Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “developmental dynamics”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

Developmental and individual differences in children's on-line representations of dynamic social events.

Developmental and clinical differences in children's on-line understanding of ongoing social events were examined. Boys with (n = 38) and without (n = 41) Attention Deficit Hyperactivity Disorder (ADHD) were compared. Prior social schemes and integrative processes were hypothesized to influence children's representation of incoming social cues. Younger children and children with ADHD were expected to differ from older children and children without ADHD, respectively, in what they encoded and how they organized the encoded information. Differences in on-line representation were postulated to underlie differences in children's recall and social reasoning. Children's prior social schemes, looking time and on-line verbal protocols, recall, and social reasoning were assessed. Younger boys and ADHD boys showed less integrated on-line representations, accounting for poorer recall and reasoning.

Age Factors↗
PubMedDate not supplied

[Dynamics and variability of early morphogenesis in the loach according to observations of individual developmental trajectories].

The dynamics and variability of quantitative morphological characters (morphological variables), which undergo changes upon epiboly, were studied by means of vital observations and measurements of developing loach (Misgurnus fossilis L.) embryos within equal time intervals. None of morphological variables, which characterize the dynamics of blastoderm shape, had monotonous dependence on time. In each individual embryo, the intervals of changes in morphological variables in the "normal" direction corresponding to the change of their mean values during the normal course of epiboly alternated with arrests, as well as with the changes of morphological variables in the reverse direction. The dynamics of morphological variables in time, which reflect the sequence of morphological states of the same embryo, and those of individual variations (variations of morphological states of different embryos on the same temporal section) had identical structure. This suggests instability of individual trajectories of morphogenesis or, strictly speaking, their actual absence. It was shown for the first time on the basis of analysis of individual trajectories of morphogenesis that its dynamics corresponded to so-called "determined chaos", which was previously discussed only as a theoretical possibility. The data obtained suggest that upon approach to the equatorial area of the embryo, the blastoderm marginal zone was elongated in the longitudinal direction and contracted across the axis of its movement. As a result, a positive feedback arises between the cooperated cell movement and the change of shape of the surface, over which the cells move. This leads, due to unstable radial symmetry of this movement, to the formation of embryonic shield.

Animals↗
PubMedDate not supplied

Exploring the dynamic background of the developmental processes and cell reactions with the use of an ultraweak photon emission.

Any reactions of the living systems are to a great extent context-dependent. Meanwhile, the biological essence of a "context" remains to be obscure. We suggest that it may be based upon an ensemble of molecular-supramolecular oscillators, which have different characteristic times. For testing this hypothesis, we applied the Fourier statistics to the time series of the records of an ultraweak photon emission (UWPE) registered from fish eggs and embryos and from cell cultures. We detected the regular changes of the UWPE Fourier spectra (FS) during embryonic development and physiological reactions of cell cultures. In many cases, such changes were going on in a holistic manner, i.e. involving broad spectral areas rather than single frequency maxims. FS of the earlier developmental stages showed greater instability and the presence of a short-range order only. On the contrary, at the advanced developmental stages a long-range order has emerged within the spectra. Another distinction of the highly organized biological samples (developing embryos, confluent fibroblasts cultures) from non-biological controls and "poorly organized" samples (non-fertilized eggs, non-confluent, poorly spread cell cultures) was the UWPE correlation dynamics which was more cooperative in highly organized samples. A non-invasive technique of UWPE registration may be useful for exploring a fluctuated oscillatory background of the developmental and physiological states of biological samples.

Animals↗
PubMed1999

The use of dynamic interventional MRI in developmental dysplasia of the hip.

Conventional methods of imaging in the investigation of developmental dysplasia of the hip all have disadvantages, either in definition or in exposure to radiation. We describe a new open-configuration MR scanner which is unique in that it allows anaesthesia and access to the patient within the imaging volume for surgical procedures and application of casts. We performed 13 scans in eight anaesthetised infants. Dynamic imaging revealed two dislocated hips which were then visualised during reduction. Hip spicas were applied without removing the patient from the scanner. In one hip, an adductor tenotomy was carried out. In all patients, stressing the hips during dynamic imaging allowed an assessment of stability. This was particularly useful in two hips in which an analysis of stability in different positions facilitated the planning of femoral osteotomies. This method of imaging provides new and important information. It has great potential in the investigation of developmental dysplasia of the hip and, with ultrasound, may allow management without the need for radiography.

Anesthesia, General↗
PubMed1998

Dynamics and ultrastructure of developmental cell fusions in the Caenorhabditis elegans hypodermis.

