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PubMed1999

A hot/cool-system analysis of delay of gratification: dynamics of willpower.

A 2-system framework is proposed for understanding the processes that enable--and undermine--self-control or "willpower" as exemplified in the delay of gratification paradigm. A cool, cognitive "know" system and a hot, emotional "go" system are postulated. The cool system is cognitive, emotionally neutral, contemplative, flexible, integrated, coherent, spatiotemporal, slow, episodic, and strategic. It is the seat of self-regulation and self-control. The hot system is the basis of emotionality, fears as well as passions--impulsive and reflexive--initially controlled by innate releasing stimuli (and, thus, literally under "stimulus control"): it is fundamental for emotional (classical) conditioning and undermines efforts at self-control. The balance between the hot and cool systems is determined by stress, developmental level, and the individual's self-regulatory dynamics. The interactions between these systems allow explanation of findings on willpower from 3 decades of research.

Disruptive, Impulse Control, and Conduct Disorders↗
PubMed2001

A developmental and psychobiologic framework for understanding the role of culture in child and adolescent psychiatry.

In summary, despite these widely accepted interdisciplinary perspectives on the role of culture, the DSM framework lacks a culturally meaningful usage. For Kleinman, the changes on culture in the DSM-IV were "too little, too late." The cultural formulation and a glossary of culture-bound syndromes were included in its appendix. The acceptance by the DSM-IV task force of the notion of cultural variations in clinical presentation of disorders may be reflective of changes to come in the future. The current DSM-IV has more of a descriptive psycho-pathologic approach rather than an integrated cross-cultural, psychobiologic, developmental approach, however. The developmental perspective in psychiatry is emerging as a "bridge" for consilience through evidence-based scientific understanding and conciliation through clinical practice. This perspective is unique because it is intrinsic to different aspects of psychiatry. It readily accommodates the descriptive-empirical model by means of concepts borrowed from developmental psychopathology and psychobiology. These concepts include normalcy, life cycle, risk and resilience, and protective mechanisms within a dynamic construction of development that involves an interchange among biology-person-society-culture. The developmental perspective also can make important contributions to a process-oriented approach to measurement beyond a textually defined DSM structure. The developmentally operationalized dimensional constructs offer to expand psychiatry's domains beyond diagnosable conditions and illness boundaries. The developmental perspective argues for early preventive and therapeutic interventions for a broad array of applications based on demonstrated evidence of efficacy. Finally, the developmental perspective with its social and cultural contexts is an intrinsic complement to Kandel's framework for an expanded training of psychiatrists in the neurosciences and the associated innovative technologies for understanding the mechanism of structural and functional changes in the brain in various contexts and categories.

Adolescent↗
PubMed1990

[Dynamic balance in the prevention of growth disorders].

The authors examine the characteristic of the standing position and the successive developmental phases of proprioceptive afferent stimuli which lead to the coordination of muscles responsible for the control of static and dynamic balance. Subsequently, they analyze pathological changes due to intrinsic factors which are likely to be involved in dysmorphisms of the spine, and to extrinsic factors such as those brought about by orthotic or surgical intervention on the spine. The authors conclude stressing the clinical and prognostic importance of global evaluation of kinetic alterations resulting from zonal changes in the entire complex of the locomotor system.

Growth Disorders↗
PubMed1997

Altered patterns of cerebral activity during speech and language production in developmental stuttering. An H2(15)O positron emission tomography study.

