Showing papers in "Developmental Psychobiology in 2005"

Multiple sensitive periods in human visual development: evidence from visually deprived children.

Abstract: Psychophysical studies of children deprived of early visual experience by dense cataracts indicate that there are multiple sensitive periods during which experience can influence visual development. We note three sensitive periods within acuity, each with different developmental time courses: the period of visually-driven normal development, the sensitive period for damage, and the sensitive period for recovery. Moreover, there are different sensitive periods for different aspects of vision. Relative to the period of visually driven normal development, the sensitive period for damage is surprisingly long for acuity, peripheral vision, and asymmetry of optokinetic nystagmus, but surprisingly short for global motion. A comparison of results from unilaterally versus bilaterally deprived children provides insights into the complex nature of interactions between the eyes during normal visual development.

Speech perception as a window for understanding plasticity and commitment in language systems of the brain.

Abstract: In this article, we provide a critical review of the literature on speech perception and phonological processing in infancy, and in populations with different experiential histories as a window to understanding how the notion of critical periods might apply to the acquisition of one part of language: the sound system. We begin by suggesting the use of the term ''optimal period'' because (a) both the onset (opening) and offset (closing) of openness to experience is variable rather than absolute and (b) phonological acquisition involves the emergence of a series of nested capabilities, each with its own sensitive period and each best explained at one of several different levels of specificity. In support, we cite evidence suggesting that to fully understand plasticity and commitment in phonological acquisition, it is necessary to consider not only the biological and experiential factors which may contribute to the onset and the offset of openness to experience but also how the sequentially developing parts of phonology constrain and direct development. In summary, we propose a nested, cascading model wherein biology, experience, and functional use each contribute. 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 233-251, 2005.

Attachment, loss, and complicated grief

Abstract: Bereavement is a highly disruptive experience that is usually followed by a painful but time-limited period of acute grief. An unfortunate minority of individuals experience prolonged and impairing complicated grief, an identifiable syndrome that differs from usual grief, major depression, and other DSM IV diagnostic entities. Underlying processes guiding symptoms are not well understood for either usual or complicated grief. We propose a provisional model of bereavement, guided by Myron Hofer's question "What exactly is lost when a loved one dies?" We integrate insights about biobehavioral regulation from Hofer's animal studies of infant separation, research on adult human attachment, and new ideas from bereavement research. In this model, death of an attachment figure produces a state of traumatic loss and symptoms of acute grief. These symptoms usually resolve following revision of the internalized representation of the deceased to incorporate the reality of the death. Failure to accomplish this integration results in the syndrome of complicated grief.

Is there a critical period for cochlear implantation in congenitally deaf children? Analyses of hearing and speech perception performance after implantation

Abstract: A range of basic and applied studies have demonstrated that during the development of the auditory system, early experimental manipulations or clini- cal interventions are generally more effective than those made later. We present a short review of these studies. We investigated this age-related plasticity in relation to the timing of cochlear implantation in deaf-from-birth children. Cochlear im- plantation is a standard intervention for providing hearing in children with severe to profound deafness. An important practical question is whether there is a critical period or cutoff age of implantation after which hearing outcomes are significantly reduced. In this article, we present data from prelingually deaf children (mostly congenitally deaf) implanted at ages ranging from 1 to 15 years. Each child was tested with auditory and speech understanding tests before implantation, and at regular intervals up to 8 years postimplantation. We measured the improvement in performance of speech understanding tests in younger implanted children and compared it with the results of those implanted at a later age. We also used a binary partitioning algorithm to divide the data systematically at all ages at implant to determine the optimum split, i.e., to determine the age at implant which best separates performance of early implanted versus later implanted children. We observed distinct age-of-implant cutoffs, and will discuss whether these really represent critical periods during development. 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 252-261, 2005.

Mother and newborn baby: mutual regulation of physiology and behavior--a selective review.