Cell fusions produce multinucleate syncytia that are crucial to the structure of essential tissues in many organisms [1-5]. In humans the entire musculature, much of the placenta, and key cells in bones and blood are derived from cell fusion. Yet the developmental fusion of cell membranes has never been directly observed and is poorly understood. Similarity between viral fusion proteins and recently discovered cellular proteins implies that both cell-cell and virus-cell fusion may occur by a similar mechanism [6-8]. Paradoxically, however, fusion of enveloped viruses with cells involves an opening originating as a single pore [9-11], whereas electron microscopy studies of cell-cell fusion describe simultaneous breakdown of large areas of membrane [12, 13]. Here, we have shown that developmental cell fusion is indeed consistent with initiation by a virus-like, pore-forming mechanism. We examined live cell fusions in the epithelia of Caenorhabditis elegans embryos by a new method that integrates multiphoton, confocal, and electron microscopy. The fusion aperture always originated at a single point restricted to the apical adherens junction and widened slowly as a radial wavefront. The fusing membranes dispersed by vesiculation, rather than simple unfolding of the conjoined double bilayer. Thus, in these cells fusion appears to require two specialized sequential processes: formation of a unique primary pore and expansion of the opening by radial internalization of the interacting cell membranes.

Animals↗
PubMed1983

[Congenital developmental defects in the genetic monitoring system. I. The selection of developmental defects subject to dynamic observation].

The requirements for selection of congenital malformations in the system of genetic monitoring as models have been studied. Model malformations have been shown to be easily and reliably diagnosed even in infancy. Their rate should be not less than 1:5000 births. The precise knowledge of the genetics of model forms is needed as well. Down's syndrome registration is the most convenient method for evaluation of mutations in a genome. We recommend registration in total all multiple congenital malformations (without Down's syndrome) for estimation of dominant mutability dynamics, as it was shown that more than 11% of all multiple malformations are caused by sporadic dominant mutations.

Congenital Abnormalities↗
PubMed2002

Developmental trajectories, transitions, and nonlinear dynamical systems: a model of crime deceleration and desistance.

Research on crime-related developmental trajectories is reviewed with outcomes revealing the existence of several trajectories rather than a single general pattern. Each trajectory is marked by transitions that define the pattern's path and direction over time. These anticipated transitions differ from the unanticipated transitions known to precipitate crime deceleration and desistance. Borrowing principles from nonlinear dynamical systems theory--sensitive dependence on initial conditions, chaotic attractors, and self-organization in particular--this article offers a model of crime deceleration and desistance in which belief systems congruent with crime are altered in phases--initiation, transition, maintenance--to create belief systems incongruent with crime. The practical implications of this model are discussed and suggestions for future research are outlined.

Adolescent↗
PubMed2003

Developmental modulation of retinal wave dynamics: shedding light on the GABA saga.

Embryonic spontaneous activity, in the form of propagating waves, is crucial for refining visual connections. To study what aspects of this correlated activity are instructive, we must first understand how their dynamics change with development and what factors trigger their disappearance after birth. Here we report that in the turtle retina, GABA, rather than glutamate and acetylcholine, influences developmental changes in wave dynamics. Using calcium imaging of the ganglion cell layer, we report how waves switch from fast and broad, when they emerge, to slow and narrow a few days before hatching, coinciding with the emergence of excitatory GABA(A) receptor-mediated activity. Around hatching, waves gradually become stationary patches, whereas GABA(A) shifts from excitatory to inhibitory, coinciding with the upregulation of the cotransporter KCC2, suggesting that changes in intracellular chloride underlie the shift. Dark-rearing from hatching causes correlated spontaneous activity to persist, whereas GABA(A) responses remain excitatory, and KCC2 expression is weaker. We conclude that GABA plays an important regulatory role during the maturation of retinal neural activity. Using a simple and elegant mechanism, namely the switch from excitatory to inhibitory, GABA(A) receptor-mediated activity is necessary and sufficient to cause retinal waves to stop propagating, ultimately leading to the disappearance of correlated spontaneous activity. Moreover, our results suggest that visual experience modulates the GABAergic switch.

Action Potentials↗
PubMed2005

The evolution of paternal identity in late adulthood.

The experience of fatherhood in late adulthood has received little attention in the psychoanalytic literature. After a presentation of the literature on fatherhood and a consideration of the developmental tasks of late adulthood in which the experience of fatherhood is embedded, the dynamically charged, developmentally conflicted nature of the relationships between late-life fathers and their children is explored. A basic premise is that the changing nature of these relationships inevitably confronts the elderly patriarch with considerable intra-psychic turmoil, reflection, and conflict that must be engaged and mastered if these most significant relationships are to be maintained and sustained for both generations. Clinical examples illustrate the theoretical points presented.

