Understanding the organization of the cerebral cortex remains a central focus of neuroscience. Cortical maps have relied almost exclusively on the examination of postmortem tissue to construct ...structural, architectonic maps. These maps have invariably distinguished between areas with fewer discernable layers, which have a less complex overall pattern of lamination and lack an internal granular layer, and those with more complex laminar architecture. The former includes several agranular limbic areas, and the latter includes the homotypical and granular areas of association and sensory cortex. Here, we relate these traditional maps to developmental data from noninvasive neuroimaging. Changes in cortical thickness were determined in vivo from 764 neuroanatomic magnetic resonance images acquired longitudinally from 375 typically developing children and young adults. We find differing levels of complexity of cortical growth across the cerebrum, which align closely with established architectonic maps. Cortical regions with simple laminar architecture, including most limbic areas, predominantly show simpler growth trajectories. These areas have clearly identified homologues in all mammalian brains and thus likely evolved in early mammals. In contrast, polysensory and high-order association areas of cortex, the most complex areas in terms of their laminar architecture, also have the most complex developmental trajectories. Some of these areas are unique to, or dramatically expanded in primates, lending an evolutionary significance to the findings. Furthermore, by mapping a key characteristic of these development trajectories (the age of attaining peak cortical thickness) we document the dynamic, heterochronous maturation of the cerebral cortex through time lapse sequences ("movies").
While there has been considerable concern over possible adverse effects of psychostimulants on brain development, this issue has not been examined in a prospective study. The authors sought to ...determine prospectively whether psychostimulant treatment for attention deficit hyperactivity disorder (ADHD) was associated with differences in the development of the cerebral cortex during adolescence.
Change in cortical thickness was estimated from two neuroanatomic MRI scans in 43 youths with ADHD. The mean age at the first scan was 12.5 years, and at the second scan, 16.4 years. Nineteen patients not treated with psychostimulants between the scans were compared with an age-matched group of 24 patients who were treated with psychostimulants. Further comparison was made against a template derived from 620 scans of 294 typically developing youths without ADHD.
Adolescents taking psychostimulants differed from those not taking psychostimulants in the rate of change of the cortical thickness in the right motor strip, the left middle/inferior frontal gyrus, and the right parieto-occipital region. The group difference was due to more rapid cortical thinning in the group not taking psychostimulants (mean cortical thinning of 0.16 mm/year SD=0.17, compared with 0.03 mm/year SD=0.11 in the group taking psychostimulants). Comparison against the typically developing cohort without ADHD showed that cortical thinning in the group not taking psychostimulants was in excess of age-appropriate rates. The treatment groups did not differ in clinical outcome, however.
These findings show no evidence that psychostimulants were associated with slowing of overall growth of the cortical mantle.
ABSTRACT We present a sample of 27 gamma-ray bursts (GRBs) with detailed Swift light curves supplemented by late-time Chandra observations. To answer the missing jet-break problem in general, we ...develop a numerical-simulation-based model that can be directly fit to the data using Monte Carlo methods. Our numerical model takes into account all the factors that can shape a jet break: (i) lateral expansion, (ii) edge effects, and (iii) off-axis effects. Our results provide improved fits to the light curves and constraints on physical parameters. More importantly, our results suggest that off-axis effects are important and must be included in interpretations of GRB jet breaks.
Parents play an important role in providing their children with social support for healthy eating and physical activity. However, different types of social support (e.g., instrumental, emotional, ...modeling, rules) might have different results on children's actual behavior. The purpose of this study was to assess the association of the different types of social support with children's physical activity and eating behaviors, as well as to examine whether these associations differ across racial/ethnic groups.
We surveyed 1169 low-income, ethnically diverse third graders and their caregivers to assess how children's physical activity and eating behaviors (fruit and vegetable and sugar-sweetened beverage intake) were associated with instrumental social support, emotional social support, modeling, rules and availability of certain foods in the home. We used sequential linear regression to test the association of parental social support with a child's physical activity and eating behaviors, adjusting for covariates, and then stratified to assess the differences in this association between racial/ethnic groups.
