Learning as adaptation of the infant

The present report advocates an adaptive, ecological approach to the study of learning in infants. Concepts of developmental niche and ontogenetic adaptation are applied to early mammalian development. Within this conceptual framework, it is asserted that learning cannot be fully understood separately from a behaving body; that learning is a dimension of behavior and physiology. The role of learning in the development of ingestive behavior, especially suckling and the transition to solid food, is used to illustrate the potential of studying learning in development. These considerations are offered as examples of an alternative approach to the empirical study of learning by infants. The approach advocated herein can be applied to clinical issues: developmental adaptations evolved in contexts that differ from our modern environments. Exposure to contexts or contingencies that are evolutionarily unexpected may inadvertently create pathology.     

Perinatal adaptation of the cardiovascular system.

The perinatal changes in the cardiovascular system were studied in fetal rats. The changes in the cardiovascular system occurred earlier than in humans. The ductus arteriosus closes in the rat in one and a half hours.     

Acute kidney injury in the fetus and neonate

Acute kidney injury (AKI) is an under-recognized morbidity of neonates; the incidence remains unclear due to the absence of a unified definition of AKI in this population and because previous studies have varied greatly in screening for AKI with serum creatinine and urine output assessments. Premature infants may be born with less than half of the nephrons compared with term neonates, predisposing them to chronic kidney disease (CKD) early on in life and as they age. AKI can also lead to CKD, and premature infants with AKI may be at very high risk for long-term kidney problems. AKI in neonates is often multifactorial and may result from prenatal, perinatal, or postnatal insults as well as any combination thereof. This review focuses on the causes of AKI, the importance of early detection, the management of AKI in neonates, and long-term sequela of AKI in neonates.     

Perinatal assessment of cerebral flow velocity wave forms in the human fetus and neonate.

The temporal relationship between changes in cerebral Doppler flow velocity wave forms, ductal patency, blood gases, and blood pressure during the transition from intrauterine to newborn life was assessed longitudinally in 16 healthy term fetuses and newborns. Doppler flow velocity wave forms were obtained from fetal cerebral arteries (anterior cerebral, internal carotid, and basilar) before birth, within 8 h after birth, and again at 24 and 48 h after birth. The resistance index was used as a measure of vascular resistance. The resistance index of the cerebral arteries studied increased significantly between the antenatal and 8-h study periods. This was followed by a significant decrease below fetal levels by the 24-h study period, with little change thereafter. We conclude that in the newborn human, as in the newborn lamb, the transition from fetal to immediate newborn life is associated with an increase in cerebral vascular resistance and thus a decrease in cerebral blood flow in response to the increase in arterial oxygenation. The subsequent decrease in the cerebral resistance index between 8 and 24 h of life cannot be explained by a loss of ductal shunting nor by associated changes in newborn blood gases or blood pressure, but may rather reflect a remodeling of the circulation due to impedance matching.     

Mechanisms of intestinal adaptation

The control of intestinal adaptation is complex and involves different mechanisms at different sites. The principal basic stimuli to adaptive growth are the presence of food in the gut lumen, endogenous secretions, and circulating hormones and peptides. Lesser factors include neural and vascular influences. Much effort has been devoted to the search for a systemic tropic factor responsible for the direct stimulation of mucosal cell proliferation. Conclusive proof is lacking, but evidence suggests that enteroglucagon or other gut-glucagon peptide fragments may be the elusive enterotropic substance. Attention has recently turned from the study of the phenomenon of intestinal adaptation itself, now well defined, to the possible intracellular mechanisms responsible for enhanced cell division. Offprint requests to: R. C. N. Williamson     

Perinatal psychiatry for the paediatrician on the postnatal ward

Maternal health and wellbeing is crucial to ensure the best outcomes for babies and children. Pregnancy and the perinatal period are particularly vulnerable times for mothers and children. Almost 1 in 5 mothers will experience some form of depression or anxiety during the perinatal period and other presentations, such as postpartum psychosis are specific to this period. Healthcare professionals, including paediatricians, whose clinical practice is devoted to the care of children often feel inadequately prepared to deal with these issues. Perinatal mental illnesses can feel daunting with anxiety about treatment impacting on the developing fetus, neonate or the breastfeeding infant. This short paper covers some common perinatal psychiatric presentations and aspects of treatment relevant for paediatricians.     