Abstract: This article reviews 30 years of work demonstrating that interactions between mother and newborn infant in the period just after birth influence the physiology and behavior of both. Close body contact of the infant with his/her mother helps regulate the newborn's temperature, energy conservation, acid-base balance, adjustment of respiration, crying, and nursing behaviors. Similarly, the baby may regulate--i.e., increase--the mother's attention to his/her needs, the initiation and maintenance of breastfeeding, and the efficiency of her energy economy through vagus activation and a surge of gastrointestinal tract hormone release resulting in better exploitation of ingested calories. The effects of some of these changes can be detected months later. Parallels to animal research and possible mechanisms are discussed.

Stability of respiratory sinus arrhythmia in children and young adolescents: a longitudinal examination.

Abstract: The stability of children's baseline respiratory sinus arrhythmia (RSA) and RSA regulation were examined longitudinally, with a 2-year lag between each of two waves of data collection. Associations between baseline RSA and RSA regulation also were examined in this study. During two laboratory sessions, 2 years apart, children were exposed to two stressors: exposure to an audiotaped conflict between two adults and a problem-solving task in which the child had to trace a star while looking into a mirror. Measures of baseline RSA and RSA regulation during the two stressors were obtained. Baseline RSA and, to a lesser extent, RSA regulation to the star-tracing task were stable over time. Furthermore, baseline RSA was associated with increased RSA suppression to the laboratory stressors. These results augment the scant longitudinal literature on psychophysiological development in elementary-school-age children and young adolescents, and support the proposition that some aspects of RSA constitute stable individual differences at the ages examined.

Species-specific differences and similarities in the behavior of hand-raised dog and wolf pups in social situations with humans

Abstract: In order to reveal early species-specific differences, we observed the behavior of dog puppies (n = 11) and wolf pups (n = 13) hand raised and intensively socialized in an identical way. The pups were studied in two object-preference tests at age 3, 4, and 5 weeks. After a short isolation, we observed the subjects' behavior in the presence of a pair of objects, one was always the subject's human foster parent (caregiver) and the other was varied; nursing bottle (3 weeks), unfamiliar adult dog (3 and 5 weeks), unfamiliar experimenter (4 and 5 weeks), and familiar conspecific age mate (4 weeks). Dogs and wolves did not differ in their general activity level during the tests. Wolf pups showed preference for the proximity of the caregiver in two of the tests; Bottle-Caregiver at the age of 3 weeks and Experimenter-Caregiver at the age of 5 weeks, while dogs showed preference to the caregiver in three tests; conspecific Pup-Caregiver and Experimenter-Caregiver at the age of 4 weeks and dog-caregiver at the age of 5. Compared to wolves, dogs tended to display more communicative signals that could potentially facilitate social interactions, such as distress vocalization, tail wagging, and gazing at the humans' face. In contrast to dog puppies, wolf pups showed aggressive behavior toward a familiar experimenter and also seemed to be more prone to avoidance. Our results demonstrate that already at this early age--despite unprecedented intensity of socialization and the comparable social (human) environment during early development--there are specific behavioral differences between wolves and dogs mostly with regard to their interactions with humans.

Maternal influences on adult stress and anxiety-like behavior in C57BL/6J and BALB/cJ mice: a cross-fostering study.

Abstract: The quality of maternal care during early life has a dramatic impact on later stress reactivity and anxiety. Two inbred mouse strains, C57BL/6J and BALB/cJ, differ in levels of maternal care, stress reactivity, and anxiety-like behavior in adulthood. However, the relative contribution of early environmental factors and genetic predisposition to differences in these strains is not known. Maternal care, plasma corticosterone levels, emotionality, and hippocampal and paraventricular nucleus (PVN) glucocorticoid receptor mRNA levels were measured in adult C57BL/6J and BALB/cJ mice. Litters were then cross-fostered and anxiety-like behavior and stress reactivity was assessed in adulthood. Significantly less maternal care and elevated stress-induced corticosterone and emotionality was observed in BALB/cJ compared to C57BL/6J mice. Yet, no strain differences were found in hippocampal or paraventricular nucleus glucocorticoid receptor mRNA levels. Cross-fostering did alter anxiety-like behavior and basal corticosterone levels, which suggests that while genetic differences account for some of the variations between these two strains early rearing conditions also contribute.

