Showing papers in "Developmental Psychobiology in 2012"

Longitudinal stability and developmental properties of salivary cortisol levels and circadian rhythms from childhood to adolescence.

Abstract: This study aimed to (1) identify a stable, trait-like component to cortisol and its circadian rhythm, and (2) investigate individual differences in developmental trajectories of HPA-axis maturation. Multiple salivary cortisol samples were collected longitudinally across four assessments from age 9 (3rd grade) through age 15 (9th grade) in a community sample of children (N = 357). Sophisticated statistical models examined cortisol levels and its rhythm over time; effects of age, puberty and gender were primarily considered. In addition to situation-specific and stable short-term or epoch-specific cortisol components, there is a stable, trait-like component of cortisol levels and circadian rhythm across multiple years covering the transition from childhood into adolescence. Youth had higher cortisol and flatter circadian rhythms as they got older and more physically developed. Girls had higher cortisol, stronger circadian rhythms, and greater developmental influences across adolescence. Distinguishing a stable, trait-like component of cortisol level and its circadian rhythm provides the empirical foundation for investigating putative mechanisms underlying individual differences in HPA functioning. The findings also provide important descriptive information about maturational processes influencing HPA-axis development.

The mirror neuron system and treatment of stroke.

Abstract: Mirror neurons discharge during the execution of ecological goal-directed manual and oral actions, as well as during the observation of the same actions done by other individuals. These neurons were first identified in the ventral premotor cortex (PMv; area F5) and later on in the inferior parietal lobule (areas PF and PFG) of monkey brain, constituting a “mirror neuron” system. Several pieces of experimental data suggest that a mirror neuron system devoted to hand, mouth, and foot actions might also be present in humans. In the present paper, we review the experimental evidence on the role of the mirror neuron system in action understanding and imitation, both in hand motor function and speech. Based on the features of the mirror neuron system and its role in action understanding and imitation, we discuss the use of action observation and imitation as an approach for systematic training in the rehabilitation of patients with motor impairment of the upper limb and aphasia following stroke. We present the results of some preliminary studies to test this concept, and a discussion of network models as a measure of neurobiological change. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 54:293-310, 2012.

Neurodevelopmental MRI brain templates for children from 2 weeks to 4 years of age

Abstract: Spatial normalization and segmentation of pediatric brain magnetic resonance images (MRI) data with adult templates may impose biases and limitations in pediatric neuroimaging work. To remedy this issue, we created a single database made up of a series of pediatric, age-specific MRI average brain templates. These average, age-specific templates were constructed from brain scans of individual children obtained from two sources: (1) the NIH MRI Study of Normal Brain Development and (2) MRIs from University of South Carolina's McCausland Brain Imaging Center. Participants included young children enrolled at ages ranging from 8 days through 4.3 years of age. A total of 13 age group cohorts spanning the developmental progression from birth through 4.3 years of age were used to construct age-specific MRI brain templates (2 weeks, 3, 4.5, 6, 7.5, 9, 12, 15, 18 months, 2, 2.5, 3, 4 years). Widely used processing programs (FSL, SPM, and ANTS) extracted the brain and constructed average templates separately for 1.5T and 3T MRI volumes. The resulting age-specific, average templates showed clear changes in head and brain size across ages and between males and females, as well as changes in regional brain structural characteristics (e.g., myelin development). This average brain template database is available via our website (http://jerlab.psych.sc.edu/neurodevelopmentalmridatabase) for use by other researchers. Use of these age-specific, average pediatric brain templates by the research community will enhance our ability to gain a clearer understanding of the early postnatal development of the human brain in health and in disease.

BDNF control of adult SVZ neurogenesis

Abstract: The sensory processing of odorants is a dynamic process that requires plasticity at multiple levels. In the olfactory bulb (OB), inhibitory interneurons undergo lifelong replacement through a process known as adult neurogenesis. These newly born cells are incorporated in a learning-dependent fashion, a process which has led some to suggest this as a primary mechanism through which the OB retains a high degree of plasticity throughout life. A continued focus of researchers in this field has been to understand the molecular mechanisms controlling adult subventricular zone (SVZ) neurogenesis and the innate functional role of these cells. Brain-derived neurotrophic factor (BDNF) has been identified as a strong candidate molecule regulating adult OB neurogenesis. We review what is known regarding the functional role of newly-born cells, highlight the role of BDNF in this process, and describe preliminary findings from our lab implicating BDNF in the process of selecting of newly born cells for survival.

Human Amygdala Development in the Absence of Species-Expected Caregiving

Abstract: In altricial species, like the human, caregiver presence is necessary for typical emotional development. Children who have been raised in institutional care early in life experience caregiver deprivation and are at significantly elevated risk for emotional difficulties. The current manuscript examines the non-human and human literatures on amygdala development following caregiver deprivation and presents an argument that in the absence of the species-expected caregiver presence, human amygdala development exhibits rapid development and perhaps premature engagement that results in some of the emotional phenotypes observed following early institutional care.

