Neuroanatomical consequences of very preterm birth in middle childhood

Language performance and brain volumes, asymmetry, and cortical thickness in children born extremely preterm

BACKGROUND

Children born preterm are more prone to have language difficulties. Few studies focus on children born extremely preterm (EPT) and the structural differences in language-related regions between these children and children born at term.

METHODS

Our study used T1-weighted magnetic resonance imaging (MRI) scans to calculate the brain volumetry, brain asymmetry, and cortical thickness of language-related regions in 50 children born EPT and 37 term-born controls at 10 years of age. The language abilities of 41 of the children born EPT and 29 term-born controls were then assessed at 12 years of age, using the Wechsler Intelligence Scale for Children, Fifth Edition and the Clinical Evaluations of Language Fundamentals, Fourth Edition. The differences between MRI parameters and their associations with language outcomes were compared in the two groups.

RESULTS

Brain volume and cortical thickness of language-related regions were reduced in children born EPT, but volumetric asymmetry was not different between children born EPT and at term. In children born EPT the brain volume was related to language outcomes, prior to adjustments for full-scale IQ.

CONCLUSIONS

These findings expand our understanding of the structural correlates underlying impaired language performance in children born with EPT.

IMPACT

The article expands understanding of the structure-function relationship between magnetic resonance imaging measurements of language-related regions and language outcomes for children born extremely preterm beyond infancy. Most literature to date has focused on very preterm children, but the focus in this paper is on extreme prematurity and language outcomes. While the brain volume and cortical thickness of language-related regions were reduced in children born EPT only the volume, prior to adjustment for full-scale IQ, was associated with language outcomes. We found no differences in volumetric asymmetry between children born EPT and at term.

Extreme prematurity and perinatal risk factors related to extremely preterm birth are associated with complex patterns of regional brain volume alterations at 10 years of age: a voxel-based morphometry study

Objective

Structural brain volumetric differences have been investigated previously in very preterm children. However, children born extremely preterm, at the border of viability, have been studied to a lesser degree. Our group previously analyzed children born extremely preterm at term using voxel-based morphometry. In this study, we aimed to examine regional gray and white matter differences for children born extremely preterm derived from the same cohort during childhood. We also aimed to explore the effect of perinatal risk factors on brain volumes in the same group.

Methods

At 10 years of age, 51 children born extremely preterm (before 27 weeks and 0 days) and 38 term-born controls with high-quality 3.0 Tesla magnetic resonance images were included. Statistical analyses using voxel-based morphometry were conducted on images that were normalized using age-specific templates, modulated, and smoothed. Analyses were also performed in stratified groups of children born extremely preterm in the absence or presence of perinatal risk factors that have previously been shown to be associated with volumetric differences at term.

Results

We found volumetric decreases in gray and white matter in the temporal lobes, gray matter decreases in the precuneus gyri, and white matter decreases in the anterior cingulum for children born extremely preterm (all p < 0.001, and p_fwe < 0.05). Gray and white matter increases were predominantly observed in the right posterior cingulum and occipital lobe (all p < 0.001, and p_fwe < 0.05). Of the examined perinatal risk factors, intraventricular hemorrhage grades I-II compared with no intraventricular hemorrhage and patent ductus arteriosus ligation compared with no treated patent ductus arteriosus or patent ductus arteriosus treated with ibuprofen led to volumetric differences at 10 years of age (all p < 0.001, and p_fwe < 0.05).

Conclusions

Children born extremely preterm exhibit volumetric alterations in a pattern overlapping that previously found at term, where many regions with differences are the main hubs of higher order networks. Some, but not all, risk factors known to be associated with structural alterations at term were associated with alterations at 10 years of age.

Longitudinal Structural and Diffusion-Weighted Neuroimaging of Young Children Born Preterm

BACKGROUND

Children born preterm are at risk for diffuse injury to subcortical gray and white matter.

