Properties In Children Research Articles

Impact of videogame play on the brain's microstructural properties: cross-sectional and longitudinal analyses.

Videogame play (VGP) has been associated with numerous preferred and non-preferred effects. However, the effects of VGP on the development of microstructural properties in children, particularly those associated with negative psychological consequences of VGP, have not been identified to date. The purpose of this study was to investigate this issue through cross-sectional and longitudinal prospective analyses. In the present study of humans, we used the diffusion tensor imaging mean diffusivity (MD) measurement to measure microstructural properties and examined cross-sectional correlations with the amount of VGP in 114 boys and 126 girls. We also assessed correlations between the amount of VGP and longitudinal changes in MD that developed after 3.0±0.3 (s.d.) years in 95 boys and 94 girls. After correcting for confounding factors, we found that the amount of VGP was associated with increased MD in the left middle, inferior and orbital frontal cortex; left pallidum; left putamen; left hippocampus; left caudate; right putamen; right insula; and thalamus in both cross-sectional and longitudinal analyses. Regardless of intelligence quotient type, higher MD in the areas of the left thalamus, left hippocampus, left putamen, left insula and left Heschl gyrus was associated with lower intelligence. We also confirmed an association between the amount of VGP and decreased verbal intelligence in both cross-sectional and longitudinal analyses. In conclusion, increased VGP is directly or indirectly associated with delayed development of the microstructure in extensive brain regions and verbal intelligence.

Limited microstructural and connectivity deficits despite subcortical volume reductions in school-aged children born preterm with very low birth weight

Preterm birth and very low birth weight (VLBW, ≤1500g) are worldwide problems that burden survivors with lifelong cognitive, psychological, and physical challenges. In this multimodal structural magnetic resonance imaging (MRI) and diffusion MRI (dMRI) study, we investigated differences in subcortical brain volumes and white matter tract properties in children born preterm with VLBW compared to term-born controls (mean age=8years). Subcortical brain structure volumes and cortical thickness estimates were obtained, and fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were generated for 18 white matter tracts. We also assessed structural relationships between white matter tracts and cortical thickness of the tract endpoints. Compared to controls, the VLBW group had reduced volumes of thalamus, globus pallidus, corpus callosum, cerebral white matter, ventral diencephalon, and brain stem, while the ventricular system was larger in VLBW subjects, after controlling for age, sex, IQ, and estimated total intracranial volume. For the dMRI parameters, group differences were not significant at the whole-tract level, though pointwise analysis found shorter segments affected in forceps minor and left superior longitudinal fasciculus – temporal bundle. IQ did not correlate with subcortical volumes or dMRI measures in the VLBW group. While the deviations in subcortical volumes were substantial, there were few differences in dMRI measures between the two groups, which may reflect the influence of advances in perinatal care on white matter development.

An Enduring Relic: Family Law Reform and the Inflexibility of <I>Wilāya</I>

This Article discusses the rules governing guardianship over a child’s property and personal affairs in contemporary Muslim jurisdictions from a comparative perspective. Specifically, it questions the reasons for a less progressive reading and interpretation of wilāya (guardianship) in an era that has otherwise borne witness to family law codification and reform in the majority of Arab-Muslim countries. The Article first considers the legislatures’ reluctance to reform guardianship despite having adopted a progressive approach for other areas of family law in general and for custody, as an element of the parent—child relationship, in particular. It then classifies the current guardianship rules that can be found in (Arab) Muslim jurisdictions and concludes that, apart from the Maghreb, wilāya is still framed as a largely gendered legal concept and a male prerogative. Finally, these legislative choices are discussed with a view to potential reform impediments, namely a patriarchal reading of pre-modern Islamic legal doctrine, the legislatures— preference for vesting financial control in men, and, lastly, the outsourcing of guardianship from the larger body of codified family law as can be witnessed in some jurisdictions. The Article concludes that, in addition to relying on pre-modern legal practice, changes in current guardianship rules can be equally brought about through an inter-Arab comparative approach to family law reform as well as an adjustment of wilāya to the themes and leitmotifs already permeating most codified family law in contemporary Muslim jurisdictions.