Connecting developmental trajectories: Biases in face processing from infancy to adulthood

Abstract: The nature of the developmental trajectory of face recognition abilities from infancy through adulthood is multifaceted and currently not well understood. We argue that the understanding of this trajectory can be greatly informed by taking a more functionalist approach in which the influence of age-appropriate developmental tasks and goals are considered. To build this argument, we provide a focused review of developmental change across several important biases within face processing (species, race, age, and gender biases) from infancy through adulthood. We show that no existing theoretical framework can simultaneously and parsimoniously explain these very different trajectories and relative degrees of plasticity. We offer several examples of infant- and adolescent-specific developmental tasks that we predict have an essential influence on the content and description of information that individuals need to extract from faces at these very different developmental stages. Finally, we suggest that this approach may provide a unique opportunity to study the role of early experience in (i.e., age of acquisition effects) and the quality and range of experiences that are critical for shaping behaviors through the course of development, from infancy to adulthood.

Hormonal and physical markers of puberty and their relationship to adolescent-typical novelty-directed behavior

Abstract: The extent to which characteristic adolescent behaviors are associated with pubertal changes or driven by more general, puberty-independent developmental alterations is largely unknown. Using physiological and hormonal markers of puberty, this experiment characterized pubertal timing across adolescence and examined the relationships among these variables and novelty-directed behaviors. Males and females were tested for response to novelty at P28, P32, P36, P40, P44, P48, and P75, and examined for balano-preputial skinfold separation and sperm presence (males) or vaginal opening (females), followed by blood collection for hormonal assessments. Despite earlier pubertal maturation in females, with maturation generally completed by P36 in females and P44 in males, novelty-directed behavior peaked at P32 and P36 in both sexes, and was unrelated to pubertal measures. These data support the suggestion that the ontogenetic peak in this behavior during adolescence is not notably puberty dependent.

The development of fear learning and generalization in 8-13 year-olds.

Abstract: The current study examined developmental changes in fear learning and generalization in 40 healthy 8-13 year-olds using an aversive conditioning paradigm adapted from Lau et al. [Lau et al. [2008] Journal of the American Academy of Child and Adolescent Psychiatry 47:94-102]. In this task, the conditioned stimuli (CS+/CS-) are two neutral female faces, and the unconditioned stimulus is a fearful, screaming face. The second phase of the study also included a generalization stimulus (GS): a 50% blend of the CS± faces. The eye-blink startle reflex was utilized to measure defensive responding. Patterns of fear learning and generalization were qualified by child age. Older children demonstrated greater fear learning (i.e., larger startle during CS+ than CS-) than younger children. In addition, older children exhibited the typical pattern of generalization observed in adults, whereas younger children did not. Finally, fear learning also related to contingency awareness; only children who correctly identified the CS+ demonstrated fear-potentiated startle to the CS+. Clinical implications and future directions are discussed.

Genetic and epigenetic variation of the glucocorticoid receptor (NR3C1) in placenta and infant neurobehavior.

Abstract: The intrauterine environment can impact the developing infant by altering the function of the placenta through changes to the epigenetic regulatory features of this tissue. Genetic variation, too, may impact infant development or may modify the relationship between epigenetic alterations and infant outcomes. To examine the association of this variation with early life infant neurodevelopment, we examined the extent of DNA methylation of the glucocorticoid receptor gene (NR3C1) promoter and a common SNP in the promoter region in a series of 186 placentas from healthy newborn infants. We associated these molecular features with specific summary measures from the NICU Network Neurobehavioral Scales. After controlling for genotype and confounders, we identified significant associations of NR3C1 methylation with infant quality of movement (P=0.05) and with infant attention (P=0.05), and a potential interaction between methylation and genotype on infant attention score. These results suggest that epigenetic alteration of the NR3C1 gene in the placentas of genetically susceptible infants can have impacts on neurodevelopment which may have lifelong impact on neurobehavioral and mental health outcomes. Further research is needed to more precisely define these relationships and the interaction between epigenetic alterations and genetic variations on infant health.

Recovery of motor function after stroke

Abstract: The human brain possesses a remarkable ability to adapt in response to changing anatomical (e.g., aging) or environmental modifications. This form of neuroplasticity is important at all stages of life but is critical in neurological disorders such as amblyopia and stroke. This review focuses upon our new understanding of possible mechanisms underlying functional deficits evidenced after adult-onset stroke. We review the functional interactions between different brain regions that may contribute to motor disability after stroke and, based on this information, possible interventional approaches to motor stroke disability. New information now points to the involvement of non-primary motor areas and their interaction with the primary motor cortex as areas of interest. The emergence of this new information is likely to impact new efforts to develop more effective neurorehabilitative interventions using transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) that may be relevant to other neurological disorders such as amblyopia.