Adult↗
PubMed2001

Development of memory for pattern and path: further evidence for the fractionation of visuo-spatial memory.

Evidence from a number of sources now suggests that the visuo-spatial sketchpad (VSSP) of working memory may be composed of two subsystems: one for maintaining visual information and the other for spatial information. In this paper we present three experiments that examine this fractionation using a developmental approach. In Experiment 1, 5-, 8-, and 10-year old children were presented with a visuo-spatial working memory task (the matrices task) with two presentation formats (static and dynamic). A developmental dissociation in performance was found for the static and dynamic conditions of both tasks, suggesting that the activation of separable subsystems of the VSSP is dependent upon a static/dynamic distinction in information content rather than a visual/spatial one. A highly similar pattern of performance was found for a mazes task with static and dynamic formats. However, one strategic activity, the use of simple verbal recoding, may also have been responsible for the observed pattern of performance in the matrices task. In Experiments 2 and 3 this was investigated using concurrent articulatory suppression. No evidence to support this notion was found, and it is therefore proposed that static and dynamic visuo-spatial information is maintained in working memory by separable subcomponents of the VSSP.

Child↗
PubMed1991

The dynamics of bimanual coordination in developmental dyslexia.

The temporal organization of symmetric and asymmetric bimanual coordination tasks was compared between dyslexic adults and normally reading controls by means of a dynamical systems research strategy. Both groups demonstrated the influence of the intrinsic dynamics of rhythmic motor behavior on the performance of asymmetric bimanual tasks. In normal readers, manual asymmetries of motor control had a significant effect on the relative phasing of finger movements; no such effects were observed in dyslexic subjects. Group differences are discussed in terms of the interaction between neurological constraints and dynamic principles of spontaneous pattern formation.

Adolescent↗
PubMed2002

Dynamic magnetic resonance guided treatment of developmental dysplasia of the hip.

This study demonstrates the feasibility and advantages of near real-time, multiplanar, dynamic magnetic resonance image-assisted treatment of patients with developmental dysplasia of the hip. Pathoanatomy and dynamic blocks to reduction are visualized with anatomic clarity not otherwise possible. Continuous imaging allows accurate assessment and maintenance of optimum positioning throughout the casting procedure. Patient charges for this new technique are less than standard methods of treatment, and the child receives no ionizing radiation.

Arthrography↗
PubMedDate not supplied

The promise of dynamic systems approaches for an integrated account of human development.

After decades of theoretical fragmentation and insularity, a converging explanatory framework based on general scientific principles is an important goal for developmental psychology. Dynamic systems approaches may provide such a framework, using principles of self-organization to explain how novel forms emerge without predetermination and become increasingly complex with development. New trends in traditional theoretical families emphasize systemic, emergent processes, and these can now be explicated with principles of self-organization that apply to all natural systems. Self-organization thus provides a single explanation for the multiple facets of development, integrating diverse developmental viewpoints within a larger scientific perspective.

Cognition↗
PubMed2005

Developmental changes in shoot N dynamics of lucerne (Medicago sativa L.) in relation to leaf growth dynamics as a function of plant density and hierarchical position within the canopy.

Shoot N concentration in plants decreases as they get bigger, due to the fact that N accumulates less rapidly than dry matter in plants during the plant growth process, leading to an allometric relationship between shoot N content (N(sh)) and shoot mass (W(sh)): N(sh)=a(W(sh))b. The results obtained on lucerne plants growing either under controlled low density conditions or in dense stands under field conditions show that the value of the allometric coefficient b that represents the ratio between the relative N accumulation rate in shoots [dN(sh)/(N(sh)dt)] and the relative growth rate [dW(sh)/(W(sh)dt)], decreases from 0.88 for a low plant density to 0.72 for a dense stand. Therefore, the fractional increase of shoot N per unit of shoot dry matter is lower when plants are in competition for light in dense canopies. This decrease can be entirely explained by the parallel decline in the leaf area per unit of shoot mass. Thus, a remarkably constant linear relationship can be established between N(sh) and leaf area (LA): N(sh)=1.7 g m(-2) LA, regardless of the conditions (low versus high density, controlled versus field conditions). Moreover, in a field dense stand, the comparison of plants with contrasting positions between the top and the bottom of the canopy (dominant, intermediate or suppressed plants), also shows that the difference in N(sh) at similar shoot mass is explained by the proportion of leaf mass to shoot mass. These data support the idea that leaf growth drives the dynamics of shoot N accumulation. These results also indicate that competition for light among individual plants within a dense canopy induces developmental changes in plant morphology (leaf:stem ratio) that explain the differences observed in shoot N concentration. This last observation could be extrapolated to multi-specific plant stands. Therefore, the sharing of N resources among plant species could partially be the result of the sharing of light within the canopy.