Short health scale: a valid, reliable, and responsive measure of health-related quality of life in children with inflammatory bowel disease.

Inflammatory bowel disease (IBD) presents a growing medical and epidemiological problem. In respect to patients, health-related quality of life (HRQOL) emerged as informative means to evaluate the impact of disease burden on health. The Short Health Scale (SHS), a disease-specific HRQOL instrument with only 4 questions (symptoms, functioning, worry, and general well-being), was demonstrated as valid, reliable, and responsive in adults. Aim of this study was to assess its psychometric properties in children with IBD. In a multicentric prospective study, HRQOL was assessed in 104 children with IBD by generic (PedsQL) and disease-specific questionnaires (IMPACT-III (HR) and SHS), which were cross-culturally adapted for Croatian. Forty-one patients completed the questionnaires at the second visit 6 to 12 months later. Of them, 27 patients changed from remission to active disease or vice versa and were included in responsiveness to change analysis. Patients in remission had significantly better scores for symptoms (P = 0.022) and functioning (P = 0.003) than those with active disease. Each of the 4 SHS questions was strongly correlated with the corresponding dimensions of PedsQL and IMPACT-III (HR) questionnaires (rs = 0.50-0.72, P < 0.001). Reliability was confirmed with Cronbach's α = 0.74. Patients who changed from remission to active disease or vice versa showed significant change in following SHS scores: symptoms (P = 0.032), functioning (P = 0.008), and worry (P = 0.021). SHS appears to be valid, reliable, and responsive tool to measure HRQOL in children with IBD. Simplicity of use, compactness, and the possibility of immediate interpretation make SHS well suited for both clinical practice and research studies.

Проблемы развития детского социального туризма в Крыму

In this article the authors present concept of shared children&amp;#180;s tourism and children&amp;#180;s social tourism, considered systemic problems in the functioning of children&amp;#180;s sanatorium and health institutions of the Crimea. First, the authors provided a retrospective analysis of the formation and the scope of children&amp;#180;s social tourism in Crimea how the economic transformation is conducted in provision of social support for children&amp;#180;s health in a command and market economic systems. Substantiated are the factors affecting the crisis state of institutions of child health improvement: the processes of privatization of property of children&amp;#180;s health institutions, lack of budget financing of government programs to improve the health of children from socially disadvantaged groups, the decline in the quality of children&amp;#180;s health. The article highlights directions of the long-term prospects for the development of children&amp;#180;s health resorts of Crimea related to the development of children&amp;#180;s tourism in the tourism industry in Russia. As in the federal programme of support for rehabilitation of children argued, there should be the establishment of the state order for recreation system and financial support for children&amp;#180;s health institutions. The authors note trends in the development of children&amp;#180;s health centers of Crimea in the following directions: wider specialization, existing health centers, taking into account changes in the structure of child populations, comprehensive treatment. To create control systems of functioning and development for the recreational and tourist complex, which are formed within the administrative-territorial formations, there should be introduced the following elements: resource componentsof recreational potential (natural, human, financial, material, technological, informational), organizational and legal support of the form of ownership in the recreation and tourism complex, including the relationship arising in the course of ownership, management, exchange of different categories of resources, state regulation of processes in the system of children&amp;#180;s health institutions.

Resistance training in children.

Children develop lower levels of muscle force, and at slower rates, than adults. Although strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strain- related tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (age 8.9 ± 0.3 yr) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a l0-week RT intervention consisting of 2–3 sets of 8–15 plantar flexion contractions performed twice weekly on a recumbent calf-raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness, and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve), and rate of electromyographic (EMG) increase (REI; slope of the EMG time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively; not significant) which may have implications for tendon injury risk and muscle fiber mechanics. A decrease of ~13% in EMD was found after RT for the experimental group, which paralleled the increase in tendon stiffness (r = −0.59); however, RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of importance within the context of the efficiency and execution of movement.

Biomechanics and exercise.