Mothers' responses to children's negative emotions and child emotion regulation: The moderating role of vagal suppression

Abstract: The current study examined the moderating effect of children's cardiac vagal suppression on the association between maternal socialization of negative emotions (supportive and nonsupportive responses) and children's emotion regulation behaviors. One hundred and ninety-seven 4-year-olds and their mothers participated. Mothers reported on their reactions to children's negative emotions and children's regulatory behaviors. Observed distraction, an adaptive self-regulatory strategy, and vagal suppression were assessed during a laboratory task designed to elicit frustration. Results indicated that children's vagal suppression moderated the association between mothers' nonsupportive emotion socialization and children's emotion regulation behaviors such that nonsupportive reactions to negative emotions predicted lower observed distraction and lower reported emotion regulation behaviors when children displayed lower levels of vagal suppression. No interaction was found between supportive maternal emotion socialization and vagal suppression for children's emotion regulation behaviors. Results suggest physiological regulation may serve as a buffer against nonsupportive emotion socialization.

Maturation of shoaling behavior is accompanied by changes in the dopaminergic and serotoninergic systems in zebrafish

Abstract: The zebrafish has been one of the preferred vertebrate model organisms of developmental biology, and is becoming an important research tool for behavioral neuroscience and behavior genetics. A prominent feature of zebrafish is their strong shoaling tendency. Most recently, the first paper investigating the development of shoaling in zebrafish demonstrated that a few days after hatching zebrafish do not shoal, but that shoaling tendency gradually increases during development. The current paper investigates this phenomenon using the nearest neighbor distance, a measure most frequently employed for the quantification of shoal cohesion in fish. We demonstrate that shoal cohesion increases with age, while thigmotaxis, “wall hugging”, does not show a consistent age-dependent change. The mechanisms underlying the maturation of shoaling are unknown. HPLC analysis of whole brain extracts finds the concentration of dopamine, DOPAC, serotonin, and 5-HIAA normalized to total brain protein weight to increase with age. Although the behavioral and neurochemical results are only correlative at this point, they may open a new avenue into the investigation of the mechanisms and development of social behavior in zebrafish.

Functional connectivity and neurological recovery

Abstract: Modern theories of brain function emphasize the importance of distributed functional networks and synchronized activity within and between networks in mediating cognitive functions. This view highlights the importance of considering brain-behavior relationships after focsal lesions not only as the result of local structural damage but also as a more widespread alteration of the physiological state of networks connected to the lesion. Recent findings demonstrate coherent activity in large-scale brain networks not only during task performance, but also, surprisingly, at rest in the absence of stimuli, tasks, or overt responses. Moreover, breakdown of coherent activity at rest, even in regions that are structurally intact, correlates with behavioral deficits and with their recovery after injury. This network perspective is fundamental to understand not only healthy brain function, but also the pathophysiology of brain injuries, mechanisms of functional recovery, and the basis for novel interventions for therapy.

Handedness for grasping objects and declarative pointing: a longitudinal study.

Abstract: It is still unclear whether infants become right-handed because of their left-hemisphere specialization for language (through gestural communication for instance), whether they speak predominantly with their left hemisphere because of this hemisphere's superiority in controlling sequential actions which first results in right-handedness, or whether the two lateralization processes develop independently. To tackle this question, we followed 26 human infants from 8 to 20 months to evaluate the temporal relationship between the emergence of hand preference for grasping objects and for declarative pointing (communicative gesture). Our results show that when grasping and pointing are compared in similar conditions, with objects presented in several spatial positions, the tendency to use the right hand is significantly larger for pointing than for grasping, and both hand preferences are loosely correlated. This suggests that, at least at the age studied here, hand preferences for grasping and for declarative pointing develop relatively independently.

Electrocortical and behavioral measures of response monitoring in young children during a Go/No-Go task

Abstract: The current study examined behavioral measures and response-locked event-related brain potentials (ERPs) derived from a Go/No-Go task in a large (N = 328) sample of 5- to 7-year-olds in order to better understand the early development of response monitoring and the impact of child age and sex. In particular, the error-related negativity (ERN, defined on both error trials alone and the difference between error and correct trials, or ΔERN), correct response negativity (CRN), and error positivity (Pe) were examined. Overall, the ERN, CRN, and the Pe were spatially and temporally similar to those measured in adults and older children. Even within our narrow age range, older children were faster and more accurate; a more negative ΔERN and a more positive Pe were associated with: increasing age, increased accuracy, and faster reaction times on errors, suggesting these enhanced components reflected more efficient response monitoring of errors over development. Girls were slower and more accurate than boys, although both genders exhibited comparable ERPs. Younger children and girls were characterized by increased posterror slowing, although they did not demonstrate improved posterror accuracy. Posterror slowing was also related to a larger Pe and reduced posterror accuracy. Collectively, these data suggest that posterror slowing may be unrelated to cognitive control and may, like the Pe, reflect an orienting response to errors.

