Infant Behavioral Development Research Articles

The energetics of lactation and the return to fecundity in wild chimpanzees

Parental provisioning of offspring is an intensive energetic investment that is expected to compromise future offspring production. This trade-off is particularly salient for mammals in which mothers bear the exclusive burden of lactation and draw from their own energy reserves to provision offspring. The degree to which lactation impacts future reproductive ability should vary not only by the absolute cost of milk production but also by the ability of individual mothers to afford it. Few studies have been able to quantify the costs of lactation or how they affect reproductive rates. Here, we examine the metabolic load of lactation in chimpanzees, a species with intensive parental investment and extremely slow reproductive rates. We used urinary C-peptide of insulin to trace changes in energetic condition in 17 wild, unprovisioned chimpanzee mothers in Kibale National Park, Uganda. C-peptide levels of nursing mothers were depressed for six months postpartum, thereafter showing a net increase through the second year. These changes are consistent with milestones of infant physical and behavioral development. Mothers inhabiting lower quality foraging areas experienced a higher metabolic load of lactation, as indicated by lower C-peptide profiles than mothers in food-rich areas. Ovarian activity was closely correlated with energetic condition. Cycling resumed only after a sustained period of energy gain, suggesting that the slow reproductive pattern in wild chimpanzees results not only from the direct expense of milk production but also from the long period that mothers require to recover their physical condition in a food-limited environment. Key wor ds: C-peptide of insulin, energy balance, interbirth inter vals, lactation, reproduction, weaning. [Behav Ecol]

Screening for Depression and Help-Seeking in Postpartum Women During Well-Baby Pediatric Visits: An Integrated Review

PurposeThe purposes of this integrated review are to examine the literature on screening for depression and help-seeking behaviors by postpartum women during pediatric well-baby visits; to identify gaps in the literature relating to depression and help-seeking behaviors; and to discuss implications for practice and future research. MethodAn extensive search of primary source documents was conducted in Academic Search Premier, CINAHL, MEDLINE, Mental Measurements Yearbook, PsycINFO, PsycARTICLES, and Women's Studies International using the key words postpartum, postpartum depression (PPD), help seeking, and pediatric setting or pediatrician. Thirty-five articles relevant to help seeking, PPD, and screening in the pediatric setting were included in this review. Research studies included both quantitative and qualitative articles. ResultsPPD affects 10% to 15% of all women after birth. Postpartum women generally do not seek help for depression. Untreated PPD has significant adverse affects on parenting, maternal bonding, and the infant's emotional and behavioral development. Interaction with the woman's obstetric provider ends shortly after the baby's birth. However, interactions with the pediatric office are initiated and continue throughout the infant's first two years of life. DiscussionEarly recognition of PPD and appropriate treatment are imperative for positive maternal-infant outcomes. A majority of women do not seek help for depression from any source. Because mothers have routine interactions with pediatric office staff during the first few years after giving birth, pediatric nurse practitioners and pediatricians have the perfect opportunity to screen and educate women regarding symptoms, treatment, and available resources for PPD.