Light↗
PubMed2005

The innovation triad: an EvoDevo agenda.

This article introduces a special issue on evolutionary innovation and morphological novelty, two interrelated themes that have received a remarkable increase of attention over the past few years. We begin with a discussion of the question of whether innovation and novelty represent distinct evolutionary problems that require a distinct conceptualization. We argue that the mechanisms of innovation and their phenotypic results--novelty--can only be properly addressed if they are distinguished from the standard evolutionary themes of variation and adaptation, and we present arguments for making such a distinction. We propose that origination, the first formation of biological structures, is another distinct problem of morphological evolution, and that together with innovation and novelty it constitutes a conceptual complex we call the innovation triad. We define a problem agenda of the triad, which separates the analysis of the initiating conditions from the mechanistic realization of innovation, and we discuss the theoretical problems that arise from treating innovation as distinct from variation. Further, we categorize the empirical approaches that address themes of the innovation triad in recognizing four major strands of research: the morphology and systematics program, the gene regulation program, the epigenetic program, and the theoretical biology program. We provide examples of each program, giving priority to contributions in the present issue. In conclusion, we observe that the innovation triad is one of the defining topics of EvoDevo research and may represent its most pertinent contribution to evolutionary theory. We point out that an inclusion of developmental systems properties into evolutionary theory represents a shift of explanatory emphasis from the external factors of natural selection to the internal dynamics of developmental systems, complementing adaptation with emergence, and contingency with inherency.

Adaptation, Physiological↗
PubMed1999

The future of the fossil record.

The fossil record provides a powerful basis for analyzing the controlling factors and impact of biological evolution over a wide range of temporal and spatial scales and in the context of an evolving Earth. An increasingly interdisciplinary paleontology has begun to formulate the next generation of questions, drawing on a wealth of new data, and on methodological advances ranging from high-resolution geochronology to simulation of morphological evolution. Key issues related to evolutionary biology include the biotic and physical factors that govern biodiversity dynamics, the developmental and ecological basis for the nonrandom introduction of evolutionary innovations in time and space, rules of biotic response to environmental perturbations, and the dynamic feedbacks between life and the Earth's surface processes. The sensitivity of evolutionary processes to rates, magnitudes, and spatial scales of change in the physical and biotic environment will be important in all these areas.

Animals↗
PubMed2006

Enhancement of veratridine-induced sodium dynamics in NG108-15 cells during differentiation.

Developmental changes in dynamics of Na+ were studied in neuroblastomaxglioma hybrid NG108-15 cells during differentiation which was induced by dibutyryl cAMP (Bt2cAMP). Ratiometric Na+ imaging with a Na+-sensitive fluorescent dye SBFI (sodium-binding benzofuran isophthalate) revealed that the intracellular Na+ concentration ([Na+]i) was not affected by the application of high K+ (60 mM) solution to either control or differentiated cells. When cells were exposed to 50 microM veratridine (Vtd), an agonist of voltage-sensitive sodium channels (VSSCs), a significant increase in [Na+]i was observed in differentiated but not in undifferentiated cells. Calculated mean [Na+]i value increased from the basal 10.4 to 44.1 mM in response to 50 microM Vtd. This Vtd response was reversibly inhibited by tetrodotoxin (TTX), a specific blocker for VSSCs, in a dose-dependent manner (IC50 = 1 nM). It is suggested that VSSCs in NG108-15 cells are sensitive to TTX and Vtd and that the number of VSSCs increases during differentiation.

Benzofurans↗
PubMed1996

The developmental origins of bimanual coordination: a dynamic perspective.

Patterns of interlimb coordination associated with infant reaching fluctuate frequently over developmental time. This study investigated whether these fluctuations are related to coordination tendencies. Interlimb patterns were studied in reaching and nonreaching movements in 4 infants, which were followed through their 1st year. Each week, reaching and nonreaching endpoint kinematics were recorded in both arms during multiple 14-s trials. It was found that patterns of interlimb coordination in reaching matched coordination tendencies in nonreaching. Reaching fluctuated between uni- and bimanual periods. During the bimanual periods, nonreaching interlimb activity tended to be synchronous. During the unimanual periods, nonreaching activity revealed no predominant form of interlimb coordination. It is argued that changing coordination tendencies may influence the organization of specific goal-oriented behaviors from early in life.

Female↗