Visual cortical activity during tactile perception in the sighted and the visually deprived.

Abstract: This article reviews studies demonstrating activity in visual cortex during tactile perception in sighted participants as well as in those who have experienced visual deprivation of varying duration. This field has been very active over the last few years, with the result that a number of exciting findings have emerged, but a unifying framework is still lacking. The first section of this article deals with investigations revealing that visual cortical activity is regularly associated with the neural processing of tactile inputs in normally sighted individuals. Next, the possible reasons underlying such visual cortical recruitment are considered. The focus then shifts to the effects of visual deprivation, examining the involvement of visual cortex in sensory and language processing in the early and late blind. The final section gives an account of studies suggesting that a remarkable degree of plasticity can be observed even after quite short-lasting visual deprivation. Overall, it appears that the nature of visual cortical activity during nonvisual tasks in the sighted can be influenced by late-onset blindness and even by brief interruptions of visual input; however, the relevant neural plasticity seems to considerably more exuberant if vision is lost very early in life or was never present, which suggests that there is a critical period for the maximal expression of such plasticity.

Neurobiology of Infant Attachment

Abstract: A strong attachment to the caregiver is critical for survival in altricial species, including humans. While some behavioral aspects of attachment have been characterized, its neurobiology has only recently received attention. Using a mammalian imprinting model, we are assessing the neural circuitry that enables infant rats to attach quickly to a caregiver, thus enhancing survival in the nest. Specifically, the hyper-functioning noradrenergic locus coeruleus (LC) enables pups to learn rapid, robust preference for the caregiver. Conversely, a hypo-functional amygdala appears to prevent the infant from learning aversions to the caregiver. Adult LC and amygdala functional emergence correlates with sensitive period termination. This study suggests the neonatal brain is not an immature version of the adult brain but is uniquely designed to optimize attachment to the caregiver. Although human attachment may not rely on identical circuitry, the work reviewed here suggests a new conceptual framework in which to explore human attachments, particularly attachments to abusive caregivers.

Are there critical periods for musical development

Abstract: A critical period can be defined as a developmental window during which specific experience has a greater effect than at other times. Musical behavior involves many skills, including the basic encoding of pitch and time information, understanding scale and harmonic structure, performance, interpretation, and composition. We review studies of genetics, behavior, and brain structure and function in conjunction with the experiences of auditory deprivation and musical enrichment, and conclude that there is more supporting evidence for critical periods for basic than for more complex aspects of musical pitch acquisition. Much remains unknown about the mechanisms of interaction between genetic and experiential factors that create critical periods, but it is clear that there are multiple pathways for achieving musical expertise.

Rearing environment and hypothalamic-pituitary-adrenal regulation in young rhesus monkeys (Macaca mulatta).

Abstract: A mammal's early social environment has important regulatory effects on its behavior and physiology, and this is especially true for regulation of the hypothalamic-pituitary-adrenal (HPA) system. The present study was designed to test hypotheses that various aspects of the social environment are important influences on HPA regulation. Seven hundred seventy eight, 3- to 4-month-old rhesus monkeys were studied as part of a standardized, 24-hr biobehavioral assessment program, which included blood sampling to determine plasma cortisol concentrations. Results indicate that nursery-rearing results in a reduced cortisol set-point for the HPA system, and, for nursery-reared (NR) animals, more peer exposure during infancy is associated with a higher set-point. Age and sex differences during this period were evident but small in magnitude. These data demonstrate the important regulatory role of the social environment on nonhuman primate physiology and suggest caution in assuming that differences between individuals' cortisol levels reflect only differences in perceptions of the "stressfulness" of events.

Perceptual learning in adults with amblyopia: a reevaluation of critical periods in human vision.