METHODS

We used a longitudinal cohort study to examine the development of subcortical gray matter and white matter volumes, and diffusivity measures of white matter tracts following preterm birth. Our participants were 47 children born preterm (24 to 32 weeks gestational age) and 28 children born at term. None of the children born preterm had significant neonatal brain injury. Children received structural and diffusion weighted magnetic resonance imaging scans at ages five, six, and seven years. We examined volumes of amygdala, hippocampus, caudate nucleus, putamen, thalamus, brainstem, cerebellar white matter, intracranial space, and ventricles, and volumes, fractional anisotropy, and mean diffusivity of anterior thalamic radiation, cingulum, corticospinal tract, corpus callosum, inferior frontal occipital fasciculus, inferior longitudinal fasciculus, temporal and parietal superior longitudinal fasciculus, and uncinate fasciculus.

RESULTS

Children born preterm had smaller volumes of thalamus, brainstem, cerebellar white matter, cingulum, corticospinal tract, inferior frontal occipital fasciculus, uncinate fasciculus, and temporal superior longitudinal fasciculus, whereas their ventricles were larger compared with term-born controls. We found no significant effect of preterm birth on diffusivity measures. Despite developmental changes and growth, group differences were present and similarly strong at all three ages.

CONCLUSION

Even in the absence of significant neonatal brain injury, preterm birth has a persistent impact on early brain development. The lack of a significant term status by age interaction suggests a delayed developmental trajectory.

Amygdala subnuclei volumes, functional connectivity, and social–emotional outcomes in children born very preterm

Children born very preterm can demonstrate social-cognitive impairments, which may result from limbic system dysfunction. Altered development of the subnuclei of the amygdala, stress-sensitive regions involved in emotional processing, may be key predictors of social-skill development. In a prospective cohort study, 7-year-old children born very preterm underwent neurodevelopmental testing and brain MRI. The Child Behavioral Checklist was used to assess social–emotional outcomes. Subnuclei volumes were extracted automatically from structural scans (n = 69) and functional connectivity (n = 66) was examined. General Linear Models were employed to examine the relationships between amygdala subnuclei volumes and functional connectivity values and social–emotional outcomes. Sex was a significant predictor of all social–emotional outcomes (P < 0.05), with boys having poorer social–emotional outcomes. Smaller right basal nuclei volumes (B = -0.043, P = 0.014), smaller right cortical volumes (B = -0.242, P = 0.02) and larger right central nuclei volumes (B = 0.85, P = 0.049) were associated with increased social problems. Decreased connectivity strength between thalamic and amygdala networks and smaller right basal volumes were significant predictors of greater social problems (both, P < 0.05), effects which were stronger in girls (P = 0.025). Dysregulated maturation of the amygdala subnuclei, along with altered connectivity strength in stress-sensitive regions, may reflect stress-induced dysfunction and can be predictive of social–emotional outcomes.

Development of the mentalizing network structures and theory of mind in extremely preterm youth

Adolescents born preterm (<37 weeks of gestation) are at elevated risk for deficits in social cognition and peer relationships. Theory of Mind (ToM) is a complex form of social cognition important for regulating social interactions. ToM and the underlying mentalizing network continue to develop across adolescence. The present study recruited 48 adolescents (12-17 years old) who were either born extremely preterm (EPT; <28 weeks of gestation) or full-term (FT) at birth. Cortical thickness, gray matter volume and surface area were measured in four regions of the mentalizing network: the temporoparietal junction, anterior temporal cortex, posterior superior temporal sulcus and frontal pole (mBA10). We also assessed the adolescents' performance on a ToM task. Findings revealed both group differences and group-by-age interaction effects in the gray matter indices within the temporal lobe regions of the mentalizing network. The EPT group also performed significantly worse than the FT group on the ToM task. The cortical structural measures that discriminated the EPT and FT groups were not related to ToM performance. These results highlight altered developmental changes in brain regions underlying mentalizing functions in EPT adolescents relative to FT controls.

Preterm birth alters the development of cortical microstructure and morphology at term-equivalent age

INTRODUCTION

The dynamic nature and complexity of the cellular events that take place during the last trimester of pregnancy make the developing cortex particularly vulnerable to perturbations. Abrupt interruption to normal gestation can lead to significant deviations to many of these processes, resulting in atypical trajectory of cortical maturation in preterm birth survivors.