The development of whisker control in rats in relation to locomotion.

Abstract: Adult rats sweep their large facial whiskers (macrovibrissae) back and forth in a rhythmic pattern known as “whisking”. Here we examine how these whisker movements develop in relation to other aspects of exploratory behavior, particularly locomotion. We analyzed 963 high-speed video recordings of neonatal rats, from P1 (Post-natal day 1) to P21, and measured the emergence of whisker control and of head, body, and limb movements. Prior to P11, whisker movements were largely limited to unilateral retractions accompanying head turns. Between P11 and P13 bilateral whisking emerged alongside increased forward locomotion and improved control of the head. Contact-induced modulations of whisking symmetry, synchrony, and whisker spread emerge shortly thereafter but continue to develop until at least P18, coinciding with the emergence of adult-like locomotion patterns such as rearing. Overall, whisking develops alongside increasing locomotor competence indicating that active vibrissal sensing plays an important role in the exploratory behavior of the developing animal. © 2011 Wiley Periodicals, Inc. Dev Psychobiol 54:151-168, 2012.

Age-related changes in learning across early childhood: a new imitation task.

Abstract: Imitation plays a critical role in social and cognitive development, but the social learning mechanisms contributing to the development of imitation are not well understood. We developed a new imitation task designed to examine social learning mechanisms across the early childhood period. The new task involves assembly of abstract-shaped puzzle pieces in an arbitrary sequence on a magnet board. Additionally, we introduce a new scoring system that extends traditional goal-directed imitation scoring to include measures of both children's success at copying gestures (sliding the puzzle pieces) and goals (connecting the puzzle pieces). In Experiment 1, we demonstrated an age-invariant baseline from 1.5 to 3.5 years of age, accompanied by age-related changes in success at copying goals and gestures from a live demonstrator. In Experiment 2, we applied our new task to learning following a video demonstration. Imitation performance in the video demonstration group lagged behind that of the live demonstration group, showing a protracted video deficit effect. Across both experiments, children were more likely to copy gestures at earlier ages, suggesting mimicry, and only later copy both goals and gestures, suggesting imitation. Taken together, the findings suggest that different social learning strategies may predominate in imitation learning dependent upon the degree of object affordance, task novelty, and task complexity.

Age, experience, injury, and the changing brain

Abstract: The fundamental concept in the emerging field of rehabilitation and brain plasticity is that although there is much constancy in brain function and organization across our lifetime, there is remarkable variability as well. This variability reflects the brain's capacity to alter its structure and function in reaction to environmental diversity as well as to perturbations including injury throughout the lifespan. Although the term brain plasticity is now widely used, it is not easily defined and is used to refer to changes at many levels in the nervous system ranging from molecular events, such as changes in gene expression, to behavior (e.g., Shaw & McEachern (Eds.) [2001]. Toward a Theory of Neuroplasticity. Philadelphia, USA: Psychology Press). The focus of our work has been to correlate changes in behavior, neuronal morphology, and the organization of motor maps after cortical injury throughout the lifespan. In this article, we review evidence we have collected from a rat model of normal development and the effects of brain injury, and comment on the general principals that may apply to human stroke and amblyopia.

Epigenetics of neurobiology and behavior during development and adulthood.

Abstract: Gene-environment interactions have long been recognized for their important role in mediating the development and functions of the central nervous system (CNS). The study of DNA methylation and histone modifications, biochemical processes collectively referred to as epigenetic mechanisms, is helping to elucidate how gene-environmental interactions alter neurobiology and behavior over the course of the lifespan. In this review, landmark and recent studies that highlight the role of epigenetic mechanisms in the sustained effects of early-life experiences on gene activity and behavioral outcome will be discussed. Likewise, studies that implicate epigenetics in CNS and behavioral plasticity in the adult animal will be discussed. As our current understanding of epigenetics in these capacities is still evolving, epigenetic research will continue to be of considerable interest for understanding the molecular mechanisms mediating neurobiology and behavior both within and outside of sensitive periods of development.