Pre- and Postnatal PCB Concentrations and Child Behavior at Age 45 Months

ISEE-0883 Background and Objective: While data have been published concerning children’s cognitive development in relation to developmental polychlorinated biphenyl (PCB) exposure, less is known about the impact of PCBs on infant and child behavioral development. The current study assesses child behavior through maternal report using the Child Behavior Checklist (CBCL) in a cohort of families living in eastern Slovakia environmentally-exposed to PCBs. Methods: Pregnant women were enrolled into the study at the time they came to the local hospital to deliver. Maternal and cord blood samples were collected for PCB determination, as well as 6-, 16-, and 45-month samples from the infant/child. A “total” PCB measure was calculated as the sum of six congeners (118, 138, 153, 156+171, 170, 180) for maternal concentrations, and as the sum of four congeners (138, 153, 170, 180) for cord and infant/child concentrations. After delivery, women completed questionnaires concerning lifestyle and sociodemographic characteristics, and were administered the Raven’s Progressive Matrices. In addition, the Home Observation for Measurement of Environment Inventory (HOME) was completed at the 16-month follow-up. At the child’s 45-month follow-up visit, mothers completed the Child Behavior Checklist 1.5-5. Subscale scores were calculated for the seven syndromes (emotionally reactive, anxious/depressed, etc.) as well as for internalizing and externalizing behaviors. The association between (natural log) total PCB concentrations and the various CBCL scores was estimated and tested using linear regression. Results: Complete data were available for 398 children. After adjustment for HOME Scores, maternal Raven score, and Romani ethnicity, neither maternal nor postnatal (natural log) total PCB concentrations were associated with any of the seven syndrome scores, or internalizing or externalizing behavior scores. Conclusion: Data from this cohort do not provide support for the hypothesis that developmental PCB exposure plays a role in early childhood behavioral development.

Psychomotor development and behavior in iron-deficient anemic infants.

Research has shown an association between iron deficiency anemia and adverse effects on behavior and psychomotor development in infants and children. The exact mechanisms behind these associations are not fully understood. Additional research is necessary.

Mother–infant interactions in free-ranging rhesus macaques: Relationships between physiological and behavioral variables

Studies of mother–infant relationships in nonhuman primates have increasingly attempted to understand the neuroendocrine bases of interindividual variation in mothering styles and the mechanisms through which early exposure to variable mothering styles affects infant behavioral development. In this study of free-ranging rhesus macaques on Cayo Santiago, Puerto Rico, we aimed to: 1) compare lactating and nonlactating females to investigate whether lactation is associated with changes in plasma cortisol, prolactin and oxytocin, as well as changes in CSF levels of serotonin and dopamine metabolites (5-HIAA and HVA); 2) examine the extent to which interindividual variation in maternal physiology is associated with variation in maternal behavior; 3) examine the extent to which interindividual variation in infant physiology and behavior is accounted for by variation in maternal physiology and behavior. Lactating females had higher plasma concentrations of cortisol, prolactin, and oxytocin but lower CSF concentrations of HVA than nonlactating females. Variation in maternal rejection behavior was positively correlated with variation in maternal plasma cortisol levels and in CSF 5-HIAA levels while variation in the time spent nursing and grooming was associated with maternal plasma oxytocin levels. Infants who were protected more by their mothers had higher cortisol levels than those who were protected less, while infants who were rejected more had lower CSF 5-HIAA than infants who were rejected less. Since exposure to high levels of maternal protectiveness and rejection is known to affect the offspring's behavior and responsiveness to the environment later in life, our results are consistent with the hypothesis that these effects are mediated by long-term changes in the activity of the offspring's HPA axis and brain serotonergic system.

Perspectives from the symposium: The Role of Nutrition in Infant and Toddler Brain and Behavioral Development

This symposium examined current trends in neuroscience and developmental psychology as they apply to assessing the effects of nutrients on brain and behavioral development of 0–6-year-olds. Although the spectrum of nutrients with brain effects has not changed much in the last 25 years, there has been an explosion in new knowledge about the genetics, structure and function of the brain. This has helped to link the brain mechanistic pathway by which these nutrients act with cognitive functions. A clear example of this is linking of brain structural changes due to hypoglycemia versus hyperglycemia with cognitive functions by using magnetic resonance imaging (MRI) to assess changes in brain-region volumes in combination with cognitive test of intelligence, memory and processing speed. Another example is the use of event-related potential (ERP) studies to show that infants of diabetic mothers have impairments in memory from birth through 8 months of age that are consistent with alterations in mechanistic pathways of memory observed in animal models of perinatal iron deficiency. However, gaps remain in the understanding of how nutrients and neurotrophic factors interact with each other in optimizing brain development and function.