Children develop lower levels of muscle force, and at slower rates, than adults. While strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strainrelated tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (8.9 ± 0.3 years) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-week RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice weekly on a recumbent calf raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve) and rate of EMG increase (REI; slope of the EMG-time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively, n.s) which may have implications for tendon injury risk and muscle fiber mechanics. A ~13% decrease in EMD was found after RT for the experimental group which paralleled the increase in tendon stiffness (r = −0.59), however RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of potential importance within the context of the efficiency and execution of movement.

Aortic Elastic Properties in Children with Type 1 Diabetes

Aortic Elastic Properties in Children with Type 1 Diabetes

Endothelial Function and Vascular Properties in Children with Sickle Cell Disease.

Sickle cell disease (SCD) is an inherited disorder characterized by recurrent painful crises with ischemia resulting from vascular occlusion. Adults with SCD have increased arterial stiffness and reduced flow-mediated dilation (FMD), due to impaired release of substances such as nitric oxide. We aimed to assess the vascular properties of carotid and brachial arteries in children with SCD compared with a control group without cardiovascular risk factors. Thirty patients with SCD, mean age 12.3±4.5years, were prospectively enrolled. A control group was made up of 30 age- and gender-matched healthy subjects. Carotid intima-media thickness (IMT), cross-sectional compliance (CSC), cross-sectional distensibility (CSD), diastolic wall stress (DWS), incremental elastic modulus (Einc), and FMD were determined in both groups. There was no significant difference in FMD between the two groups (8.2±5.0% in the SCD group vs. 9.3±4.2% in the control group, P=0.15). There was no significant correlation between FMD and age, hemoglobin, LDH level, or transcranial Doppler findings. CSD was significantly elevated in the SCD group (0.96±0.44 vs. 0.59±0.21, P=0.0002), whereas DWS and Einc were significantly lower in the SCD group. CSC did not differ significantly between the two groups. Children with SCD have no marked endothelial dysfunction or change in arterial stiffness. These manifestations may be related to disease severity and duration. Changes may become evident later in life as the disease progresses.

Abstract 19684: Abnormal Aortic Wall Properties in Children with Isolated Bicuspid Aortic Valve

Introduction: Abnormal aortic wall properties have been reported in patients with isolated bicuspid aortic valve (IBAV) even in the absence of significant aortic stenosis or regurgitation. Hypothesis: We sought to assess aortic distensibility (DIS) and stiffness index (SI) in children with IBAV compared to age group-matched subjects with normal tricuspid aortic valves (TAV) and to determine whether these abnormalities in the aortic wall properties correlate with bicuspid valve morphology or left ventricular systolic or diastolic function. Methods: Children ages 8-18 years with an IBAV and age group-matched controls with a TAV were prospectively enrolled. Subjects with greater than mild stenosis or mild regurgitation were excluded. Using echo, aortic valve morphology, aortic root (AoR) and ascending aorta (AAo) diameters and z-scores were determined. Left ventricular shortening fraction (LVSF), DIS and SI were measured using M-mode echo. Diastolic function was determined using mitral valve septal E/Ea. Blood pressure (BP) was measured at the time of echo. Results: Nineteen had IBAV and 17 had TAV. There were no significant differences in age, weight, height or BP between the two groups. In the IBAV group, 11 had right-left type (R/L) and 8 had right-non type (R/N). There was no significant difference in AoR z-scores between groups. The IBAV group had larger AAo z-scores (2.48±1.9 vs. -0.02±0.98, p&lt;0.0001), decreased DIS (9.6±4 vs. 12.3±3.1 cm2 dynes-1 x 10-6, p&lt;0.05) and increased SI (21.4±9.2 vs. 14.4±3.8, p=0.007) compared to the TAV group. There were no differences in these variables between the R/L or R/N subgroups. No correlation was seen between aortic wall properties and ventricular function in the IBAV group. By multivariate regression, presence of an IBAV (coefficient = -2.4, p=0.03), LVSF (coefficient = -0.35, p=0.01) and age-adjusted systolic BP (coefficient = -0.13, p=0.03) were independently associated with DIS. Similarly, presence of an IBAV (coefficient = 6.7, p=0.005) and age (coefficient=0.85, p=0.02) were independently associated with SI. Conclusions: Children with IBAV have decreased DIS and SI even without hemodynamic abnormalities. Long-term studies to determine the impact of these findings on cardiovascular risk are needed.