Parental social support and covariates explained 9-13% of the variance in children's energy balance-related behaviors. Family food culture was significantly associated with fruit and vegetable and sugar-sweetened beverage intake, with availability of sugar-sweetened beverages in the home also associated with sugar-sweetened beverage intake. Instrumental and emotional support for physical activity were significantly associated with the child's physical activity. Results indicate that the association of various types of social support with children's physical activity and eating behaviors differ across racial/ethnic groups.
These results provide considerations for future interventions that aim to enhance parental support to improve children's energy balance-related behaviors.
Summary Background Alleles of the apolipoprotein E (APOE) gene modulate risk for Alzheimer's disease, with carriers of the ε4 allele being at increased risk and carriers of the ε2 allele possibly at ...decreased risk compared with non-carriers. Our aim was to determine whether possession of an ε4 allele would confer children with a neural substrate that might render them at risk for Alzheimer's disease, and whether carriers of the ε2 allele might have a so-called protective cortical morphology. Methods 239 healthy children and adolescents were genotyped and had repeated neuroanatomic MRI (total 530 scans). Mixed model regression was used to determine whether the developmental trajectory of the cortex differed by genotype. Findings Cortical thickness of the left entorhinal region was significantly thinner in ε4 carriers than it was in non-ε4 carriers (3·79 SE 0·06 mm, range 1·54–5·24 vs 3·94 0·03 mm, 2·37–6·11; p=0·03). There was a significant stepwise increase in cortical thickness in the left entorhinal regions, with ε4 carriers having the thinnest cortex and ε2 carriers the thickest, with ε3 homozygotes occupying an intermediate position (left β 0·11 SE 0·05, p=0·02). Neuroanatomic effects seemed fixed and non-progressive, with no evidence of accelerated cortical loss in young healthy ε4 carriers. Interpretation Alleles of the apolipoprotein E gene have distinct neuroanatomic signatures, identifiable in childhood. The thinner entorhinal cortex in individuals with the ε4 allele might contribute to risk of Alzheimer's disease.
Structural maturation of fiber tracts in the human brain, including an increase in the diameter and myelination of axons, may play a role in cognitive development during childhood and adolescence. A ...computational analysis of structural magnetic resonance images obtained in 111 children and adolescents revealed age-related increases in white matter density in fiber tracts constituting putative corticospinal and frontotemporal pathways. The maturation of the corticospinal tract was bilateral, whereas that of the frontotemporal pathway was found predominantly in the left (speech-dominant) hemisphere. These findings provide evidence for a gradual maturation, during late childhood and adolescence, of fiber pathways presumably supporting motor and speech functions.
Various anatomic brain abnormalities have been reported for attention-deficit/hyperactivity disorder (ADHD), with varying methods, small samples, cross-sectional designs, and without accounting for ...stimulant drug exposure.
To compare regional brain volumes at initial scan and their change over time in medicated and previously unmedicated male and female patients with ADHD and healthy controls.
Case-control study conducted from 1991-2001 at the National Institute of Mental Health, Bethesda, Md, of 152 children and adolescents with ADHD (age range, 5-18 years) and 139 age- and sex-matched controls (age range, 4.5-19 years) recruited from the local community, who contributed 544 anatomic magnetic resonance images.
Using completely automated methods, initial volumes and prospective age-related changes of total cerebrum, cerebellum, gray and white matter for the 4 major lobes, and caudate nucleus of the brain were compared in patients and controls.