Weaning Age, Infant Care, and Behavioral Development in Trachypithecus leucocephalus

Primate infants are born in an altricial state and rely on the care of their parents for a relatively long period of time. Parental investment is critical to offspring survival and thus to the reproductive success of the parent as well. However, mothers and infants may experience a conflict of interest, in that infants may benefit by receiving prolonged maternal care but mothers may curtail such care in a tradeoff between investment in current versus future offspring. Documenting life history characteristics, such as age at weaning, is important not only for understanding the conflicts of interest and tradeoffs; such information can also provide insights about female reproductive rates and be valuable for conservation efforts. Little is known about the life history of white-headed langurs (Trachypithecus leucocephalus), despite their endangered status. We were the first to investigate mother-infant relationships and infant behavioral development in the species. We studied 3 wild mother-infant pairs throughout infancy. We used data from >460 h of focal subject sampling to calculate the proportion of time individuals spent in different behavioral states and the frequency of instantaneous events, such as maternal rejection. White-headed langur infants depended on their mothers for 19–21 mo, at which time they were weaned. Maternal rejection facilitated infant independence in the early stages of infant development, and mothers stopped investing in their infants when they resumed estrus. The weaning age of the wild white-headed langurs we studied was dramatically longer than that of captives, possibly as a result of the nutritional differences between wild and captive populations. Weaning age was also longer than for most other Asian colobines, and may be attributable to the degradation and fragmentation of their natural habitat.

Neonatal Dietary Cholesterol and Alleles of Cholesterol 7-α Hydroxylase Affect Piglet Cerebrum Weight, Cholesterol Concentration, and Behavior ,

This experiment was designed to test the effect of polymorphism in the cholesterol 7-α hydroxylase (CYP7) gene locus and dietary cholesterol (C) on cerebrum C in neonatal pigs fed sow’s milk formulas. Thirty-six pigs (18 male and 18 female) genetically selected for high (HG) or low (LG) plasma total C were weaned at 24–36 h after birth and assigned in a 2 × 2 × 2 factorial arrangement of treatments with 2 diets (0 or 0.5% C), 2 sexes, and 2 genotypes (HG and LG). Individually housed pigs consumed diets ad libitum for 42 d. Open-field behavior was tested at wk 2 and 4. All pigs were killed at 42 d of age, the cerebrum was weighed, and C content and concentration measured. All data were analyzed by general linear model ANOVA. Cerebrum weight was greater in HG than LG pigs (P < 0.03) but was not affected by diet or sex. Pigs fed C tended to have a higher cerebrum C concentration than those deprived (P = 0.12). At 2 wk, LG pigs explored a novel open-field environment less often (P < 0.001) than did HG pigs. At 4 wk, some LG pigs explored the open field but fewer (P < 0.001) vs. HG pigs retreated back to the safe area. There were no genotype x diet, genotype x sex, or diet x sex interactions affecting cerebrum weight, or C content or concentration. Polymorphism in the CYP7 gene locus affected cerebrum weight and behavior and dietary C tended to increase cerebrum C concentration in neonatal pigs. These findings in neonatal pigs have considerable potential importance in human infant nutrition and behavioral development.

Perspectives from the symposium: The Role of Nutrition in Infant and Toddler Brain and Behavioral Development

Perspectives from the symposium: The Role of Nutrition in Infant and Toddler Brain and Behavioral Development

Maternal behavior, infant development, and the question of developmental resources

The natural development of maternal and infant behavior occurs in a dyad characterized by synchrony and reciprocal interactions. Major concepts used to describe and analyze this synchrony were reviewed. It was concluded that the dyad undergoes a developmental progression in which each part of the dyad is both a developing organism and a reliably changing milieu forming part of the extended inheritance of the other. The reliability of inherited resources is rooted in interactions essential to life, such as those used to transfer metabolic needs to dependent offspring; to stimulation (incidentally but necessarily) associated with life-supporting mechanisms; and to perceptual, motor, or learning mechanisms used to extract specific resources from the available milieu. The diverse resources in extended inheritance contribute to the construction of new traits through opportunistic shaping or regulating interactions among them that are unrestricted by their function at earlier stages.