Abstract: Critical periods for experience-dependent plasticity are ubiquitous. The idea that experience-dependent plasticity is closely linked with the development of sensory function is still widely held; however, there also is growing evidence for plasticity in the adult nervous system. This article reviews the notion of a critical period for the treatment of amblyopia in light of recent experimental and clinical evidence for neural plasticity. Specifically, adults with amblyopia can improve their perceptual performance via extensive practice on a challenging visual task, and this improvement may transfer to improved visual acuity. Amblyopes achieve this improvement via the mechanisms that have been shown to explain perceptual learning in the normal visual system. It is hypothesized that these same mechanisms account for at least some of the improvement that occurs in the treatment of amblyopia.

Sensitive periods in functional brain development: Problems and prospects

Abstract: The articles in this special issue discuss and describe evidence from several sensory domains relating to sensitive periods during postnatal brain development. I begin this commentary with discussion of some of the major themes that emerge from the collection of articles. Then I focus on the implications of the evidence presented in this special issue for three different perspectives on mammalian functional brain development. I conclude that the available evidence is most consistent with an ‘‘interactive specialization’’ view of functional brain development in which the closing of sensitive periods are a consequence of achieving functional specialization within a brain region or cortical area. Several authors in the collection prefer to use terms such as ‘‘sensitive period’’ or ‘‘optimum period’’ (Werker & Tees, this issue) instead of the more traditional ‘‘critical period.’’ As noted in the historical introduction by Michel and Tyler (this issue), early ethologists such as Konrad Lorenz described particular age periods during which experience must occur for it to have an effect on subsequent development and behavior. In the best known example, imprinting, it was thought that young precocial birds had to have exposure to conspecifics within hours of hatching to develop adaptive filial attachments and appropriate later mate preferences. Later work with birdsong, cats, dogs, monkeys, and language development (in humans) led to the view that critical periods were major phenomena in brain and behavioral development (for review, see Michel & Tyler, this issue); however, more in-depth studies of some of these critical periods revealed that these periods were not as critical in terms of their timing and specificity as previously supposed. For example, the critical period for imprinting in domestic chicks was shown to be extendible in time in the absence of appropriate stimulation, and the learning to be reversible under certain circumstances (for review, see Bolhuis, 1991). Evidence accrued that the plasticity underlying imprinting was ‘‘self-terminating’’ (Bateson, 1987) in a way that can be simulated by computer neural-network models that incorporate features of the known architecture of the chick forebrain (discussed later). In other words, the closing of the critical period was a natural consequence of the learning processes itself. This line of evidence, along with several others (see Michel & Tyler, this issue), has led many researchers to prefer the term ‘‘sensitive period.’’ To further clarify that neither the onset nor the offset of the period is absolute and invariant, Werker and Tees (this issue) suggest the alternative term ‘‘optimum period.’’ However, I will adopt the more commonly used ‘‘sensitive period’’ (SP) for the rest of this commentary.

Vagal regulation and emotional intensity predict children's sleep problems.

Abstract: We examined the role of children's emotional intensity and vagal functioning in predicting sleep problems in healthy elementary school-aged children. Children's dispositional emotionality was examined via parent report, and their vagal regulation was assessed via respiratory sinus arrhythmia (RSA) during a baseline and a reaction time (RT) task. Sleep problems were examined through both child reports, and home monitoring with wrist actigraphs for four consecutive nights. Increased emotional intensity was predictive of a reduced amount of sleep and increased night activity. Less apt vagal regulation, characterized by lower levels of RSA suppression to the RT task, was predictive of increased sleep problems as assessed through both subjective and actigraphy-based measures of sleep. Results indicate that children's emotionality and regulation predict unique variance in the amount and quality of children's sleep, and suggest that they may underlie, at least in part, sleep disturbances in healthy children.

Individual differences in biobehavioral organization during problem-solving in toddlers: the influence of maternal behavior, infant-mother attachment, and behavioral inhibition on the attachment-exploration balance.

