Maternal care during the first week postpartum has long-term consequences for offspring development in rodents. However, mother-infant interactions continue well beyond this period, with several physiological and behavioral changes occurring between days 18 and 28 PN. In the present study, we investigate the long-term effects on offspring behavior of being weaned at day 21 PN versus day 28 PN. We found that male and female offspring engage in higher initial levels of social interaction if weaned at day 28 PN, as well as sexually dimorphic changes in exploratory behavior. Females who were themselves weaned earlier also appeared to wean their own pups earlier. Sex-specific effects of weaning age were found on levels of oxytocin and vasopressin V1a receptor density in the hypothalamus, central nucleus of the amygdala and nucleus accumbens. These results indicate that altering weaning age in mice may be a useful model for investigating the development of sexual dimorphism in neurobiology and behavior.

Objective-The hypothesis is tested that electrocortical functional connectivity (quantified by coherence) of extremely low birth weight (ELBW) infants, measured at term post menstrual age, has regional differences from that of full term infants.Methods-128 lead EEG data were collected during sleep from 8 ELBW infants with normal head ultrasound exams and 8 typically developing full term infants. Regional spectral power and coherence were calculated.Results-No significant regional differences in EEG power were found between infant groups. However, compared to term infants, ELBW infants had significantly reduced interhemispheric coherence (in frontal polar and parietal regions) and intrahemispheric coherence (between frontal polar and parieto-occipital regions) in the 1-12 Hz band but increased interhemispheric coherence between occipital regions in the 24-50 Hz band.Conclusions-ELBW infants at term post menstrual age manifest regional differences in EEG functional connectivity as compared to term infants.Significance-Distinctive spatial patterns of electrocortical synchrony are found in ELBW infants. These regional patterns may presage regional alterations in the structure of the cortex.

Objective To quantify spectral power in frequency specific bands and commonly observed types of bursting activities in the EEG during early human development. Methods An extensive archive of EEG data from human infants from 35 to 52 weeks postmenstrual age obtained in a prior multi-center study was analyzed using power spectrum analyses and a high frequency burst detection algorithm. Results Low frequency power increased with age; however, high frequency power decreased from 35 to 45 weeks. This unexpected decrease was largely attributable to a rapid decline in the number of high frequency bursts. Conclusions The decline in high frequency bursting activity overlaps with a developmental shift in GABA's actions on neurons from depolarizing to hyperpolarizing and the dissolution of the gap junction circuitry of the cortical subplate.

We report mid-aortic syndrome (MAC) in two preterm infants. Both infants developed malignant hypertension refractory to medical therapy and died early in infancy. Thus far, this account is of the two youngest patients with MAC. Journal of Perinatology (2012) 32, 390-392; doi:10.1038/jp.2011 Keywords: preterm; mid-aortic syndrome; hypertension Introduction Mid-aortic syndrome (MAS) is a rare but important cause of renovascular hypertension in children and young adults. 1 It is characterized by segmental narrowing of the distal thoracic or abdominal aorta and stenosis of one or both renal arteries and major splanchnic vessels. 1-6 Diagnosis of MAS in premature infants is rare; this report describes the presentation and clinical course in two such patients. Case Patient 1The patient was a male infant born to a 20-year-old G 2 P 1 woman. Fetal Echocardiogram (ECHO) at 27 weeks detected premature closure of the ductus arteriosus, diminished right ventricular (RV) systolic function and RV hypertrophy. The patient was delivered by cesarean section at 28 weeks for worsening RV function. He required intubation, chest compressions and intratracheal epinephrine for apnea and bradycardia at 2 min of life. APGAR scores were 7, 1 and 7, at 1, 5 and 10 min, respectively. Birth weight was 1605 grams. Heart rate: 180 beats per min, respiratory rate: 52 breaths per min, preductal and postductal saturations: above 95% on FiO 2 of 0.3 and conventional mechanical ventilator support. There was a significant blood pressure (BP) difference between the upper and lower extremities: right arm 78/43 mm Hg, left arm 52/39 mm Hg, right leg 37/27 mm Hg, left leg BP could not be obtained. He had no appreciable dysmorphic features. Breath sounds were normal; murmurs were absent. There was no hepatosplenomegaly or abdominal bruit. The right brachial pulse was well felt, but the left brachial and femoral pulses were diminished.Postnatal ECHO demonstrated a widely patent right aortic arch, a small ductus arteriosus and severely diminished RV systolic function. A computed tomography (CT) angiogram identified narrowing of the abdominal aorta just below the level of the origins of the celiac and superior mesenteric arteries that measured 1.4  1 mm at its narrowest infrarenal portion (Figure 1). The abdominal aorta then increased in diameter (2.7 mm  2.4 mm) just before the iliac bifurcation. Enlarged paraspinal/lumbar collaterals fed into the abdominal aorta at multiple levels. The renal arteries were diminutive without collateral supply to the kidneys. Renal ultrasound demonstrated normal sized kidneys. Serum creatinine levels peaked on the third day of life at 1.3 mg dl À1 and normalized to 0.6 mg dl À1 by the fourth week of life. Williams and 22q11 deletion syndrome were excluded by genetic testing.He remained on ventilator support for 5 days and was extubated to continuous positive airway pressure. He received inhaled nitric oxide and Dopamine for 3 days. The patient's course was marked by severe systemic hypertension with right arm systolic BP...