To assess dynamic brain function in adults who had stuttered since childhood, regional cerebral blood flow (rCBF) was measured with H2O and PET during a series of speech and language tasks designed to evoke or attenuate stuttering. Speech samples were acquired simultaneously and quantitatively compared with the PET images. Both hierarchical task contrasts and correlational analyses (rCBF versus weighted measures of dysfluency) were performed. rCBF patterns in stuttering subjects differed markedly during the formulation and expression of language, failing to demonstrate left hemispheric lateralization typically observed in controls; instead, regional responses were either absent, bilateral or lateralized to the right hemisphere. Significant differences were detected between groups when all subjects were fluent-during both language formulation and non-linguistic oral motor tasks-demonstrating that cerebral function may be fundamentally different in persons who stutter, even in the absence of stuttering. Comparison of scans acquired during fluency versus dysfluency-evoking tasks suggested that during the production of stuttered speech, anterior forebrain regions-which play an a role in the regulation of motor function-are disproportionately active in stuttering subjects, while post-rolandic regions-which play a role in perception and decoding of sensory information-are relatively silent. Comparison of scans acquired during these conditions in control subjects, which provide information about the sensorimotor or cognitive features of the language tasks themselves, suggest a mechanism by which fluency-evoking maneuvers might differentially affect activity in these anterior and posterior brain regions and may thus facilitate fluent speech production in individuals who stutter. Both correlational and contrast analyses suggest that right and left hemispheres play distinct and opposing roles in the generation of stuttering symptoms: activation of left hemispheric regions appears to be related to the production of stuttered speech, while activation of right hemispheric regions may represent compensatory processes associated with attenuation of stuttering symptoms.

Adult↗
PubMed2004

Role of biokinetics in risk assessment of drugs and chemicals in children.

Whether children incur different risks from xenobiotics than adults will depend on the exposure, biokinetics, and dynamics of compound. In this paper, current knowledge on developmental physiology and possible effects on biokinetics are evaluated and the role of biokinetics in risk assessment both for drugs and chemicals is discussed. It is concluded that most dramatic age-related physiological changes that may affect biokinetics occur in the first 6-12 months of age. The difference in internal exposure between children and adults can generally be predicted from already known developmental physiological differences. However, for risk assessment it will also be necessary to determine whether internal exposure is within the drug's therapeutic window or if it will exceed the NOAEL of a chemical. Furthermore, the effects of internal exposure of potentially harmful compounds on developing organ systems is of utmost importance. However, knowledge on this aspect is very limited. Risk assessment in children could be improved by: (1) application of pediatric PBPK-models in order to gain insight into internal exposure in children, (2) studies in juvenile animals for studying effects on developing systems, and (3) extrapolation of knowledge on the relationship between internal exposure and dynamics for drugs to other chemicals.

Adolescent↗
PubMed2004

Unique considerations in caring for a pediatric burn patient: a developmental approach.

Treatment of the child with a burn injury is a dynamic and complex process incorporating pediatric physiology, cognition, and emotional development. An understanding of child development and the importance of the family plays a key role in the child's recovery at all ages. An account of a teenager's burn injury is depicted through the voices of the teenager and his nurse. This article explores that experience and provides a comprehensive look at the role of the burn team, family, and community in his recovery.

Adaptation, Psychological↗
PubMed2005

Introduction: matrix biology in the 21st century. From a static-rheological role to a dynamic-signaling function.

These introductory remarks contain a succinct reminder of the developmental history of matrix biology, from the descriptive biochemistry of connective tissues to the up to date cell biology of extracellular matrices. The rapid growth of this discipline makes it prohibitive to give a complete coverage of recent results on all aspects of matrix biology and pathology. The articles in this special issue concern several of the ECM-macromolecules and some of their functional characteristics. No space remained for reviews on matrix related pathologies. As a partial compensation some recent aspects of cell-cell and cell-matrix interactions in malignant growth are mentioned in this introduction.

Animals↗
PubMed1997

The relevance of developmental hemostasis to hemorrhagic disorders of newborns.

The hemostatic system is a dynamic evolving process that is age-dependent. Components of the hemostatic system are synthesized in early fetal life and do not cross the placenta from mother to fetus. However, plasma concentrations of proteins involved in hemostasis significantly differ from adults. Physiological reference ranges are available for premature infants, full-term infants and children from ages 1 to 16 years. In the coagulation system, plasma concentrations of the vitamin K-dependent and contact factors are decreased at birth, whereas other factors such as fibrinogen, FV, FVIII, and FXIII are similar or increased compared with adults at birth. In the fibrinolytic system, plasma concentrations of plasminogen are decreased at birth, whereas tissue plasminogen activator and plasminogen activator inhibitor are increased. Clinically, the hemostatic system of the young is effective and healthy infants do not suffer from spontaneous hemorrhagic complications. However, infants are more vulnerable, compared with older patients, for bleeding in the presence of either congenital or acquired haemostatic defects. Severe congenital bleeding disorders, although rare, frequently present in the newborn period. The most common acquired causes of bleeding newborns include disseminated intravascular coagulation, vitamin K deficiency, and liver disease. A description of these disorders and treatment guidelines are provided.