Abstract: The aim of the study was to investigate the influence of maternal behavior, infant-mother attachment, and behavioral inhibition on the biobehavioral organization of toddlers during a primary non-attachment-related challenging context. In a sample of 76 toddlers, quality of attachment (secure, avoidant, ambivalent, disorganized) was assessed at 12 months. At 22 months, the subjects were observed in a challenging task according to [Matas et al. (1978) Child Development 49: 547-556], and salivary cortisol was assessed before and afterwards. Behavioral analyses included child task orientation and exploration, help seeking, proximity seeking, and attachment-exploration-balance as well as maternal supportive presence and quality of assistance. Behavioral inhibition was assessed from maternal reports. Findings from concurrent analyses indicate relations between toddler behavior and adrenocortical function and the importance of concurrent maternal support for toddler behavior. Longitudinal analyses showed that quality of attachment predicted task orientation, help seeking behavior, and the quality of the attachment-exploration-balance, while behavioral inhibition was related to approach to the task. In line with previous findings, adrenocortical activation was found only in insecure infants with high behavioral inhibition indicating the function of attachment security as a social buffer against less adaptive temperamental dispositions. Finally, within-group analyses indicated a social regulation pattern in secure toddlers while the behavior of insecure ones was additionally linked to behavioral inhibition and physiological reactivity.

Developmental changes in the functional brain responses of adolescents to images of high and low-calorie foods.

Abstract: We examined cerebral responses to visually presented food images in children and adolescents. Eight healthy normal-weight females (ages 9-15) underwent functional magnetic resonance imaging (fMRI) while viewing photographs of high- and low-calorie foods and dining utensils. In general, food images yielded significant activation within the inferior orbitofrontal cortex, hippocampus, and fusiform gyri. High calorie food images activated the left hippocampus and subgenual cingulate, and age correlated positively with activity within the orbitofrontal cortex but negatively with activity within the anterior cingulate gyrus. Low-calorie foods activated the fusiform gyrus and demonstrated age-related increases in the left superior temporal gyrus and anterior cingulate. Utensils activated the fusiform gyrus and showed age-related increases in the prefrontal cortex. Data were also compared statistically to a sample of adults exposed to the same stimulus conditions. Findings support a developmental model of adolescent maturation whereby age-related changes in cerebral functioning develop from lower-order sensory processing toward higher-order processing of stimuli via prefrontal cortical systems involved in reward anticipation, self-monitoring, and behavioral inhibition.

It's not that bad: Error introduced by oral stimulants in salivary cortisol research

Abstract: Evidence that oral stimulants can produce interference effects in salivary cortisol assays has led to advice to avoid their use However, in studies with young children, the use of these saliva-producing substances increases compliance with collection procedures Four experiments are described to examine the effects of two commonly used stimulants, SweetTarts and Koolaid Across these experiments, interference effects produced by different quantities of these stimulants (0025, 01, and 02 g) and those produced in two commonly used assays, DELFIA and EIA, were explored The impact of using cotton rolls soaked with an oral stimulant prior to saliva collection was also examined In general, oral stimulants did not affect the rank ordering of cortisol values, as the results for stimulant-treated samples were highly correlated with those of untreated samples (approximately 90 for serially collected samples and 95 for aliquots of the same saliva pool) Depending on which assay was used, however, oral stimulants increased or decreased the cortisol levels reported, with effects sizes in the small to medium range Thus, oral stimulants should not be used with only a portion of the subjects in a study, nor should researchers assay stimulant-treated samples from the same study using different assays When used sparingly, oral stimulants can be employed without compromising the quality of salivary cortisol data

Relation of neonatal iron status to individual variability in neonatal temperament.