Maternal behavior and maternal stress are associated with infant behavioral development in macaques

The simultaneous effects of naturally occurring individual differences in maternal care and maternal peripartum stress on infant development have been sparsely reported in nonhuman primates. In this work, we used a comparative approach to assess how changes in peripartum maternal excreted cortisol levels and the quality of mother-infant interactions correlate with infant behavioral development in group-living rhesus and Japanese macaques. We tested the hypothesis that peripartum maternal stress was associated with infant behavioral characteristics during development. Due to the difference in mothering style between the two species, we provided separated analyses for two groups. A sample of mother-infant pairs (Japanese macaques, N = 14; rhesus macaques, N = 10) was observed during the first 3 months of the infant's life. Follow-up observations (at 5, 7, and 9 months of age) were collected for the infants. Maternal cortisol levels were measured during the peripartum period. We found preliminary evidence that maternal peripartum stress and differences in key components of maternal behavior are associated with infant behavior throughout the developmental phase. We also provided a working hypothesis regarding maternal behavior and maternal stress as factors playing unique roles in different components of infant behavioral development.

Examining the role of endogenous opioids in learned odor-stroke associations in infant rats.

Maternal touch profoundly regulates infant neural and behavioral development, and supports learned odor associations necessary for infant attachment. Endogenous opioids are well characterized to mediate the calming and analgesic properties of maternal touch; yet their role in learned odor-touch associations is unknown. We administered naltrexone, an opioid receptor antagonist, before or immediately following classical conditioning with peppermint odor and tactile stimulation (stroking) in rat neonates. Results indicate odor-stroke conditioning produces odor preferences facilitated by endogenous opioids during acquisition and memory consolidation. These results provide additional evidence for the modulatory role of opioids in neonate learning and memory. Disturbances to this system may alter the impact of touch on infant development, particularly in the realm of learning necessary for attachment.

Mother-child linguistic interactions and behavioral development: A multidimensional observational.

Child development is a crucial field for understanding the origins and functions of processes related complex human behavior. However, in spite of the fact that development, although not due the passage of time per se, takes place along time, behavior analysis has paid little attention longitudinal studies of behavior development in infants and children (Bijou, 1989; Ribes, 1996). Behavior analytic efforts have rather been directed transversal experimental or applied studies, in which particular settings and behaviors have been selected out of the stream of development as a continuous and irreversible process (Gewirtz & Pelaez-Nogueras, 1991; Poulson & Kymissis, 1996; Rosales-Ruiz & Baer, 1996). In most developmental studies, language behavior has been normally considered a special area in its own right, apart of the rest of behavioral processes or phenomena involved in development. Other putative areas of development include affection, cognition, attention and perception, motor behavior, and social and moral behavior (Bijou, 1975; Farah & Kosslyn, 1982; Malcuitt, Pomerleau & Lamarre, 1988; Parke, 1989; Riegler & Baer, 1989; Zimmerman & Whitehurst, 1979). Behavior analytic research on language development has rather focused on two aspects: a) training-acquisition procedures related some of the responses classes proposed by Skinner (1957), such as manding and tacting (Partington, Sundberg, Newhouse, & Spengler, 1994; Ribes, Gomar-Ruiz, & Rivas, 1975; Simic & Bucher, 1980; Yamamoto & Mochizuki, 1988), and b) the identification and demonstration of reinforcement control over so-called generalized operant classes, such as imitation, grammatical or syntactic responses, instruction following, and verbal-non verbal correspondence (Deacon & Konarski, 1987; Garcfa, Guess, & Byrnes, 1973; Hart & Risley, 1980; Hester & Hendrickson, 1977; Ribes, 1986; Stokes, Osner, & Guevremont, 1987), all classes which are assumed underlie the emergence of new, non-directly trained linguistic responses. There are few studies focusing on the actual behavioral interactions of the child (as a language leamer) and the mother, a caregiver, or a trained teacher (Bijou, Umbreit, Guezzi & Chao, 1986; Moerk, 1983, 1990; Rondal, 1981; Snow, 1989), and only some of them have dealt with language acquisition and development from its beginnings. These studies show the decisive effect of the mother in promoting the acquisition and extension of speech in children. On the one hand, Rondal studied how the adaptations of maternal language child language in terms of prosody, phonology, lexicon, semantic content and pragmatic aspects of speech, facilitated the acquisition of speech by the child. On the other hand, Moerk (1983, 1990) analyzed how maternal speech and feedback temporally and structurally adapt themselves the child's speech, in such a way that it is possible identify systematic teaching strategies related the acquisition and extension of locutionary and syntactic features of speech by the child. Although these studies show the importance of the mother's behavior in the child's acquisition and development of language, they do not take into account the intermingling of language development with the overall development and socialization that necessarily take place as an effect of mother-child linguistic interactions. The articulation of development through language Wittgenstein (1953) advanced the notion that to imagine a language means imagine a form of (p.19). Language as a form of life is a notion that involves individual practices with objects and people as an integrated totality, the extent that language is present and articulates every kind of imaginable social activity. The human environment, in the form of culture and social relations, is built through language, and no human behavioral practice could be understood apart from language. …