Blood Coagulation↗
PubMed2000

A developmental atlas of rat mammary gland histology.

The mammary gland is a dynamic tissue that undergoes epithelial expansion and invasion during puberty and cycles of branching and lobular morphogenesis, secretory differentiation, and regression during pregnancy, lactation, and involution. The alteration in the mammary gland epithelium during its postnatal differentiation is accompanied by changes in the multiple stromal cell types present in this complex tissue. The postnatal plasticity of the epithelium, endothelium, and stromal cells of the mammary gland may contribute to its susceptibility to carcinogenesis. The purpose of this review is to assist researchers in recognizing histological changes in the epithelium and stroma of the rat mammary gland throughout development.

Aging↗
PubMed1989

A developmental study of the interlimb coordination in running and galloping.

Using a dynamical systems perspective on motor behavior, it was predicted that interlimb coordination of running and galloping would behave like coupled, nonlinear, limit-cycle oscillators, which show the properties of phase locking, entrainment, and structural stability. Female subjects ranging in age from 2.5 years to adult were filmed while running and galloping with and without a weight perturbation. Analysis of both temporal- and amplitude-phasing measures revealed that both gaits demonstrated oscillatory properties. Differences between gaits and across age were primarily a matter of degree. In general, children 4 years of age and below had slightly less table phasing patterns, and all age groups showed slightly less ability in the gallop, particularly with amplitude phasing.

Journal Article↗
PubMed2006

A neurophysiological perspective on sleep and its maturation.

Neurophysiological studies of sleep have increasingly focused on underlying dynamic processes. This would appear particularly relevant to the developmental aspects of sleep. Involvement of sleep-dependent mechanisms in emotional processing, as well as perceptual-sensory, perceptual-motor, and cognitive learning, mostly studied in adults, may play major roles in development. Rapid eye movement (REM) sleep, which is generated by complex neuronal interactions within the pontine reticular formation, and non-REM sleep, which arises from activities in the thalamocortical network, are specifically implicated in different aspects of long-term memory systems. They evolve from previous physiological and behavioural states which can be traced back to the fetal period. Further studies are needed to clearly identify functions reflected by hallmarks of sleep stages, such as spindles and K complexes. A better understanding of the maturational aspects of sleep should provide important insights into physiological development. Assessment approaches taking dynamic characteristics of sleep into account may contribute to the design of better targeted management of sleep-related problems in neurodevelopmental conditions.

Cerebral Cortex↗
PubMed2004

DNA replication-timing analysis of human chromosome 22 at high resolution and different developmental states.

Duplication of the genome during the S phase of the cell cycle does not occur simultaneously; rather, different sequences are replicated at different times. The replication timing of specific sequences can change during development; however, the determinants of this dynamic process are poorly understood. To gain insights into the contribution of developmental state, genomic sequence, and transcriptional activity to replication timing, we investigated the timing of DNA replication at high resolution along an entire human chromosome (chromosome 22) in two different cell types. The pattern of replication timing was correlated with respect to annotated genes, gene expression, novel transcribed regions of unknown function, sequence composition, and cytological features. We observed that chromosome 22 contains regions of early- and late-replicating domains of 100 kb to 2 Mb, many (but not all) of which are associated with previously described chromosomal bands. In both cell types, expressed sequences are replicated earlier than nontranscribed regions. However, several highly transcribed regions replicate late. Overall, the DNA replication-timing profiles of the two different cell types are remarkably similar, with only nine regions of difference observed. In one case, this difference reflects the differential expression of an annotated gene that resides in this region. Novel transcribed regions with low coding potential exhibit a strong propensity for early DNA replication. Although the cellular function of such transcripts is poorly understood, our results suggest that their activity is linked to the replication-timing program.