METHODS

We sought to first map typical cortical micro- and macrostructure development using invivo MRI in a large sample of healthy term-born infants scanned after birth (n = 259). Then we offer a comprehensive characterization of the cortical consequences of preterm birth in 76 preterm infants scanned at term-equivalent age (37-44 weeks postmenstrual age). We describe the group-average atypicality, the heterogeneity across individual preterm infants, and relate individual deviations from normative development to age at birth and neurodevelopment at 18 months.

RESULTS

In the term-born neonatal brain, we observed heterogeneous and regionally specific associations between age at scan and measures of cortical morphology and microstructure, including rapid surface expansion, greater cortical thickness, lower cortical anisotropy and higher neurite orientation dispersion. By term-equivalent age, preterm infants had on average increased cortical tissue water content and reduced neurite density index in the posterior parts of the cortex, and greater cortical thickness anteriorly compared to term-born infants. While individual preterm infants were more likely to show extreme deviations (over 3.1 standard deviations) from normative cortical maturation compared to term-born infants, these extreme deviations were highly variable and showed very little spatial overlap between individuals. Measures of regional cortical development were associated with age at birth, but not with neurodevelopment at 18 months.

CONCLUSION

We showed that preterm birth alters cortical micro- and macrostructural maturation near the time of full-term birth. Deviations from normative development were highly variable between individual preterm infants.

Event-related potentials evoked by skin puncture reflect activation of Aβ fibers: comparison with intraepidermal and transcutaneous electrical stimulations

Background

Recently, event-related potentials (ERPs) evoked by skin puncture, commonly used for blood sampling, have received attention as a pain assessment tool in neonates. However, their latency appears to be far shorter than the latency of ERPs evoked by intraepidermal electrical stimulation (IES), which selectively activates nociceptive Aδ and C fibers. To clarify this important issue, we examined whether ERPs evoked by skin puncture appropriately reflect central nociceptive processing, as is the case with IES.

Methods

In Experiment 1, we recorded evoked potentials to the click sound produced by a lance device (click-only), lance stimulation with the click sound (click+lance), or lance stimulation with white noise (WN+lance) in eight healthy adults to investigate the effect of the click sound on the ERP evoked by skin puncture. In Experiment 2, we tested 18 heathy adults and recorded evoked potentials to shallow lance stimulation (SL) with a blade that did not reach the dermis (0.1 mm insertion depth); normal lance stimulation (CL) (1 mm depth); transcutaneous electrical stimulation (ES), which mainly activates Aβ fibers; and IES, which selectively activates Aδ fibers when low stimulation current intensities are applied. White noise was continuously presented during the experiments. The stimulations were applied to the hand dorsum. In the SL, the lance device did not touch the skin and the blade was inserted to a depth of 0.1 mm into the epidermis, where the free nerve endings of Aδ fibers are located, which minimized the tactile sensation caused by the device touching the skin and the activation of Aβ fibers by the blade reaching the dermis. In the CL, as in clinical use, the lance device touched the skin and the blade reached a depth of 1 mm from the skin surface, i.e., the depth of the dermis at which the Aβ fibers are located.

Results

The ERP N2 latencies for click-only (122 ± 2.9 ms) and click+lance (121 ± 6.5 ms) were significantly shorter than that for WN+lance (154 ± 7.1 ms). The ERP P2 latency for click-only (191 ± 11.3 ms) was significantly shorter than those for click+lance (249 ± 18.6 ms) and WN+lance (253 ± 11.2 ms). This suggests that the click sound shortens the N2 latency of the ERP evoked by skin puncture. The ERP N2 latencies for SL, CL, ES, and IES were 146 ± 8.3, 149 ± 9.9, 148 ± 13.1, and 197 ± 21.2 ms, respectively. The ERP P2 latencies were 250 ± 18.2, 251 ± 14.1, 237 ± 26.3, and 294 ± 30.0 ms, respectively. The ERP latency for SL was significantly shorter than that for IES and was similar to that for ES. This suggests that the penetration force generated by the blade of the lance device activates the Aβ fibers, consequently shortening the ERP latency.