The relationship between physical growth and a newborn reflex

Young infants both grow at a very rapid rate and show dramatic changes in body composition. The behavioral consequences of somatic growth have been little explored. Here we report three studies on the relationship between body-build changes and a newborn reflex, stepping. Study 1 compared the number of steps and several body-build measures in 40 infants seen at 2, 4, and 6 weeks. At each age, overall arousal was the best predictor of steps. At 4 weeks, however, those infants who gained weight and became “chubby” most rapidly stepped less. Infants gained weight and added fat at the most rapid rate between 2 and 4 weeks. In Study 2, we manipulated leg mass by adding small weights to the legs. Infants stepped less and with weaker flexion movements when the legs were weighted. In Study 3, we reduced the effects of leg mass by submerging infants’ legs in water. Stepping rate increased and joint flexions were greater. We proposed that muscle strength development may not be synchronous with mass increase and that peripheral as well as central nervous system factors contribute to infant behavioral development. The disappearance of stepping is better explained by asynchronous physical growth than by previous hypotheses.

Investigation of the Role of Postnatal Testosterone in the Expression of Sex Differences in Behavior in Infant Rhesus Macaques (Macaca mulatta)

In several primate species, males have been shown to exhibit a surge in circulating testosterone during the early postnatal period. This surge has been postulated to play a role in the development of sex differences in behavior. In this study, the role of postnatal testosterone in infant behavioral development was investigated in socially living rhesus macaques. Seven male infants were treated with a GnRH agonist, avorelin, from the first week of life onwards. Ten female infants were exposed to testosterone by implantation of capsules containing testosterone. The behavioral development of these and control infants was recorded from birth to 6 months of age. The sexually dimorphic patterns of play and mounting were not affected by manipulation of postnatal testosterone in either male or female infants. Similarly, most mother–infant interactions were not affected by the hormonal manipulation of infants. Mothers of testosterone-treated females were found to take more responsibility for moving into and out of arm's reach of their infants than mothers of some other groups of infants; however, this measure did not normally differ between mothers of male and female infants. Manipulation of the postnatal testosterone surge does significantly affect penile growth and development, but does not affect the expression of infant sex differences in behavior nor greatly affect the development of the mother–infant relationship in rhesus macaques.