On initial scan, patients with ADHD had significantly smaller brain volumes in all regions, even after adjustment for significant covariates. This global difference was reflected in smaller total cerebral volumes (-3.2%, adjusted F(1,280) = 8.30, P =.004) and in significantly smaller cerebellar volumes (-3.5%, adjusted F(1,280) = 12.29, P =.001). Compared with controls, previously unmedicated children with ADHD demonstrated significantly smaller total cerebral volumes (overall F(2,288) = 6.65; all pairwise comparisons Bonferroni corrected, -5.8%; P =.002) and cerebellar volumes (-6.2%, F( 2,288) = 8.97, P<.001). Unmedicated children with ADHD also exhibited strikingly smaller total white matter volumes (F(2,288) = 11.65) compared with controls (-10.7%, P<.001) and with medicated children with ADHD (-8.9%, P<.001). Volumetric abnormalities persisted with age in total and regional cerebral measures (P =.002) and in the cerebellum (P =.003). Caudate nucleus volumes were initially abnormal for patients with ADHD (P =.05), but diagnostic differences disappeared as caudate volumes decreased for patients and controls during adolescence. Results were comparable for male and female patients on all measures. Frontal and temporal gray matter, caudate, and cerebellar volumes correlated significantly with parent- and clinician-rated severity measures within the ADHD sample (Pearson coefficients between -0.16 and -0.26; all P values were <.05).
Developmental trajectories for all structures, except caudate, remain roughly parallel for patients and controls during childhood and adolescence, suggesting that genetic and/or early environmental influences on brain development in ADHD are fixed, nonprogressive, and unrelated to stimulant treatment.
Pediatric neuroimaging studies, up to now exclusively cross sectional, identify linear decreases in cortical gray matter and increases in white matter across ages 4 to 20. In this large-scale ...longitudinal pediatric neuroimaging study, we confirmed linear increases in white matter, but demonstrated nonlinear changes in cortical gray matter, with a preadolescent increase followed by a postadolescent decrease. These changes in cortical gray matter were regionally specific, with developmental curves for the frontal and parietal lobe peaking at about age 12 and for the temporal lobe at about age 16, whereas cortical gray matter continued to increase in the occipital lobe through age 20.
Abstract Objective To examine if gardening experience and enjoyment are associated with vegetable exposure, preferences, and consumption of vegetables among low-income third-grade children. Design ...Cross-sectional study design, using baseline data from the Texas! Grow! Eat! Go! study. Setting Twenty-eight Title I elementary schools located in different counties in Texas. Participants Third-grade students (n = 1,326, 42% Hispanic) Main Outcome Measures Gardening experience, gardening enjoyment, vegetable exposure, preference, and consumption. Analysis Random-effects regression models, adjusted for age, sex, ethnicity, and body mass index percentile of child, estimated means and standard errors of vegetable consumption, exposure, and preference by levels of gardening experience and enjoyment. Wald χ2 tests evaluated the significance of differences in means of outcomes across levels of gardening experience and enjoyment. Results Children with more gardening experience had greater vegetable exposure and higher vegetable preference and consumed more vegetables compared with children who reported less gardening experience. Those who reported that they enjoyed gardening had the highest levels of vegetable exposure, preference, and consumption. Conclusions and Implications Garden-based interventions can have an important and positive effect on children's vegetable consumption by increasing exposure to fun gardening experiences.
We present a unified statistical approach to deformation-based morphometry applied to the cortical surface. The cerebral cortex has the topology of a 2D highly convoluted sheet. As the brain develops ...over time, the cortical surface area, thickness, curvature, and total gray matter volume change. It is highly likely that such age-related surface changes are not uniform. By measuring how such surface metrics change over time, the regions of the most rapid structural changes can be localized. We avoided using surface flattening, which distorts the inherent geometry of the cortex in our analysis and it is only used in visualization. To increase the signal to noise ratio, diffusion smoothing, which generalizes Gaussian kernel smoothing to an arbitrary curved cortical surface, has been developed and applied to surface data. Afterward, statistical inference on the cortical surface will be performed via random fields theory. As an illustration, we demonstrate how this new surface-based morphometry can be applied in localizing the cortical regions of the gray matter tissue growth and loss in the brain images longitudinally collected in the group of children and adolescents.
PDF