Heart rate responses to non-arousing trigeminal stimulation in infants: effects of sleep position, sleep state and postnatal age

AIMS: The aim of this study was to examine the effects of maternal smoking, sleeping position, sleep state and postnatal age on heart rate changes following non-arousing trigeminal stimulation in infants. SUBJECTS: We studied healthy term infants, 13 of whom were born to mothers who did not smoke and 11 to mothers who smoked during pregnancy. Each infant was studied using daytime polysomnography on 3 occasions: (a) 2-3 weeks, (b) 2-3 months and (c) 5-6 months after birth. Nasal air-jet stimulation was presented in both active sleep (AS) and quiet sleep (QS) when infants slept both prone and supine. RESULTS: We found no difference between infants of smoking and non-smoking mothers in any of the parameters measured. Minimum HR (MinHR) following non-arousing trigeminal stimulation was significantly lower in the supine compared to the prone sleeping position at 2-3 weeks and 2-3 months of age (p<0.05) in AS, and at all 3 ages in QS (p<0.01). MinHR was significantly lower in QS compared to AS at 2-3 months when infants slept prone and at 5-6 months when sleeping supine (p<0.01). In QS, MinHR became lower with increasing postnatal age in both sleep positions (p<0.01). In AS, there was no maturational effect. The normalized bradycardia (DeltaHR%) was significantly greater in AS than in QS at 2-3 weeks of age (p<0.05) when infants slept supine. CONCLUSION: Our study has shown that there was a decrease in heart rate (MinHR) following trigeminal stimulation in infants up to 6 months of age and this was affected by sleep position and sleep state, being larger in the supine sleeping position and the QS state.     

Perinatal cerebrovascular disease in the neonate. Parenchymal ischemic lesions in term and preterm infants.

Acute cerebrovascular injury in term and preterm infants is a cause of significant morbidity. Treatment efforts in the past have focused on attempts to prevent such injury by interceding during labor in term infants and improving neonatal care in preterm infants. Epidemiologic studies suggest that these strategies have had little impact. A new strategy--drug treatment of acute ischemic brain injury--is on the horizon. The recognition and prognostication in ischemic neonatal brain injury takes on a new importance in this light.     

Overview of intestinal adaptation and its stimulation.

Total parenteral nutrition (TPN) can be life-saving for many patients with short-bowel syndrome (SBS). However, chronic TPN administration is associated with nutritional deficiencies, septic complications, high health care costs, and life-threatening organ failure. In an effort to rehabilitate SBS patients so they may achieve enteral autonomy, investigators have attempted to stimulate the adaptive response following extensive small-bowel resection. Intestinal adaptation may include: 1) morphological changes of the residual bowel which increase the absorptive surface area; 2) functional changes that increase the absorptive capacity of individual enterocytes and colonocytes; and 3) changes in colonic production and absorption of short-chain fatty acids which improve intestinal vitality and maximize efficiency of energy and fluid absorption. Several peptides, nutrients, cytokines, and other factors promote intestinal adaptation in animals. These "growth" factors may predominantly affect one aspect of the adaptive response while having little or no effect on other physiologic or morphologic parameters. In addition, combined administration of stimulatory agents may be necessary to enhance adaptation. Dietary constituents may have profound positive and negative effects on adaptation and must be considered in developing an overall plan for treatment of the SBS patients. Only a few clinical studies have been performed to evaluate therapeutic regimens for SBS beyond standard supportive care and TPN administration. The combined administration of growth hormone, glutamine and a modified diet to over 225 adults has been shown to eliminate or decrease TPN dependence in 80% of patients receiving this therapy. Further study is required to optimize the treatment of humans with intestinal failure and to determine which patients are most likely to benefit from medical therapy. The authors conclude that the intestinal length to body weight index may be one predictive factor useful for determining which SBS patients will benefit from a trial of pharmacologic manipulation before attempting alternative, potentially more invasive therapies.     