Abstract: The relation between indices of neonatal iron status and individual differences in neonatal temperament were investigated in a sample of 148 low- income Peruvian women and their newborn infants. Using cord blood, at birth we obtained measures of neonatal ferritin, serum iron, and hemoglobin. While neonates were still in the hospital, their behavior during a structured anthropometry exami- nation was videotaped and subsequently coded on four temperament dimensions: activity level, negative emotionality, alertness, and soothability. The same dimen- sions were coded using a videotape obtained during a subsequent visit to the neonates' homes. Results indicated that lower levels of neonatal hemoglobin and serum iron were related to higher levels of negative emotionality and to lower levels of alertness and soothability. A similar pattern was found for ferritin, but only for females. For the most part, relations between neonatal iron measures and neonatal temperament were linear, operating across the full range of iron values. Our pattern of iron-temperament results could not be attributed to variation in family demo- graphics, low birth weight, gestational age, maternal dietary intake, or markers of neonatal illness and maternal diabetes. Our findings are consistent with prior research with older infants relating iron deficiency to temperament. These results support the importance of increased research on the early functional-behavioral consequences of individual differences in iron status as well as on the mechanisms that underlie such consequences. 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 141-153, 2005.

Development of human visual cortex: a balance between excitatory and inhibitory plasticity mechanisms.

Abstract: Formation of neural circuitry in the developing visual cortex is shaped by experience during the critical period. A number of mechanisms, including N-methyl-D-aspartate (NMDA) receptor activation and γ-aminobutyric acid (GABA)-mediated inhibition, are crucial in determining onset and closure of the critical period for visual plasticity. Animal models have shown that a threshold level of tonic inhibition must be reached for critical period plasticity to occur and that NMDA receptors contribute to Hebbian synaptic plasticity in the developing visual cortex. There are a number of developmental changes in these glutamatergic and GABAergic mechanisms that have been linked to plasticity; however, those changes have been shown only in animal models, and their development in the human visual cortex is not known. We have addressed this question by studying the expression of the major glutamatergic receptors, GABAA receptors, and glutamic acid decarboxylase (GAD) isoforms during the first 6 years of postnatal development of human visual cortex. There are significant changes in the expression of these proteins during postnatal development of human visual cortex. The time course of the changes is quite prolonged and suggests that it may set the pace for the prolonged critical period in human visual development. The changes also affect the nature of spatial and temporal integration in visual cortical neurons and thereby contribute to the maturation of visual functions. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 209–221, 2005.

Critical period: a history of the transition from questions of when, to what, to how.

Abstract: Although age appears to be the defining characteristic of the concept of critical period, central to its investigation is the recognition that there are specific events which must occur in a particular order for the typical development of certain characteristics to occur. A brief history of some research on critical periods reveals that our questions have shifted from those of: is there a critical period and, if so, when does it occur; to questions of what contributes to the criticality of the period; and finally to how is criticality controlled during development. Abandoning age as a defining component of development has permitted the discovery of exactly how previous and current events construct subsequent events in the process of development. The shifts in questions about critical periods mark an increasing sophistication in understanding how development can be controlled.

Methamphetamine administration during gestation impairs maternal behavior.

Abstract: Previous studies demonstrated that repeated drug exposure, such as opiates or cocaine, during the gestation period attenuates maternal behavior of rats; however, it is not known whether methamphetamine (MA), a drug whose usage has increased recently, negatively affects maternal behavior as well. Therefore, the present study tested the hypothesis that repeated subcutaneous administration of MA (5 mg/kg daily) throughout the entire gestation period alters maternal behavior. Dams (control, saline-, and MA-treated) were observed with their pups in two types of tests. In the observation test, 11 types of activities and three types of nursing positions of mothers were recorded 10 times during each 50-min session for the 22-day lactation period. A decrease in nursing and active maternal behavior was found in MA-treated mothers relative to control rats. In addition, stereotypic behavior such as rearing and sniffing was increased in MA- as well as in saline-treated mothers relative to controls. All mothers, regardless of the treatment, displayed significantly less maternal behavior and more nonmaternal activities as postpartum time progressed. In the retrieval test, mothers also were tested for pup retrieval from postpartum Days 1 through 12. MA-treated mothers were slower in retrieving the first pup, returning the first pup into the nest, and returning all pups into the nest relative to controls or saline-treated mothers. Interestingly, the latency to return all pups to the nest was longer in saline-treated mothers relative to controls. In conclusion, the present study demonstrates a novel finding that MA administered during the gestation period has a negative effect on maternal behavior.