Conclusions

Lance ERP may reflect the activation of Aβ fibers rather than Aδ fibers. A pain index that correctly and reliably reflects nociceptive processing must be developed to improve pain assessment and management in neonates.

Psychosocial and Neurobiological Vulnerabilities of the Hospitalized Preterm Infant and Relevant Non-pharmacological Pain Mitigation Strategies

Background: Preterm pain is common in the Neonatal Intensive Care Unit (NICU), with multiple invasive procedures occurring daily. Objective: To review the psychosocial and neurobiological vulnerabilities of preterm infants and to provide an updated overview of non-pharmacological strategies for acute procedural pain in hospitalized preterm infants. Methods: We utilized a narrative review methodology, which also included a synthesis of key pieces of published systematic reviews that are relevant to the current work. Results and Conclusions: Preterm infants are uniquely susceptible to the impact of painful procedures and prolonged separation from caregivers that are often inherent in a NICU stay. Non-pharmacological interventions can be efficacious for mitigating procedural pain for preterm infants. Interventions should continue to be evaluated with high quality randomized controlled trials, and should endeavor to take into account the neurobiological and psychosocial aspects of preterm vulnerability for pain prevention and management strategies.

Neurodevelopmental impairment is associated with altered white matter development in a cohort of school-aged children born very preterm

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Over 30% of children born VPT have neurodevelopmental impairment.

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VPT children with neurodevelopmental impairment have smaller total brain volume.

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VPT children with neurodevelopmental impairment have lower FA and higher RD.

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Neurodevelopmental impairment in a VPT cohort may reflect altered microstructure.

Individuals born very preterm (<32 weeks gestation) have altered brain growth and white matter maturation relative to their full-term peers, and approximately 30% will experience neurodevelopmental impairment. We investigated the relationship between neurodevelopmental impairment and MRI measures of white matter microstructure and brain volume.

Children born before 30 weeks’ gestation or who had very low birthweight (< 1500 g) underwent neurodevelopmental assessment and MRI at age 7 years as part of the PIANO study, a New Zealand-based cohort study. Fractional anisotropy (FA) and diffusivity measures were derived from diffusion tensor imaging to index white matter microstructure. Volumes were derived from T1-weighted imaging. Neurodevelopmental impairment was defined as a score < 85 on the Wechsler Intelligence Scale for Children, <5th centile on the Movement Assessment Battery for Children or a diagnosis of cerebral palsy by a paediatrician. Relationships between MRI and neurodevelopmental impairment were assessed with general linear models adjusted for sex, gestational age at birth, birthweight z-score, age at assessment, New Zealand Deprivation index score and multiplicity.

Children with neurodevelopmental impairment (n = 38) had smaller total brain, cortical grey matter and cerebral white matter volumes compared to children without neurodevelopmental impairment (n = 62) (p < 0.05, false discovery rate corrected), but the regional volume differences did not remain significant after adjustment for total brain volume. Lower FA and higher radial diffusivity were observed in the superior longitudinal fasciculi, uncinate fasciculi and right hemisphere corticospinal tract in children with neurodevelopmental impairment. This may reflect differences in cellular properties such as myelination or axonal packing. Neurodevelopmental impairment may reflect smaller overall brain volume and altered microstructure in white matter tracts that are important for language, cognitive and motor functioning.