Early experience shapes vocal neural coding and perception in songbirds

Abstract: Vocal production and perception form our primary means of communication. The role of experience in the neural processing and perception of vocal sounds is an important issue in our pursuit to understand how we acquire and perceive speech and what goes wrong when we can’t understand speech. A significant body of work exists on the role of experience in the development of speech processing and perception in typical and language-impaired children (Chandrasekaran, Hornickel, Skoe, Nicol, & Kraus, 2009; Johnson, Nicol, Zecker, & Kraus, 2008; Kuhl, 2000, 2004, 2010; Kuhl, Tsao, & Liu, 2003; Russo, Nicol, Zecker, Hayes, & Kraus, 2005; Russo et al., 2008; Tsao, Liu, & Kuhl, 2004; Warrier, Johnson, Hayes, Nicol, & Kraus, 2004; Werker & Tees, 1992; Wible, Nicol, & Kraus, 2005). Speech perception research is informed and complemented by research on the neural processing and perception of vocalizations in animals whose experiences can be controlled and brains can be studied at the resolution of single neurons. Animals that learn vocalizations are particularly advantageous because they offer the opportunity to manipulate and measure learning that is specific to vocal communication and to correlate learned behavior with neural mechanisms that are influenced by experience. Though vocal communication is common among animals, vocal learning is rare. Only humans, some cetaceans, and three clades of birds (parrots, hummingbirds and songbirds) are known to learn their vocalizations (Beecher & Brenowitz, 2005). There is some evidence that elephants and bats may be vocal learners as well (Knornschild, Nagy, Metz, Mayer, & von Helversen, 2010; Poole, Tyack, Stoeger-Horwath, & Watwood, 2005). Of these potential animal models, songbirds are by far the most thoroughly studied, and numerous similarities exist between speech and birdsong (Doupe & Kuhl, 1999). Examples include: 1) developmental sensitive periods for vocal learning (Marler, 1997); 2) learning through imitation of adult models (Marler, 1997; Saar, Mitra, Deregnaucourt, & Tchernichovski, 2008); 3) a dependence of vocal behavior on auditory feedback (Konishi, 2004; Woolley, 2004); 4) individual recognition via unique vocalizations (Catchpole & Slater, 2008; Gentner, 2004); and 5) lateralized vocal processing in sensory and sensorimotor brain regions (George, Cousillas, Richard, & Hausberger, 2005; Hauber, Cassey, Woolley, & Theunissen, 2007; Poirier, Boumans, Verhoye, Balthazart, & Van der Linden, 2009; Williams, Crane, Hale, Esposito, & Nottebohm, 1992). Because of the parallels between speech and birdsong and the evolutionary conservation of vocal processing circuitry (Reiner, Perkel, Mello, & Jarvis, 2008; Reiner, Yamamoto, & Karten, 2005; Wang, Brzozowska-Prechtl, & Karten, 2010), the songbird has emerged as a promising model system for studying the neural basis of learned vocal communication. Brain mechanisms of vocal perception are a current research focus due, in part, to increased awareness of neurological disorders that include impaired speech perception, such as autism, Asperger Syndrome and auditory processing disorder. Studies published in the last decade indicate that the vocal communication sounds heard early in life provide experience that is needed for the normal development of the auditory system and, consequently, for perceptual processes that underlie vocal communication. Here, I review studies that address how developmental experience shapes auditory perception and the neural coding of sound in songbirds. The role of experience in songbird vocal production and motor coding have been extensively reviewed elsewhere (Brainard, 2004; Doupe, Perkel, Reiner, & Stern, 2005; Fee & Scharff, 2010; Konishi, 2010; Margoliash, 2010; Mooney, 2009), but I will briefly discuss this topic because it is tightly linked to perceptual development.

Organizational effects of oxytocin on serotonin innervation.

Abstract: Oxytocin (OT) has an organizational effect within the central nervous system and can have long-lasting effects on the expression of social behavior. OT has recently been implicated in modulating the release of serotonin through activation of receptors in the raphe nuclei. Here we test the hypothesis that OT can have an organizational effect on the serotonergic system. Male prairie voles received an intraperitoneal injection on postnatal day 1 with 3.0 or .3 µg OT, an OT antagonist, or a saline control. Brains were collected on day 21 and immunostained for serotonin. Serotonin axons were quantified in the anterior hypothalamus, cortical amygdala, medial amygdala, paraventricular nucleus of the hypothalamus, and ventromedial hypothalamus. Males treated with 3.0 µg OT displayed significantly higher serotonin axon length densities in the anterior hypothalamus, cortical amygdala, and the ventromedial hypothalamus than control males. These results support the hypothesis that OT has an organizational effect on the serotonin system during the neonatal period, and that these effects are site-specific.

The development of the uncanny valley in infants.

Abstract: When adults view very realistic humanoid robots or computer avatars they often exhibit an aversion to them. This phenomenon, known as the "uncanny valley," is assumed to be evolutionary in origin, perhaps tapping into modules for disgust or attractiveness that detect violations of our normal expectations regarding social signals. Here, we test an alternative hypothesis that the uncanny valley is developmental in origin and, thus, that specific early experience with real human faces leads to its eventual emergence. To test this idea, we measured visual preferences in response to all possible pairs of a human face, realistic avatar face, and an unrealistic avatar face in groups of 6-, 8-, 10-, and 12-month-old infants. Consistent with the developmental hypothesis, we found that the uncanny valley effect emerges at 12 months of age suggesting that perceptual experience with real human faces is critical to its emergence.

Transgenerational effects of infantile adversity and enrichment in male and female rats.