Arterial remodeling and its relationship with blood pressure control in children with non-dialysis chronic kidney disease

Objectives: To investigate large artery viscoelastic properties in children with non-dialysis stages of CKD and compare these with healthy children with normal renal function and (ii) to evaluate the impact of blood pressure components following adjustment for level of renal dysfunction. Methods: Prospective single centre study including 226 children [188 children with non-dialysis CKD (11.9 3.7 years) and 38 controls (11.5 3.3 years)] were recruited from tertiary out-patient clinics. Common carotid artery parameters were non-invasively determined using a high-definition echotracking system. Peripheral and central BP were also measured noninvasively. Results: When compared to controls, in children with CKD with similar levels of peripheral and central BP, anatomical measures of arterial properties such as lumen diameter and carotid wall thickness remained comparable. In those with BP >75th percentile there were significant differences between elastic properties of the carotid artery when compared with controls: distensibility (92 31 versus 114 33 kPa-1 x 103, pZ0.03), compliance (2.1 0.7 versus 2.6 0.7 m2 kPa-1 x 106, pZ0.02), Young’s elastic modulus (0.151 0.068 versus 0.109 0.049 kPa x 10-3, pZ0.02) and wall stress (83.6 23.5 versus 68.7 14.9 kPa, pZ0.02). These differences were independent of glomerular filtration rate (GFR). Multivariate regression analyses displayed brachial mean arterial pressure (MAP), carotid systolic and carotid pulse pressure were all associated with carotid artery functional elasticity following adjustment for age, body mass index and GFR. Conclusions: Changes in elasticity of the carotid artery is one of the earliest identifiable alterations in children with non-dialysis CKD but is primarily explained by level of blood pressure and not that of renal function.

Effects of resistance training on tendon mechanical properties and rapid force production in prepubertal children.

Children develop lower levels of muscle force, and at slower rates, than adults. Although strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strain-related tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (age 8.9 ± 0.3 yr) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-wk RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice weekly on a recumbent calf-raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness, and Young's modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve), and rate of electromyographic (EMG) increase (REI; slope of the EMG time curve) were measured before and after RT. Tendon stiffness and Young's modulus increased significantly after RT in the experimental group only (∼29% and ∼25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively; not significant) which may have implications for tendon injury risk and muscle fiber mechanics. A decrease of ∼13% in EMD was found after RT for the experimental group, which paralleled the increase in tendon stiffness (r = -0.59); however, RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of importance within the context of the efficiency and execution of movement.

Dalhousie Dyspnea and Perceived Exertion Scales: Psychophysical properties in children and adolescents

Children and adolescents vary widely in their perception of, or capacity to rate, sensations during exercise using the Borg scale. We sought to measure sensory-perceptual responses obtained using Dalhousie Dyspnea and Perceived Exertion Scales in 79 pediatric subjects during maximal exercise challenge and to determine the psychophysical function relationship(s). Concurrent validity was assessed by canonical plots of mean ratings on either scale, which showed showing very good correlations for perceived leg exertion vs work, and dyspnea vs ventilation. Both scales yielded similar results with respect to goodness of fit regardless of whether data was fitted to a power or quadratic function provided a delay term was included. The quadratic model fixed the exponent of the power law at 2 but, unlike a power model, allowed characterization of individual responses that increased and then plateaued. Dalhousie Dyspnea and Perceived Exertion Scales offer an alternative to Borg scale during exercise in pediatric populations.

Corneal properties in children with congenital isolated growth hormone deficiency.