Breakdown of Whole-brain Dynamics in Preterm-born Children

The brain operates at a critical point that is balanced between order and disorder. Even during rest, unstable periods of random behavior are interspersed with stable periods of balanced activity patterns that support optimal information processing. Being born preterm may cause deviations from this normal pattern of development. We compared 33 extremely preterm (EPT) children born at < 27 weeks of gestation and 28 full-term controls. Two approaches were adopted in both groups, when they were 10 years of age, using structural and functional brain magnetic resonance imaging data. The first was using a novel intrinsic ignition analysis to study the ability of the areas of the brain to propagate neural activity. The second was a whole-brain Hopf model, to define the level of stability, desynchronization, or criticality of the brain. EPT-born children exhibited fewer intrinsic ignition events than controls; nodes were related to less sophisticated aspects of cognitive control, and there was a different hierarchy pattern in the propagation of information and suboptimal synchronicity and criticality. The largest differences were found in brain nodes belonging to the rich-club architecture. These results provide important insights into the neural substrates underlying brain reorganization and neurodevelopmental impairments related to prematurity.

Early protein intake predicts functional connectivity and neurocognition in preterm born children

Nutritional intake can promote early neonatal brain development in very preterm born neonates (< 32 weeks’ gestation). In a group of 7-year-old very preterm born children followed since birth, we examined whether early nutrient intake in the first weeks of life would be associated with long-term brain function and neurocognitive skills at school age. Children underwent resting-state functional MRI (fMRI), intelligence testing (Wechsler Intelligence Scale for Children, 5th Ed) and visual-motor processing (Beery-Buktenica, 5th Ed) at 7 years. Relationships were assessed between neonatal macronutrient intakes, functional connectivity strength between thalamic and default mode networks (DMN), and neuro-cognitive function using multivariable regression. Greater functional connectivity strength between thalamic networks and DMN was associated with greater intake of protein in the first week (β = 0.17; 95% CI 0.11, 0.23, p < 0.001) but lower intakes of fat (β = − 0.06; 95% CI − 0.09, − 0.02, p = 0.001) and carbohydrates (β = − 0.03; 95% CI − 0.04, − 0.01, p = 0.003). Connectivity strength was also associated with protein intake during the first month (β = 0.22; 95% CI 0.06, 0.37, p = 0.006). Importantly, greater thalamic-DMN connectivity strength was associated with higher processing speed indices (β = 26.9; 95% CI 4.21, 49.49, p = 0.02) and visual processing scores (β = 9.03; 95% CI 2.27, 15.79, p = 0.009). Optimizing early protein intake may contribute to promoting long-term brain health in preterm-born children.

Can Event-Related Potentials Evoked by Heel Lance Assess Pain Processing in Neonates? A Systematic Review

To clarify the possibility of event-related potential (ERP) evoked by heel lance in neonates as an index of pain assessment, knowledge acquired by and problems of the methods used in studies on ERP evoked by heel lance in neonates were systematically reviewed, including knowledge about Aδ and C fibers responding to noxious stimuli and Aβ fibers responding to non-noxious stimuli. Of the 863 reports searched, 19 were selected for the final analysis. The following points were identified as problems for ERP evoked by heel lance in neonates to serve as a pain assessment index: (1) It is possible that the ERP evoked by heel lance reflected the activation of Aβ fibers responding to non-noxious stimuli and not the activation of Aδ or C fibers responding to noxious stimulation; (2) Sample size calculation was presented in few studies, and the number of stimulation trials to obtain an averaged ERP was small. Accordingly, to establish ERP evoked by heel lance as a pain assessment in neonates, it is necessary to perform a study to clarify ERP evoked by Aδ- and C-fiber stimulations accompanied by heel lance in neonates.

The effects of the functional interplay between the Default Mode and Executive Control Resting State Networks on cognitive outcome in preterm born infants at 6 months of age

Preterm birth can affect cognitive functions, such as attention or more generally executive control mechanisms, with severity in impairments proportional to prematurity. The functional cross-talk between the Default Mode (DMN) and Executive Control (ECN) networks mirrors the integrity of cognitive processing and is directly related to brain development. In this study, a cohort of 20 preterm-born infants was investigated using rs-fMRI. First, we addressed biological maturity of the DMN per se and its interplay with the ECN in terms of patterns of increased functional connectivity. Second, we assessed the impact of the degree of prematurity on the DMN-ECN functional interplay development in relation to cognitive outcome at six months. Our results highlighted the emergence of DMN in preterm neonates, with connectivity strength and synchronization between the anterior DMN hub and frontal areas increasing as a function of biological maturity. Further, cognitive scores at 6 months were predicted by mPFC-ECN connectivity strength with degree of prematurity impacting on mPFC-ECN connectivity and triggering differential patterns of functional maturation of the ECN for very early/early and moderate/late preterm neonates. Our findings suggest that the prematurity window allows to observe precursors of functional plasticity that may underlie different developmental trajectories in preterm children.

