Resting gamma power during the postnatal critical period for GABAergic system development is modulated by infant diet and sex.

Gamma band activity (30-50 Hz) plays an essential role in brain development and function, but neither the early postnatal development nor subject and environmental factors influencing this development have been reported. We documented the development of resting gamma power using high density EEG recordings obtained each month from postnatal month 2 to 6 in 518 healthy infants who were breast-fed (170; 85 boys), fed milk formula (186; 97 boys), or fed soy formula (162; 90 boys). Gamma power was determined for 44 sites distributed over major brain regions and analyses were adjusted for background variables relevant to neurodevelopment. The results show gamma power follows a gradually increasing function across this time period that varies in topographic magnitude and is differentially influenced by subject and environmental variables-among which gestation, head circumference, and infant diet-sex interactions figure most prominently. Relationships between gamma power and standardized measures of infant behavioral development appear to be emerging but are in flux during this time. Since this postnatal period is considered critical in the development of the GABAergic system underlying the generation of gamma activity, the observed findings may reflect organizational changes that will influence the future development of gamma-related behavioral and neurocognitive functions.

Infant Diet-Related Changes in Syllable Processing Between 4 and 5 Months: Implications for Developing Native Language Sensitivity.

Since maturational processes triggering increased attunement to native language features in early infancy are sensitive to dietary factors, infant-diet related differences in brain processing of native-language speech stimuli might indicate variations in the onset of this tuning process. We measured cortical responses (ERPs) to syllables in 4 and 5 month old infants fed breast milk, milk formula, or soy formula and found syllable discrimination (P350) and syntactic-related functions (P600) but not syllable perception (P170) varied by diet, but not gender or background measures. The results suggest breastfed and formula-fed infants differ in onset of this critical period in speech perception.

Infant diet, gender and the development of vagal tone stability during the first two years of life.

Postnatal nutrition influences neurodevelopment, but it is not known whether the development of individual differences in physiologic measures is related to variations in early postnatal diet. To address this issue we studied the stability of vagal tone (V)--an index of individual differences in parasympathetic heart rate control-by measuring resting V quarterly during infancy and again at 2 years in 146 breast-fed (BF), 143 milk formula-fed (MF), and 137 soy formula-fed (SF) infants. Stability of V across infancy was more consistently significant for BF than formula-fed infants. Stability was similar for boys and girls in BF and SF groups but was generally higher in boys than girls in the MF group. Significant stability between infancy and 2 years emerged later in SF than other groups and later in boys than girls. Stability generally peaked between 6 and 9 months-a time when postnatal vagal myelination slows and which may represent a pivotal stage in the development of V stability. These findings indicate that infant diet and gender are important modulators of the early development of autonomic state control.

Infant diet, gender and the normative development of vagal tone and heart period during the first two years of life.

Relationships between early postnatal diet and the development of cardiac regulation were studied using resting vagal tone and heart period measures obtained quarterly during infancy and at 2years in 158 breast-fed, 159 milk formula-fed, and 148 soy formula-fed infants. Both measures increased across time for all groups. Heart period was greater in boys than in girls-particularly in soy-fed infants. Higher vagal tone in girls than in boys was not strongly influenced by diet. At 1 and 2years measures differed among boys (soy-fed>breast-fed) but not among girls. Earlier slowing in breast-fed than in formula-fed infants in the rate of increase in vagal tone during infancy suggests that the timing of this developmental shift is sensitive to early infant diet. Finally, the findings do not indicate atypical development of cardiac activity in soy-fed infants that might be associated with estrogenic compounds in this formula.

Eating breakfast enhances the efficiency of neural networks engaged during mental arithmetic in school-aged children.

To determine the influence of a morning meal on complex mental functions in children (8-11 y), time-frequency analyses were applied to electroencephalographic (EEG) activity recorded while children solved simple addition problems after an overnight fast and again after having either eaten or skipped breakfast. Power of low frequency EEG activity [2 Hertz (Hz) bands in the 2-12 Hz range] was determined from recordings over frontal and parietal brain regions associated with mathematical thinking during mental calculation of correctly answered problems. Analyses were adjusted for background variables known to influence or reflect the development of mathematical skills, i.e., age and measures of math competence and math fluency. Relative to fed children, those who continued to fast showed greater power increases in upper theta (6-8 Hz) and both alpha bands (8-10 Hz; 10-12 Hz) across sites. Increased theta suggests greater demands on working memory. Increased alpha may facilitate task-essential activity by suppressing non-task-essential activity. Fasting children also had greater delta (2-4 Hz) and greater lower-theta (4-6 Hz) power in left frontal recordings-indicating a region-specific emphasis on both working memory for mental calculation (theta) and activation of processes that suppress interfering activity (delta). Fed children also showed a significant increase in correct responses while children who continued to fast did not. Taken together the findings suggest that neural network activity involved in processing numerical information is functionally enhanced and performance is improved in children who have eaten breakfast, whereas greater mental effort is required for this mathematical thinking in children who skip breakfast.