Abstract: To discover whether the accumulation of life's experiences, adverse and enriching, inform, and serve the following generation by inheritance we examine whether stress to a weanling female will influence her future offspring, whether prereproductive enrichment to the dam, or postweaning enrichment to the offspring, can reverse the transgenerational effects of stress, and whether, like adversity, enrichment might have transgenerational effects. Female rats were exposed to stressors when they were 27-29 days old. Half of these females and their controls were then raised in an enriched environment from weaning until mating at 60 days to examine whether preproduction enrichment reverses the effects of preproduction stress on offspring. Half of the offspring of each group were raised in an enriched environment after weaning, to see whether it reverses the effects of preproduction stress and buttresses prereproductive enrichment. Behavior was examined in 625 adult offspring in 16 groups covering all permutations of the experimental variables (preproduction weanling stress (PS), preproduction enrichment (PE), offspring enrichment (OE), sex). Exploration, avoidance learning, startle, and social interaction were tested. Results reveal that very early prereproductive experience in females, adverse or enriching, will transgenerationally influence their future offspring, depending on the behavior tested and sex. Our finding that enrichment, whether to the parent or offspring generation, can ameliorate the transgenerational impact of adversity, has novel implications for the malleability of transgenerational inheritance, and its individual, social, and therapeutic impact.

The development of implicit learning from infancy to adulthood: item frequencies, relations, and cognitive flexibility.

Abstract: The majority of cognitive processes show measurable change over the lifespan. However, some argue that implicit learning from environmental structure is development invariant [e.g., Muelemans et al. [1998] Experimental Child Psychology, 69, 199–221; Reber [1993] Implicit learning and tacit knowledge: An essay on the cognitive unconscious. Oxford University Press], while others have shown that adults learn faster than children [Thomas et al. [2004] Journal of Cognitive Neuroscience, 16, 1339–1351]. In two experiments, we tested infants through adults using the same saccade latency measure and behavioral learning paradigm. We examined implicit learning when subjects are presented with interleaved regularities acting on one item, as well as the ability to adjust behavior when learned information is violated. In one comparison, the first- (item frequencies) and second- (spatiotemporal item relations) order statistics are in conflict, allowing us to examine flexibility in learning from multiple parameters. Data from Experiment 1 (N = 90, 6- to 30-year olds) showed no developmental differences in either implicit learning from environmental regularity or flexibility of learning from conflicting parameters across our age range. Accuracy data showed that children are especially sensitive to low frequency relative to high frequency items. In Experiment 2, we showed that 7- to 11-month-old infants had a saccade latency profile that was consistent with task structure, that is, they simultaneously learned both item frequencies and spatiotemporal relations, as indicated by data patterns similar to those obtained in Experiment 1. Taken together, these data provide support for developmental invariance in implicit learning from environmental regularities. © 2012 Wiley Periodicals,Inc. Dev Psychobiol 54: 664–673, 2012.

Atypical development of resting respiratory sinus arrhythmia in children at high risk for depression.

Abstract: Compromised respiratory sinus arrhythmia (RSA, i.e., low cardiac vagal control) frequently characterizes clinically depressed adults and also has been detected in infants of depressed mothers; however, its existence has not been established in older at-risk offspring. We investigated developmental patterns of RSA in a sample of 163 5-14 year-old children, who were either at high risk for depression (due to having a parent with a childhood-onset mood disorder) or low-risk for depression. We hypothesized that high-risk children have lower resting RSA than do low-risk children, which could reflect atypical developmental trajectories. Children's RSA was assessed during resting baseline periods on multiple occasions, typically one-year apart. Linear growth modeling indicated a group by age interaction. Low-risk children (but not the high-risk children) exhibited a significantly increasing trajectory in resting RSA with age. Mood disorders in offspring did not account for the Group X Age interaction effect. Our study provides new evidence that children at high risk for depression have an atypical developmental trajectory of RSA across late childhood.

Sympathetic and parasympathetic responses to social stress across adolescence.

Abstract: Many transformations that occur in adolescence are related to emotion and emotion regulation, yet very little is known about the autonomic underpinnings of these changes. The aim of the study was to document age-related differences in autonomic responses to social stress and relations to emotion regulation. Ninety-nine female adolescents engaged in a paced breathing and a spontaneous speech task while electrocardiography measurements were taken. Spectral decomposition of the heart period data was used to create measures of sympathetic and parasympathetic activity. Results revealed a positive correlation between age and sympathetic activity and a negative correlation between age and parasympathetic activity. These findings contribute to a better understanding of the age-related norms of cardiac variability across adolescence.

Human puberty: salivary melatonin profiles in constant conditions.

Abstract: This analysis examined the relative contributions of sex, age, body mass index (BMI), and puberty (Tanner) stage on salivary melatonin amplitude. Sixty-nine children and adolescents (30 females; 9.6-17.8 years) were examined for Tanner stage. Serial salivary melatonin samples were collected in controlled conditions, from which these melatonin amplitude measures were derived: area under the curve (AUC) and maximum value (MAX). AUC declined with advancing Tanner stage. This melatonin decline was similar between boys and girls, but girls secreted more melatonin compared to boys. Tanner stage and sex explained AUC variability, but age and BMI did not; similar results emerged for MAX. These results indicate that puberty stage may either mediate the decline of melatonin, or the decrease in melatonin amplitude may be an indicator of pubertal progression. These findings also indicate that the melatonin decline during puberty is not entirely accounted for by body mass or by age.