Association of Gestational Age at Birth With Brain Morphometry

IMPORTANCE

Preterm and postterm births are associated with adverse neuropsychiatric outcomes. However, it remains unclear whether variation of gestational age within the 37- to 42-week range of term deliveries is associated with neurodevelopment.

OBJECTIVE

To investigate the association of gestational age at birth (GAB) with structural brain morphometry in children aged 10 years.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study included pregnant women living in Rotterdam, the Netherlands, with an expected delivery date between April 1, 2002, and January 31, 2006. The study evaluated 3079 singleton children with GAB ranging from 26.3 to 43.3 weeks and structural neuroimaging at 10 years of age from the Generation R Study, a longitudinal, population-based prospective birth cohort from early pregnancy onward in Rotterdam. Data analysis was performed from March 1, 2019, to February 28, 2020, and at the time of the revision based on reviewer suggestions.

EXPOSURES

The GAB was calculated based on ultrasonographic assessment of crown-rump length (<12 weeks 5 days) or biparietal diameter (≥12 weeks 5 days) in dedicated research centers.

MAIN OUTCOMES AND MEASURES

Brain structure, including global and regional brain volumes and surface-based cortical measures (thickness, surface area, and gyrification), was quantified by magnetic resonance imaging.

RESULTS

In the 3079 children (1546 [50.2%] female) evaluated at 10 years of age, GAB was linearly associated with global and regional brain volumes. Longer gestational duration was associated with larger brain volumes; for example, every 1-week-longer gestational duration corresponded to an additional 4.5 cm3/wk (95% CI, 2.7-6.3 cm3/wk) larger total brain volume. These associations persisted when the sample was restricted to children born at term (GAB of 37-42 weeks: 4.8 cm3/wk; 95% CI, 1.8-7.7 cm3/wk). No evidence of nonlinear associations between GA and brain morphometry was observed.

CONCLUSIONS AND RELEVANCE

In this cohort study, gestational duration was linearly associated with brain morphometry during childhood, including within the window of term delivery. These findings may have marked clinical importance, particularly given the prevalence of elective cesarean deliveries.

The degree of prematurity affects functional brain activity in preterm born children at school-age: An EEG study

Prematurely born children are at higher risk for long-term adverse motor and cognitive outcomes. The aim of this paper was to compare quantitative measures derived from electroencephalography (EEG) between extremely (EP) and very prematurely (VP) born children at 9-10 years of age. Fifty-five children born <32 weeks' of gestation underwent EEG at 9-10 years of age and were assessed for motor development and cognitive outcome. Relative frequency power and functional connectivity, as measured by the Phase Lag Index (PLI), were calculated for all frequency bands. Per subject, power spectrum and functional connectivity results were averaged over all channels and pairwise PLI values to explore differences in global frequency power and functional connectivity between EP and VP children. Brain networks were constructed for the upper alpha frequency band using the Minimum Spanning Tree method and were compared between EP and VP children. In addition, the relationships between upper alpha quantitative EEG results and cognitive and motor outcomes were investigated. Relative power and functional connectivity were significantly higher in VP than EP children in the upper alpha frequency band, and VP children had more integrated networks. A strong positive correlation was found between relative upper alpha power and motor outcome whilst controlling for gestational age, age during EEG recording, and gender (ρ = 0.493, p = 0.004). These results suggest that 9-10 years after birth, the effects of the degree of prematurity can be observed in terms of alterations in functional brain activity and that motor deficits are associated with decreases in relative upper alpha power.