To compare the corneal parameters of children with congenital isolated growth hormone deficiency and healthy subjects. In this cross-sectional, prospective study, 50 cases with growth hormone (GH) deficiency treated with recombinant GH and 71 healthy children underwent a complete ophthalmic examination. The corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were measured with the Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was measured by a ultrasonic pachymeter. The mean age was 13.0±3.0 years in the GH deficiency group consisting of 21 females and 29 males and 13.4±2.4 years in the healthy children group consisting of 41 females and 30 males. There was no statistically significant difference between the groups for gender or age (Chi-square test, P=0.09; independent t-test, P=0.28, respectively). The mean duration of recombinant GH therapy was 3.8±2.4y in the study group. The mean CH, CRF, IOPg and IOPcc values were 11.0±2.0, 10.9±1.9, 15.1±3.3, and 15.1±3.2 mm Hg respectively in the study group. The same values were 10.7±1.7, 10.5±1.7, 15.2±3.3, and 15.3±3.4 mm Hg respectively in the control group. The mean CCT values were 555.7±40.6, 545.1±32.5 µm in the study and control groups respectively. There was no statistically significant difference between the two groups for CH, CRF, IOPg, IOPcc measurements or CCT values (independent t-test, P=0.315, 0.286, 0.145, 0.747, 0.13 respectively). Our study suggests that GH deficiency does not have an effect on the corneal parameters and CCT values. This observation could be because of the duration between the beginning of disease and the diagnosis and beginning of GH therapy.

Corneal biomechanical characteristics in children with diabetes mellitus

To compare the corneal biomechanical properties in children with type 1 diabetes mellitus (DM) and healthy children. In this cross-sectional study, the study and control groups were composed of 68 children with DM and 74 healthy children, respectively. The corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were measured with the ocular response analyzer (ORA). Associations between ocular and diabetic parameters were also evaluated. There were no statistically significant differences between the two groups in age or gender distribution. The mean CH was 10.8 ± 1.5 and 10.7 ± 1.7 mmHg while the mean CRF was 10.9 ± 1.9 and 10.5 ± 1.6 mmHg in the diabetic group and control group, respectively. The mean IOPg was 15.9 ± 3.7 and 15.2 ± 3.4 mmHg, and the mean IOPcc was 15.8 ± 3.0 and 15.3 ± 3.4 mmHg in the diabetic and control group, respectively. There were no statistically significant differences between the two groups for CH, CRF, IOPg, and IOPcc measurements (independent t test, p = 0.624, p = 0.207, p = 0.263, p = 0.395, respectively). This study shows that type 1 DM does not have any effect on the corneal biomechanical parameters in childhood.

In vitro ultrasonic and mechanic characterization of the modulus of elasticity of children cortical bone

The assessment of elastic properties in children’s cortical bone is a major challenge for biomechanical engineering community, more widely for health care professionals. Even with classical clinical modalities such as X-ray tomography, MRI, and/or echography, inappropriate diagnosis can result from the lack of reference values for children bone. This study provides values for elastic properties of cortical bone in children using ultrasonic and mechanical measurements, and compares them with adult values. 18 fibula samples from 8 children (5–16years old, mean age 10.6years old ±4.4) were compared to 16 fibula samples from 3 elderly adults (more than 65years old). First, the dynamic modulus of elasticity (Edyn) and Poisson’s ratio (ν) are evaluated via an ultrasonic method. Second, the static modulus of elasticity (Esta) is estimated from a 3-point microbending test. The mean values of longitudinal and transverse wave velocities measured at 10MHz for the children’s samples are respectively 3.2mm/μs (±0.5) and 1.8mm/μs (±0.1); for the elderly adults’ samples, velocities are respectively 3.5mm/μs (±0.2) and 1.9mm/μs (±0.09). The mean Edyn and the mean Esta for the children’s samples are respectively 15.5GPa (±3.4) and 9.1GPa (±3.5); for the elderly adults’ samples, they are respectively 16.7GPa (±1.9) and 5.8GPa (±2.1). Edyn, ν and Esta are in the same range for children’s and elderly adults’ bone without any parametric statistical difference; a ranking correlation between Edyn and Esta is shown for the first time.