Effects of maternal cigarette smoking and cocaine use in pregnancy on fetal response to vibroacoustic stimulation and habituation

Background: Cigarette smoking and cocaine use in pregnancy are common in the US and both are risk factors for sudden infant death syndrome (SIDS). Although the cause of SIDS is not known, one postulated mechanism involves abnormalities of arousal and arousal regulation. Cigarette smoking and cocaine use may cause deficits of arousal. Many believe arousal deficits occur prenatally. Aims: The aim of this study was to assess the effects of cigarette smoke and cocaine exposure during pregnancy on measures of fetal arousal and arousal competency: 1) the fetal response to vibroacoustic stimulation (VAS) and 2) habituation to VAS. Hypothesis: Maternal cigarette smoking and cocaine use in pregnancy are associated with altered arousal and arousal regulation in the fetus. Methods: Three groups of mother-fetal dyads were enrolled: 1) cigarette smokers (n = 54), 2) cocaine users (n = 30), and 3) controls (n = 60). One hundred eight fetuses were tested at 29-31 wk gestation, 119 at 32-35 wk, and 118 at 36+ wk. The fetal response to VAS was assessed using real-time ultrasound and a paradigm of arousal responsiveness. Responders were tested with repeated VAS to assess habituation. Also, the quality of fetal reactivity to repeated stimuli was assessed as a measure of arousal and arousal regulation competence (Behavioral Reactivity Scale). Results: The control group had a larger proportion of fetuses who were too active to initiate testing ("too active to test") (p = 0.013); the proportion of fetuses too active to test decreased with increasing gestational age. The majority of the fetuses who could be tested responded to the initial VAS, and there were no group differences. The proportion of fetuses that habituated and the rate of habituation did not differ between the groups. Behavioral reactivity did not differ between groups.

Conclusions: The original hypotheses were not confirmed. However, the chosen assessment paradigms may have lacked sensitivity. The proportion of fetuses that were "too active to test" decreased with gestational age. The control group had a larger proportion of fetuses that were "too active to test" compared with the exposure groups. We speculate that these findings indicate that prenatal exposure to these neuroteratogens may have produced an acceleration of the behavioral response to vibroacoustic stimulation.     

Physiologic significance of nitric oxide and endothelin-1 in circulatory adaptation

BACKGROUND: The purpose of the present paper was to evaluate the physiologic significance of nitric oxide (NO) and endothelin (ET)-1 in circulatory adaptation in the neonate. METHODS: The serum levels of NO metabolites (NOx; the sum of nitrites and nitrates) and the plasma level of ET-1 were determined in 14 healthy full-term infants at 0-6 h, 24 h and 5 days after birth. We measured the heart rate, the mean systemic blood pressure and the mean pulmonary arterial pressure, estimated by pulsed Doppler echocardiography, at each time point. RESULTS: The serum concentration of NOx was lowest at birth and increased with age. The plasma concentration of ET-1 was highest at birth and decreased with age. The ratio of NOx to ET-1 was inversely related to the estimated mean pulmonary arterial pressure in the early neonatal period. The ratio of NOx to ET-1 was not correlated with the systemic blood pressure. CONCLUSION: Increased NO synthesis and decreased production of ET-1 during the early neonatal period may contribute to the decrease in pulmonary arterial pressure.     

Regulation of anxiety behind quiet adaptation

The paper draws on material from a young child observation undertaken by a Chinese observer in Beijing, China. It focuses on how the observed child adapted rather quietly to his first year in nursery. He never cried, nor did he create a scene or seek special attention. Ironically, the observer was drawn to him exactly because of this lack of drama and his apparent indifference to her. This indifference aroused a strong countertransference in the observer. Closer observation revealed the possibility of equally strong feelings behind the child's various ways of coping and of defending himself against distress, anxiety and other feelings related to the transition from home to nursery. Over time, he showed more and different aspects of himself, signalling development in the relationship with the nursery staff, his peers and the observer in a significant period of transition for any toddler.     