Cell Differentiation↗
PubMed1998

Acute inactivation of tau has no effect on dynamics of microtubules in growing axons of cultured sympathetic neurons.

Tau is a developmentally regulated microtubule (MT)-associated protein in neurons that has been implicated in neuronal morphogenesis. On the basis of test tube studies, tau has been proposed to function in axon growth by stabilizing MTs and thereby promoting MT assembly. We have tested this hypothesis by examining the effects of acute inactivation of tau on axonal MTs. Tau was inactivated by microinjecting purified antibodies against recombinant tau into neurons before they extended axons. The injected antibodies quantitatively precipitated tau into aggregates in the soma. With these conditions the neurons elaborate normal-appearing axons, and MTs extend throughout the axons and into the growth cones, but the axons and their MTs are depleted of tau. The immunodepletion of tau had no detectable effect on several parameters of the dynamics of axonal MTs. Depletion of tau also was not accompanied by a reorganization of other major MT-associated proteins or actin filaments in these neurons. Thus, neurons effectively depleted of tau can extend axons that resemble those of control cells, and the axons contain normal-appearing MT arrays with normal dynamic behavior. These observations are exactly the opposite of those expected on the basis of the hypothesis that the stability of axonal MTs is a direct function of their content of tau, indicating that tau in growing axons of cultured sympathetic neurons is not specialized to promote microtubule assembly and stability.

Adrenergic Fibers↗
PubMedDate not supplied

On processes of peer influences in adolescent drug use: a developmental perspective.

Data from longitudinal studies of adolescents carried out over the last ten years are reviewed to provide an integrated and dynamic perspective on the nature of friendships and processes of peer influence in adolescent drug involvement, within a general developmental perspective. Four interrelated questions are examined: What individual attributes are especially important in the formation of friendships among adolescents? Which of two processes, selection or socialization, account for the similarity in values and behaviors observed in ongoing friendship dyads, and how important is similarity in friendship formation and dissolution? What is the nature of friends' influence as compared to parents', and in which domains of adolescent's life do these influences exert themselves? What mechanisms, role modeling or social learning, underlie processes of interpersonal influences? Relational dyadic and triadic samples of adolescents matched to a parent and/or a best friend and observed at one point in time as well as over time provide important and relatively rare sources of data on processes of interpersonal influence. Sociodemographic characteristics are the strongest determinants of friendship formation, with participation in illicit drugs following next in importance. Both selection (assortative pairing) and socialization contribute to observed similarity in friendship pairs. Adolescents coordinate their choice of friends and their values and behaviors, in particular the use of marijuana, so as to maximize congruency in the friendship dyad. If there is a state of unbalance such that the friend's attitude or behavior is inconsistent with the adolescent's, the adolescent will either break off the friendship and seek another friend or will keep the friend and modify his or her own behavior. Both parents and peers can have strong influences on adolescents, depending upon the arena of influence. Parents are especially important for future life plans, while peers are most important for involvement in illicit drug use. However, for drug use itself, there are different patterns of influence depending upon the stage of drug involvement. Peers are especially important for initiation into marijuana use, while parental factors gain in importance in the transition from marijuana use to the use of other illicit drugs. Interpersonal influences of peers on ongoing marijuana and alcohol use result from modeling and imitation more than from social reinforcement and the transmission of values.

Adolescent↗
PubMed2006

Maturation of luminance- and motion-defined form perception beyond adolescence: a combined ERP and fMRI study.