Increased Regional Deformation of the Left Ventricle in Normal Children With Increased Body Mass Index: Implications for Future Cardiovascular Health

The prevalence of obesity continues to increase in the developing world. The effects of obesity on the cardiovascular system include changes in systolic and diastolic function. More recently obesity has been linked with impairment of longitudinal myocardial deformation properties in children. We sought to determine the effect of increased body mass index (BMI) on cardiac deformation in a group of children taking part in the population-based Southampton Women's Survey to detect early cardiovascular changes associated with increasing BMI before established obesity. Sixty-eight children at a mean age of 9.4years old underwent assessment of longitudinal myocardial deformation in the basal septal segment of the left ventricle (LV) using two-dimensional speckle tracking echocardiography. Parameters of afterload and preload, which may influence deformation, were determined from cardiac magnetic resonance imaging. BMI was determined from the child's height and weight at the time of echocardiogram. Greater pediatric BMI was associated with greater longitudinal myocardial deformation or strain in the basal septal segment of the LV (β=1.6, p<0.001); however, this was not related to contractility or strain rate in this part of the heart (β=0.001, p=0.92). The end-diastolic volume of the LV increased with increasing BMI (β=3.93, p<0.01). In young children, regional deformation in the LV increases with increasing BMI, whilst normal contractility is maintained. This effect may be explained by the increased preload of the LV associated with increased somatic growth. The long-term implications of this altered physiology need to be followed-up.

Turkish Children's Conversational Oppositions: Usage of Two Discourse Markers

This study examined how Turkish-speaking preschoolers displayed oppositions in their peer interactions through two adversative discourse markers, ya and ki. These two markers differ in their syntactic mobility. The data came from seminaturalistic peer interactions of 78 preschoolers. The discursive properties of children's utterances with ya and ki were quantitatively and qualitatively analyzed. The analyses suggested that due to the differences in their syntactic mobility, these two discourse markers flagged alternative types of oppositions. Ki, the less mobile marker, was more tightly linked to the propositional content and challenged the relevance of the prior utterance, rather than directly disagreeing with it. Such uses minimized opposition. On the other hand, ya, the more mobile marker, was semantically more independent of the proposition to which it was attached and marked opposition at a more global level. Ya-utterances were mostly in the form of counters, such as ‘Ya stop!’ – ‘Ya stop!’, which escalated conflicts.

MEG Correlates of Learning Novel Objects Properties in Children

Learning the functional properties of objects is a core mechanism in the development of conceptual, cognitive and linguistic knowledge in children. The cerebral processes underlying these learning mechanisms remain unclear in adults and unexplored in children. Here, we investigated the neurophysiological patterns underpinning the learning of functions for novel objects in 10-year-old healthy children. Event-related fields (ERFs) were recorded using magnetoencephalography (MEG) during a picture-definition task. Two MEG sessions were administered, separated by a behavioral verbal learning session during which children learned short definitions about the “magical” function of 50 unknown non-objects. Additionally, 50 familiar real objects and 50 other unknown non-objects for which no functions were taught were presented at both MEG sessions. Children learned at least 75% of the 50 proposed definitions in less than one hour, illustrating children's powerful ability to rapidly map new functional meanings to novel objects. Pre- and post-learning ERFs differences were analyzed first in sensor then in source space. Results in sensor space disclosed a learning-dependent modulation of ERFs for newly learned non-objects, developing 500–800 msec after stimulus onset. Analyses in the source space windowed over this late temporal component of interest disclosed underlying activity in right parietal, bilateral orbito-frontal and right temporal regions. Altogether, our results suggest that learning-related evolution in late ERF components over those regions may support the challenging task of rapidly creating new semantic representations supporting the processing of the meaning and functions of novel objects in children.

Evaluation of the elastic modulus of cortical bone: adaptation of experimental protocols to small samples

Properties of bone vary by successive stages from juvenile to mature state. We have very little information on the mechanical properties of children's bones and the few studies actually incurred ar...