of infant diet on early developmental changes in processing human voice speech stimuli: ERP variations in breast and milk formula-fed infants at 3 and 6 months after birth.

The purpose of this investigation was to determine if processing of language stimuli during the first half year of life in breast-fed infants differs from that of formula-fed infants. This question was addressed by examining the brain event-related potentials of healthy infants receiving breast milk (n = 15) or milk-based formula (n = 18) recorded in response to consonant vowel syllables presented in an oddball paradigm. The same infants were studied when they were 3-months and 6-months-old. The two groups were comparable on several measures relating to biological and home environment variables previously reported to influence development, including gestation period, birth weight, mother's IQ, and family socioeconomic status, and did not differ in weight or mental or motor development at the times of the visits. In general, ERP response features previously documented in studies of syllable processing in 3-6-month-old infants were observed in this study, including positive components at asymptotically equal to 190 msec (P1), asymptotically equal to 370 msec (P2), and asymptotically equal to 600 msec (P600), and negative components at asymptotically equal to 250 msec (N250), asymptotically equal to 450 msec (N450), and a late, negative going slow wave between 655 and 995 msec (LSW). For both groups there were instances where specific components were either poorly defined, e.g., P1 and N250 to the infrequent syllable at 3 months, N450 and P600 to this syllable at both ages, or not present in many infants, e.g., the P600 to the frequent syllable at 6 months. These variations appeared to be related to individual differences in development or paradigm-related features, i.e., ISI and frequency of syllable occurrence.