Abilities to discriminate forms defined by motion continue to develop throughout childhood. To investigate late development of the visual motion system, we measured brain activity with event-related EEG potentials (ERPs) and functional magnetic resonance imaging (fMRI) in groups of adolescents (15-17 years) and adults (20-30 years) during a visual form discrimination task--with forms being either defined by motion or luminance contrast. We further explored whether possible developmental changes varied with the degree of motion coherence reflecting maturation specific to global motion processing. Both the fMRI activation patterns and ERP topographies were very similar between adolescents and adults, suggesting that the basic visual networks for processing motion and form are established by the age of 15-17. The ERP response to luminance- and motion-defined forms was dominated by a posterior negativity (N1: 120-270 ms). The N1 of the motion contrast was delayed in adolescents, whereas the N1 of the static condition did not differ between groups. Since the motion-evoked N1 is thought to arise in the middle temporal area MT/V5, our results indicate that visual motion processing in MT continues to get faster, becoming still more efficient during late development. Neither the ERP nor the fMRI results revealed maturation effects specific to motion coherence. This indicates that the specific mechanisms to process global dot motion are already mature in adolescence. The present findings support the view that static perception matures earlier than dynamic perception, and that these visual systems have different developmental courses.

Adolescent↗
PubMed2004

Health-related stress, affect, and depressive symptoms experienced by caregiving mothers of adults with a developmental disability.

The interrelationships among health-related stress, positive and negative affect, and depressive symptoms patterned in the dynamic model of affect (J. Reich, A. Zautra, & M. Davis, 2003) were examined using data from 932 women having an adult child with a developmental disability. Results indicate that women experience a moderate inverse correlation between positive and negative affect under conditions of low levels of health-related stress, whereas at high levels of stress, positive and negative affect become more strongly inversely correlated. Under high-stress conditions, both negative affect and positive affect have a stronger relationship to depressive symptoms than they do under low-stress conditions.

Adolescent↗
PubMed2003

Temporal changes in the expression of brain-derived neurotrophic factor mRNA in the ventromedial nucleus of the hypothalamus of the developing rat brain.

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family, which is important for the growth, differentiation, and survival of neurons during development. We have performed a detailed mapping of BDNF mRNA in the neonatal rat brain using a quantitative in situ hybridization technique. At postnatal day (PND) 4, hypothalamic structures showed only modest expression of BDNF mRNA, with the exception of the ventromedial nucleus (VMN), where expression was higher than that detected in the hippocampus. Abundant BDNF mRNA was also found in the bed nucleus of the anterior commissure, retrosplenial granular cortex, and the posteroventral part of the medial amygdaloid nucleus. Messenger RNAs encoding other neurotrophins, including nerve growth factor (NGF) and neurotrophin-3 (NT-3) and the BDNF receptor trkB, were not selectively localized in neonatal VMN. During subsequent developmental stages, BDNF mRNA expression in the VMN changed dynamically, peaking at PND 4 and falling to minimal levels in the adult brain. In contrast, the low levels of BDNF mRNA observed in the CA3 region of the hippocampus increased to adult levels following PND 10. As the VMN undergoes sexual differentiation, we compared BDNF, NGF, NT-3, and trkB mRNA expression in the VMN in males and females at embryonic day 20 and PND 4, but found no differences between them. These results suggest that localized and high level expression of BDNF mRNA in the neonatal VMN plays an important role in its neural organization and functional development.

Aging↗
PubMedDate not supplied

[Ontogenesis and population: evaluation of developmental stability in natural populations].

Ontogenetic and population studies traditionally develop independently. At the same time, the relevance of specific analysis of a specimen as ontogenesis for both correct assessment of populations and their dynamics in time and space and understanding the mechanisms underlying population processes is becoming more and more clear. Developmental stability serves as the most general description of the developing organism status. The level of developmental noise commonly evaluated by fluctuating asymmetry is the main index of developmental stability. High developmental stability is maintained on the basis of genetic coadaptation under optimal developmental conditions. Coordinated changes in developmental stability and other homeostatic indices, including genetic, physiological, biochemical, and immune indices suggest that we consider the general status of the organism by evaluating its developmental stability. Evaluation of developmental stability as a measure of environmental stress, apparently, is the most promising. In practical terms, this allows us to evaluate and monitor environmental health under both natural and various anthropogenic conditions. Outlooks of this approach as relates to studies of developmental stability are discussed.

Adaptation, Physiological↗