Repeated MDMA (“Ecstasy”) exposure in adolescent male rats alters temperature regulation, spontaneous motor activity, attention, and serotonin transporter binding

Abstract: Previous research in our laboratory found that repeated exposure of adolescent rats to 3,4-methylenedioxymethamphetamine (MDMA) impaired working memory and reduced anxiety. The present experiment extended these findings by investigating the physiological, behavioral, and neurotoxic effects of a modified MDMA treatment regimen. Male Sprague-Dawley rats received 5 mg/kg of MDMA hourly for a period of 4 hr on every fifth day from postnatal day 35-60. Acute effects of the MDMA treatment included hypothermia, serotonin syndrome behavior, and ejaculation. Body weight gain was attenuated by repeated drug administration. The animals completed anxiety and working memory tests beginning 4 days after the final MDMA dose. MDMA altered habituation to the open-field, increased locomotor activity in the elevated plus-maze, decreased attention in the novel object-recognition test, and reduced serotonin transporter binding in the neocortex. These results indicate that repeated exposure to a relatively moderate MDMA dose during adolescence produces later changes in behavior and neurochemistry.

Cardiac reactivity is associated with changes in negative emotion in 24-month-olds.

Abstract: Despite the call for multilevel observation of negative affect, including multiple physiological systems, too little empirical research has been conducted in infants and young children, and physiology-affect associations are not consistently reported. We examined changes in heart rate, respiratory sinus arrhythmia, and preejection period in 24-month-olds across four increasingly challenging, emotion-eliciting tasks. We predicted that changes in cardiac reactivity would be systematically related to changes in negative affect. Results largely support the predictions with one important exception. With increasing distress across the tasks, HR increased and RSA decreased. However, no significant changes in PEP were observed. HR was associated with negative affect during all tasks, and changes in HR were related to changes in negative affect. PEP and negative affect were associated, but only marginally so. Within-subject analyses confirmed the predicted associations. Finally, the associations between physiology and negative affect were different for boys and girls. We discuss these results in the context of implications for future research on cardiac-affect associations in young children.

Development of somatosensory-motor integration: an event-related analysis of infant posture in the first year of independent walking.

Abstract: The ability to integrate sensation with action is considered an important factor underlying the development of upright stance and locomotion. While many have studied sensory influences on posture, the nature of these influences and how they change with development have yet to be thoroughly characterized in infancy. Six infants were examined from 1 month prior to walk onset until 9 months of independent walking experience while standing quietly and touching either a static or a dynamic surface. Five adults were examined performing an analogous task. An event-related, time-frequency analysis was used to assess the relationship between postural sway and the motion of the somatosensory stimulus. Phase consistency between sway and stimulus was observed for both adults and infants, and with walking experience the infants increased their phase consistency rather than changing aspects of response amplitude. It is concluded that walking experience provides opportunities for an active tuning of sensorimotor relations for adequate estimation of body position in space and thus facilitates refined control over temporal aspects of postural sway.

Handedness and specific language impairment: a study of 6-year-old twins.

Abstract: Handedness and language skills were assessed in 196 same-sex twin pairs (101 MZ and 95 DZ), who were selected from an epidemiological study of twins, so that children with risk of language impairment were over-represented. When assessed at 6 years of age, 83 children met criteria for specific language impairment (SLI), 32 had general developmental (GD) delay, and the remaining 277 were typically-developing (TD). Hand preference (HP) assessed by inventory did not distinguish SLI, TD, or GD groups. The quantification of hand preference (QHP) measure, which measures persistence of a HP when reaching across the midline, did show weaker HP in those with SLI compared to the other two groups. It is suggested that the QHP measure assesses developmental aspects of manual lateralization, and is sensitive to neurodevelopmental immaturity in SLI. Furthermore, genetic analysis showed that the QHP measure, unlike the handedness inventory, was significantly heritable.