Pulling to stand: common trajectories and individual differences in development.

Abstract: This longitudinal study of 27 infants examined the development of pulling-to-stand (PTS). In general, infants began PTS using a two-leg strategy and transitioned to a half-kneel strategy. As a group, infants showed no preference for either strategy at the onset of PTS, switching between strategies until half-kneeling became the dominant pattern about 1 month after the onset of PTS. Examination of individual developmental trajectories revealed variability in age at PTS onset, time between PTS onset and half-kneel strategy onset, duration of the two-leg strategy as the dominant pattern, time until the half-kneel strategy became the dominant pattern, shape of the transition between strategies (gradual vs. abrupt), and timing of PTS relative to onset of other motor milestones. We discuss variation in developmental trajectory in terms of adaptive behavior during the acquisition of new skills and as a process shaped by infants' unique experiences prior to and during the acquisition period.

Longitudinal patterns of autonomic nervous system responding to emotion evocation among children with conduct problems and/or depression

Abstract: Despite divergent presentations at the symptom level, conduct disorder (CD) and depression are highly comorbid conditions in childhood and adolescence (Angold, Costello, & Erkanli, 1999). Conduct disorder is defined by persistent and repeated violations of social rules and the rights of others, whereas depression is characterized by sadness and anhedonia, often accompanied by anxiety (American Psychiatric Association, 2000). Nevertheless, youth with CD experience much higher rates of depression—and youth with depression experience much higher rates of CD—than found in the general population. Epidemiologic samples, for example, yield CD co-occurrence rates ranging from 15% to 24% among depressed youth (Zoccolillo, 1992). There are two somewhat divergent perspectives on risk associated with comorbidity of internalizing and externalizing disorders. According to some reports, such heterotypic comorbidity is associated with greater functional impairment than either CD or depression alone (see e.g., Goodman, Schwab-Stone, Lahey, Shaffer, & Jensen, 2000; Kopp & Beauchaine, 2007). Comorbid CD and depression may portend lower academic achievement (Marmorstein & Iacono, 2004), poorer social competence and more involvement with deviant peers (Ingoldsby, Kohl, McMahon, & Lengua, 2006), and greater risk for substance abuse (Brenner & Beauchaine, 2011) than either disorder alone. Furthermore, some longitudinal studies indicate especially poor clinical trajectories (Beyers & Loeber, 2003), high risk for recurrent depression (Rohde, Clarke, Lewinsohn, Seeley, & Kaufman, 2001), more suicide attempts (Fombonne et al., 2001), and greater levels of adult criminal behavior (Copeland, Miller-Johnson, Keeler, Angold, & Costello, 2007). Given the poor outcomes associated with heterotypic comorbidity, it may be especially important to identify vulnerability early, which might improve prevention outcomes (e.g., Beauchaine, Neuhaus, Brenner, & Gatzke-Kopp, 2008). In contrast, a smaller but growing literature suggests that comorbid internalizing disorders may offer partial protection from especially poor outcomes among children and adolescents with CD and related externalizing disorders. For example, symptoms of anxiety predict better response to treatment among children with ADHD and CD (Jensen et al., 2001). Furthermore, some studies indicate that youth with CD and comorbid anxiety are less aggressive physically, regarded less negatively by their peers, and experience fewer police contacts than youth with CD alone (Walker et al., 1991). Neuroanatomically, symptoms of anxiety and depression are associated with less severe structural compromises in brain regions subserving motivation and behavior regulation—including the caudate, hippocampus, and anterior cingulated cortex—among externalizing males (Sauder, Beauchaine, Gatzke-Kopp, Shannon, & Alyward, in press). These findings are consistent with the hypothesis that internalizing symptoms serve to dampen excessive approach behaviors, including conduct problems and aggression, among those predisposed to externalizing conduct (e.g., Beauchaine, 2001). One potentially fruitful strategy for increasing our understanding of heterotypic comorbidity, and disentangling alternative viewpoints such as those articulated above, is by evaluating biomarkers of emotion regulation/dysregulation (e.g., Beauchaine & Gatzke-Kopp, in press). As we have described in detail elsewhere, emotion dysregulation characterizes both internalizing and externalizing disorders, at both behavioral and physiological levels of analysis (see e.g., Beauchaine, 2001; Beauchaine, Gatzke-Kopp, & Mead, 2007; Beauchaine, Klein, Crowell, Derbidge, & Gatzke-Kopp, 2009; Vasilev, Crowell, Beauchaine, Mead, & Gatzke-Kopp, 2009). For example, children with clinical levels of conduct problems and children with clinical levels of depression show consistently lower respiratory sinus arrhythmia (RSA) at baseline, and consistently greater RSA reactivity to emotion evocation