Perceiving the causes of infant crying

Six week old infants who fussed and cried for 3 or more hrs per day (persistent criers), evening criers, and moderate criers were assessed using researcher and maternal measures of infant, maternal and family characteristics at 6 weeks, 5 months and 15 months of infant age. Convergent evidence of stable individual differences in negative behavior was found between 6 weeks – 5 months and 5 – 15 months of age. Objectively hard-to-soothe infants, particularly, were distinguished on a range of researcher and maternal measures. Between 6 weeks and 15 months, infant negative behavior was not a stable characteristic, although mothers continued to rate the same infants as fussy/difficult. In multiple regression analyses, infant negative behavior at 6 weeks did not predict maternal or researcher measures of infant negativity, temperament, behavior problems or cognition at 15 months. Maternal and family variables mediated the development of infant negative behavior.

Perinatal bupivacaine and infant behavior in rhesus monkeys.

To assess the effect of perinatal epidural bupivacaine analgesia on infant behavioral development, bupivacaine (1.2 mg/kg) was administered to term-pregnant rhesus monkeys (treated, n = 11, procedural controls, n = 8) and infant behavior was evaluated for 1 year using a test battery including infant neurobehavioral tests, observation of spontaneous behavior, and structured cognitive testing. No adverse effects of bupivacaine were detected for neonatal neurobehavior, early cognitive abilities, or performance of cognitive tasks by older infants. Bupivacaine infants directed more, shorter fixations at visual stimuli during visual novelty preference testing. Observation of behavior maturation patterns showed that the increase in manipulatory activity that normally occurs at 2 months of age was delayed in bupivacaine infants, and the increase in motor disturbance behaviors that normally occurs at 10 months of age was prolonged. These results are interpreted in terms of life-history and brain maturation landmarks that appear at these ages. The data suggest that epidural bupivacaine does not cause neonatal abnormalities or specific cognitive deficits but can alter the normal course of behavioral development.

Stability and outcome of persistent infant crying

Six week old infants who fussed and cried for 3 or more hrs per day (persistent criers), evening criers, and moderate criers were assessed using researcher and maternal measures of infant, maternal and family characteristics at 6 weeks, 5 months and 15 months of infant age. Convergent evidence of stable individual differences in negative behavior was found between 6 weeks – 5 months and 5 – 15 months of age. Objectively hard-to-soothe infants, particularly, were distinguished on a range of researcher and maternal measures. Between 6 weeks and 15 months, infant negative behavior was not a stable characteristic, although mothers continued to rate the same infants as fussy/difficult. In multiple regression analyses, infant negative behavior at 6 weeks did not predict maternal or researcher measures of infant negativity, temperament, behavior problems or cognition at 15 months. Maternal and family variables mediated the development of infant negative behavior.

A Reconceptualization of the Effects of Undernutrition on Children's Biological, Psychosocial, and Behavioral Development and commentaries

A Reconceptualization of the Effects of Undernutrition on Children's Biological, Psychosocial, and Behavioral Development and commentaries

The relationship between physical growth and a newborn reflex

Abstract Young infants both grow at a very rapid rate and show dramatic changes in body composition. The behavioral consequences of somatic growth have been little explored. Here we report three studies on the relationship between body-build changes and a newborn reflex, stepping. Study 1 compared the number of steps and several body-build measures in 40 infants seen at 2, 4, and 6 weeks. At each age, overall arousal was the best predictor of steps. At 4 weeks, however, those infants who gained weight and became “chubby” most rapidly stepped less. Infants gained weight and added fat at the most rapid rate between 2 and 4 weeks. In Study 2, we manipulated leg mass by adding small weights to the legs. Infants stepped less and with weaker flexion movements when the legs were weighted. In Study 3, we reduced the effects of leg mass by submerging infants’ legs in water. Stepping rate increased and joint flexions were greater. We proposed that muscle strength development may not be synchronous with mass increase and that peripheral as well as central nervous system factors contribute to infant behavioral development. The disappearance of stepping is better explained by asynchronous physical growth than by previous hypotheses.