Perinatal management of a preterm neonate affected by hyperprostaglandin E2 syndrome (HPS)

BACKGROUND: Neonates affected by hyperprostaglandin E(2) syndrome (HPS) present with severe polyuria. Both urinary losses as well as prostaglandin synthesis inhibitors may precipitate acute renal failure (ARF). AIM: Our goal was to maintain euvolaemia by replacement of urinary losses. PATIENT: Our patient was born prematurely with a family history typical of HPS. Urinary salt and water losses and PGE(2) excretion were determined in 2- to 4-h intervals. Salt and water were replaced accordingly. RESULTS: Within the first 48 h, urinary losses and PGE(2) increased continuously to 50 ml/kg/h and 374 ng/h/1.73 m(2), respectively. Following exposure to 0.05-0.5 mg/kg/d indomethacin, urinary output decreased steadily to 10-15/ml/kg/h.CONCLUSION: In euvolaemic preterm neonates with HPS and the need for excessive replacement of salt and water, inhibition of renal PGE(2) excretion with indomethacin effectively reduces polyuria and natriuresis without acutely compromising renal function.     

Effects of bathing immediately after birth on early neonatal adaptation and morbidity: A prospective randomized comparative study

OBJECTIVE: Because the risks and benefits of early bathing of newborn infants are not well established, we investigated the effects of bathing immediately after birth on rectal temperature, respiratory rate, heart rate, blood pressure, percutaneous arterial blood oxygen saturation (SpO2) and early neonatal morbidity. METHODS: The study was designed as a randomized prospective comparative study in the neonatal care unit of a university hospital. A total of 187 healthy term and near-term newborn infants, who were delivered vaginally without asphyxia, between January and December 1997 were the study subjects. We compared findings in newborns who were bathed 2-5 min after birth (n = 95) with those of a control group (n = 92) who received dry care instead. Groups were comparable with respect to gestational age, birthweight, male: female ratio, Apgar score and umbilical blood pH. Rectal temperature was measured with an electronic thermometer immediately before the intervention bathing or dry care and at 30 min and 1, 2, 3, 8 and 12 h after birth. Heart rate, respiratory rate, systolic and diastolic blood pressure and SpO2 were measured at 1, 2, 8 and 12 h after birth. The incidence of early neonatal morbidity, including hyperbilirubinemia and gastrointestinal and respiratory problems, was also compared. RESULTS: Rectal temperature changed over time postnatally in both groups (P < 0.0001, ANOVA) and there was a significant difference in rectal temperature between groups (P< 0.0001, ANOVA). Mean (+/- SEM) rectal temperature at 30 min after birth (i.e. approximately within 20 min after intervention) was significantly higher in the bathed group than in the control (dry care) group (37.30 +/- 0.06 is 37.00 +/- 0.05 degrees C, respectively; P = 0.000022). Respiratory rate, heart rate, blood pressure and the ratio of the number of infants with SpO2 90-94% and 95-100% did not differ significantly between the two groups. The incidence of early neonatal morbidity, including vomiting, acute gastric mucosal lesion, polycythemia, need for tube feeding, phototherapy and oxygen therapy, also did not differ between the two groups. CONCLUSIONS: Early bathing, minutes after birth, did not appear to adversely affect the adaptation of healthy full-term and near-term newborn infants.     

Cognitive control and conflict adaptation in youth with high-functioning autism

Background: Youth diagnosed with autism spectrum disorders (ASD) often show deficits in cognitive control processes, potentially contributing to characteristic difficulties monitoring and regulating behavior. Modification of performance following conflict can be measured by examining conflict adaptation, the adjustment of cognitive resources based on previous‐trial conflict. The electrophysiological correlates of these processes can be measured using the N2, a stimulus‐locked component of the event‐related potential (ERP). Methods: High‐density ERPs and behavioral data [i.e. response times (RTs) and error rates] were acquired while 28 youth with ASD and 36 typically developing controls completed a modified Eriksen flanker task. Results: Behaviorally, groups showed similar conflict adaptation effects; youth with ASD showed larger RT slowing on switch trials. For electrophysiology, controls demonstrated larger N2 amplitudes for incongruent (high‐conflict) trials following congruent (low‐conflict) trials than for incongruent trials following incongruent trials. Importantly, youth with ASD showed no such differences in N2 amplitude based on previous‐trial conflict. Conclusions: Lack of electrophysiological conflict adaptation effects in youth with ASD indicates irregular neural processing associated with conflict adaptation. Individuals with ASD show declines in level of conflict evaluation and adaptation. Future research is necessary to accurately characterize and understand the behavioral implications of these cognitive control deficits relative to diagnostic severity, anxiety, and personality.