than controls (e.g., Beauchaine, Katkin, Strassberg, & Snarr, 2001; Boyce et al., 2001; Mezzacappa et al., 1997; Shannon, Beauchaine, Brenner, Neuhaus, & Gatzke-Kopp, 2007)1. To date, however, most of this research has evaluated main effects of CD or depression on autonomic functioning, ignoring possible CD × Depression interactions. In addition, few studies conducted to date have evaluated autonomic markers of emotion dysregulation longitudinally. In this study, we evaluate longitudinal patterns of RSA and RSA reactivity in a cohort of middle school children who were diagnosed at ages 8–12 years with CD, depression, comorbid CD and depression, or no psychiatric condition. Studying the development of RSA and RSA reactivity is important given an expanding literature linking patterns of RSA responding to (1) central nervous system substrates of emotion regulation/dysregulation (e.g., Porges, 1995, 2007; Beauchaine et al., 2007; Thayer & Lane, 2000), (2) socialization processes within families (Kupper et al., 2004, 2005), and (3) self-reports of developing ER skills across middle childhood and adolescence (Vasilev et al., 2009). In turn, strong emotion regulation skills offer protection from emerging psychopathology (see Beauchaine & Gatzke-Kopp, in press; Shannon et al., 2007). Nevertheless, very few longitudinal studies have examined autonomic nervous system-linked cardiac activity/reactivity within this age range—particularly among children with clinical levels of conduct problems and depression. Ordinarily, RSA indexes parasympathetic nervous system (PNS)-linked cardiac activity (see Berntson et al., 1997). RSA quantifies naturally occurring oscillations in heart rate across the respiratory cycle. Phasic decreases in RSA occur during the experience of strong emotions, including empathy, sadness, panic, anger, and fight/flight/freeze responding (see e.g., Beauchaine, 2001; George et al., 1989; Marsh, Beauchaine, & Williams, 2008). Among other functions, such decreases in RSA facilitate increased cardiac output to cope with real or perceived stressors (see Beauchaine et al., 2007; Porges, 1995). Studies of normative samples indicate consistent positive associations between baseline RSA and competent social behavior and self-regulation (e.g., Eisenberg et al., 1995; Fox & Field, 1989). In contrast, although studies of typically developing children have linked modest decreases in RSA during a host of challenges to positive outcomes including protection from psychopathology (e.g., Blandon et al., 2008; Calkins & Keane, 2004; El-Sheikh et al., 2009; Gottman & Katz, 2002), excessive RSA reactivity to such challenges, as noted above, is observed consistently in psychiatric samples of internalizing and externalizing children, adolescents, and adults (Beauchaine et al., 2001; Beauchaine & Gatzke-Kopp, in press; Boyce et al., 2001; Crowell et al., 2005; Mezzacappa et al., 1997; Shannon et al., 2007). This seeming inconsistency is likely because modest decreases in RSA reflect competent attention allocation, whereas excessive RSA reactivity reflects emotional lability and fight/flight/freeze responding (see Beauchaine, 2009; Porges, 1995; Suess, Porges, & Plude, 1994). As already noted, however, little attention has been paid to the association between RSA and comorbid CD and depression. In this article, we analyze data from a longitudinal study of developing conduct problems, depression, and heterotypic comorbidity in children who were 8–12 years old at the first of three annual assessments. Consistent with the literature reviewed above, we anticipated that both CD and depression would be associated with compromised parasympathetic-linked cardiac function compared with controls. In addition, we expected children with comorbid CD and depression to exhibit particularly low baseline RSA and especially high RSA reactivity to emotion-induction. In other words, we predicted a CD × Depression interaction in predicting low RSA and high RSA reactivity across development, consistent with the notion that heterotypic comorbidity is synergistic—not protective.

Frontal EEG asymmetry and fear reactivity in different contexts at 10 months

Abstract: Individual differences in observed and maternal-rated fear behaviors and frontal electroencephalogram (EEG) asymmetry were examined in normally developing 10-month-old infants. EEG was recorded during resting baseline, as well as during stranger approach, mask presentation, and toy spider presentation. Mothers completed the Infant Behavior Questionnaire. For mask presentation, baseline and task right frontal EEG asymmetry as well as maternal ratings predicted fear behavior during the mask task. For stranger approach, task-related right frontal EEG asymmetry predicted fear behavior during stranger approach after controlling for baseline asymmetry. There was a trend for task-related right frontal EEG asymmetry to predict fear during presentation of a toy spider after controlling for baseline asymmetry. Maternal report of temperament only added unique variance to the prediction of one fear task after controlling for baseline and task EEG. Assessing fear in multiple situations revealed context-specific individual differences in infant fear.