Emerging atypical connectivity networks for processing angry and fearful faces in very preterm born children

Very preterm born (VPT) children are those born before 32/40 weeks' gestational age and comprise 10% of the 15 million babies born prematurely worldwide each year. Due to advancements in neonatal medicine, the survival rate of VPT birth has increased, but few studies have investigated the nonmedical, social-cognitive morbidities that affect these children. In this study, we examined emotional face processing networks in VPT compared to age and sex matched full-term born (FT) children. Magnetoencephalography (MEG) was used to test VPT and FT born children at 6 years (n = 78) and 8 years (n = 83). Children were assessed using an implicit emotion face-processing task. Happy, fearful, and angry faces were presented for 150 ms, but children were asked to respond by button press to the location of a control pixelated image of the face displayed on the side of the screen opposite to the face. Children rated the valence of the images on a five-point scale. Group differences showed that VPT children rated angry faces more positively than their FT peers. VPT children had reduced connectivity for angry and fearful faces at 8 years in networks including regions such as the bilateral amygdala, superior temporal sulci, and anterior cingulate gyrus. Interventions should target both emotion recognition, as well as higher cognitive processes related to emotional control and thinking about one's own emotions.

Decreased cortical thickness mediates the relationship between premature birth and cognitive performance in adulthood

Cortical thickness (CTh) reflects cortical properties such as dendritic complexity and synaptic density, which are not only vulnerable to developmental disturbances caused by premature birth but also highly relevant for cognitive performance. We tested the hypotheses whether CTh in young adults is altered after premature birth and whether these aberrations are relevant for general cognitive abilities. We investigated CTh based on brain structural magnetic resonance imaging and surface-based morphometry in a large and prospectively collected cohort of 101 very premature-born adults (<32 weeks of gestation and/or birth weight [BW] below 1,500 g) and 111 full-term controls at 26 years of age. Cognitive performance was assessed by full-scale intelligence quotient (IQ) using the Wechsler Adult Intelligence Scale. CTh was reduced in frontal, parietal, and temporal associative cortices predominantly in the left hemisphere in premature-born adults compared to controls. We found a significant positive association of CTh with both gestational age and BW, particularly in the left hemisphere, and a significant negative association between CTh and intensity of neonatal treatment within limited regions bilaterally. Full-scale IQ and CTh in the left hemisphere were positively correlated. Furthermore, CTh in the left hemisphere acted as a mediator on the association between premature birth and full-scale IQ. Results provide evidence that premature born adults have widespread reduced CTh that is relevant for their general cognitive performance. Data suggest lasting reductions in cortical microstructure subserving CTh after premature birth.

Atypical neuromagnetic resting activity associated with thalamic volume and cognitive outcome in very preterm children

Children born very preterm, even in the absence of overt brain injury or major impairment, are at increased risk of cognitive difficulties. This risk is associated with developmental disruptions of the thalamocortical system during critical periods while in the neonatal intensive care unit. The thalamus is an important structure that not only relays sensory information but acts as a hub for integration of cortical activity which regulates cortical power across a range of frequencies. In this study, we investigate the association between atypical power at rest in children born very preterm at school age using magnetoencephalography (MEG), neurocognitive function and structural alterations related to the thalamus using MRI. Our results indicate that children born extremely preterm have higher power at slow frequencies (delta and theta) and lower power at faster frequencies (alpha and beta), compared to controls born full-term. A similar pattern of spectral power was found to be associated with poorer neurocognitive outcomes, as well as with normalized T1 intensity and the volume of the thalamus. Overall, this study provides evidence regarding relations between structural alterations related to very preterm birth, atypical oscillatory power at rest and neurocognitive difficulties at school-age children born very preterm.