Variability in “spontaneous” maternal behavior is associated with anxiety‐like behavior and affiliation in Naïve juvenile and adult female prairie voles (Microtus ochrogaster)

Abstract: Juvenile female prairie voles (Microtus ochrogaster) are spontaneously maternal, while virgin adult females show significant variability in their response to first pup exposure, ranging from infanticidal to full maternal behavior. In the present study, we investigated whether differences in anxiety-like behavior and affiliation are associated with juvenile-adult and adult individual differences in the response to pups. Forty juvenile (19-20 days) and 42 adult (60-90 days) female prairie voles were exposed to pups for the first time and tested for maternal behavior, anxiety-like behavior (elevated plus maze, open field), and affiliation toward age-matched, same sex conspecifics. Juveniles displayed less anxiety-like behavior, were more affiliative to unfamiliar conspecifics, and interacted with pups more positively than adults. Adults that displayed maternal behavior spent less time immobile, made more crosses through the center of the open field arena, and were more affiliative than adults that attacked the pups. This suggests that lower locomotion or exploration in a novel environment and poor affiliative behavior are negatively associated with maternal responsiveness in female prairie voles.

Social withdrawal behaviors in nonhuman primates and changes in neuroendocrine and monoamine concentrations during a separation paradigm

Abstract: This study investigated relationships between withdrawal behaviors in rhesus macaques and changes in monoamine metabolite and endocrine concentrations during repeated psychosocial stress. Rhesus monkeys (N = 71) experienced maternal separation in which four separations took place during four consecutive weeks. Behavioral observations were made, as well as plasma concentrations of cortisol and cerebrospinal fluid concentrations of the serotonin, dopamine, and norepinephrine metabolites were obtained. Animals were assigned to high, moderate, and low withdrawal groups, defined using baseline durations of withdrawal behaviors. Highly withdrawn animals showed less reduction than nonwithdrawn animals in serotonin metabolite concentrations over repeated separations. Highly withdrawn macaques also failed to significantly reduce cortisol concentrations across separation weeks. More adaptation in central serotonin functioning and cortisol concentrations was seen in nonwithdrawn primates than in highly withdrawn primates; these findings have implications for increased risk of developing anxiety disorders in highly inhibited children.

Nongenomic inheritance of emotional reactivity in Japanese quail

Abstract: Avian scientific literature includes few reports on the influence of characteristics of mothers on the behavior of their offspring. By comparing young domestic Japanese quail raised by adoptive mothers with high levels of general emotional reactivity (E+ mothers) to young raised by adoptive mothers with low levels of general emotional reactivity (E- mothers), we evaluated the influence of characteristics of mothers on the behavioral development of their offspring. Our results revealed that general emotional reactivity was higher in young raised by E+ mothers than in young raised by E- mothers. These differences were significant in the presence of mothers as well as after separation from them, suggesting direct as well as long-term maternal influence. Young raised by E+ mothers also presented delayed increases in weight.

Effect of flavored beverage crystals on salivary cortisol enzyme-immunoreactive assay measurements.

Abstract: We examined the effects of using flavored drink crystals as a salivary stimulant on salivary cortisol values. The effects of both amount and method of flavored crystal administration on cortisol values were evaluated using a high sensitivity enzyme immunoassay (EIA) kit to measure cortisol. Repeated saliva sampling, one sample without the drink crystal stimulant, followed immediately by a second sample using the drink crystal stimulant, allowed direct analysis of the effect of the stimulant on cortisol values. Repeated sampling, with the stimulant used when obtaining both the first and second samples, allowed analysis of the repeatability of cortisol measurements using the drink crystals. The results suggest that the use of drink mix crystals as an oral stimulant causes a small increase in measured cortisol values, as well as an increase in the variability of these values. The results also suggest that the effect of drink crystals is sufficiently regular so that it will not distort either within or between subject comparisons as long as there is consistency in use or non-use of the stimulant.