Environmental Influences on Infant Cortical Thickness and Surface Area

Cortical thickness (CT) and surface area (SA) vary widely between individuals and are associated with intellectual ability and risk for various psychiatric and neurodevelopmental conditions. Factors influencing this variability remain poorly understood, but the radial unit hypothesis, as well as the more recent supragranular cortex expansion hypothesis, suggests that prenatal and perinatal influences may be particularly important. In this report, we examine the impact of 17 major demographic and obstetric history variables on interindividual variation in CT and SA in a unique sample of 805 neonates who received MRI scans of the brain around 2 weeks of age. Birth weight, postnatal age at MRI, gestational age at birth, and sex emerged as important predictors of SA. Postnatal age at MRI, paternal education, and maternal ethnicity emerged as important predictors of CT. These findings suggest that individual variation in infant CT and SA is explained by different sets of environmental factors with neonatal SA more strongly influenced by sex and obstetric history and CT more strongly influenced by socioeconomic and ethnic disparities. Findings raise the possibility that interventions aimed at reducing disparities and improving obstetric outcomes may alter prenatal/perinatal cortical development.

Tracking regional brain growth up to age 13 in children born term and very preterm

Serial regional brain growth from the newborn period to adolescence has not been described. Here, we measured regional brain growth in 216 very preterm (VP) and 45 full-term (FT) children. Brain MRI was performed at term-equivalent age, 7 and 13 years in 82 regions. Brain volumes increased between term-equivalent and 7 years, with faster growth in the FT than VP group. Perinatal brain abnormality was associated with less increase in brain volume between term-equivalent and 7 years in the VP group. Between 7 and 13 years, volumes were relatively stable, with some subcortical and cortical regions increasing while others reduced. Notably, VP infants continued to lag, with overall brain size generally less than that of FT peers at 13 years. Parieto–frontal growth, mainly between 7 and 13 years in FT children, was associated with higher intelligence at 13 years. This study improves understanding of typical and atypical regional brain growth.

In this longitudinal study, the authors tracked the course of brain development from birth to adolescence (age 13 years) and examined the effects of very preterm birth. Very preterm children showed slower brain growth from age 0 (term equivalent) to age 7.

Variations in brain morphometry among healthy preschoolers born preterm

BACKGROUND

Preterm birth is associated with an increased risk of neonatal brain injury, which can lead to alterations in brain maturation. Despite being born without the most significant medical consequences of preterm birth, infants born early remain at increased risk for subtle brain injury that affects future neurodevelopment and functioning.

AIMS

To investigate the gray matter morphometry measures of cortical thickness, cortical surface area, and sulcal depth using MRI at 5 years of age in healthy children born preterm.

STUDY DESIGN

Cohort study.

SUBJECTS

Participants were 52 children born preterm (<33 weeks gestational age) and 37 children born full term.

OUTCOME MEASURES

Cortical segmentation and calculation of morphometry measures were completed using FreeSurfer version 5.3.0 and compared between groups using surface-based, voxel-wise analyses.

RESULTS

The preterm group had a significantly thinner cortex in temporal and parietal regions while cortical thickness was significantly larger within occipital and inferior frontal regions. Surface area was significantly reduced within the fusiform gyrus. Sulcal depth was significantly lower within the posterior parietal and inferior temporal regions but greater in the middle temporal and medial parietal regions.

CONCLUSIONS

Regional differences were found between preschoolers born preterm and full term in cortical thickness, surface area, and sulcal depth. Cortical thickness differences primarily overlapped with regions found in previous studies of older children and adults. Differences in sulcal depth may represent additional areas of maturational differences in preterm children. These findings likely represent a combination of delayed maturation and permanent alterations caused by the perinatal processes associated with preterm birth.

Mapping the neuroanatomical impact of very preterm birth across childhood

Those born very preterm (VPT; <32 weeks gestational age) have an increased risk in developing a wide range of cognitive deficits. In early-to-late childhood, brain structure has been shown to be altered in VPT compared to full-term (FT) children; however, the results are inconsistent. The current study examined subcortical volumes, cortical thickness, and surface area in a large cohort of VPT and FT children aged 4-12 years. Structural magnetic resonance imaging (MRI) was obtained on 120 VPT and 146 FT children who returned up to three times, resulting in 176 VPT and 173 FT unique data points. For each participant, Corticometric Iterative Vertex-based Estimation of Thickness was used to obtain global measurements of total brain, cortical grey and cortical white matter volumes, along with surface-based measurements of cortical thickness and surface area, and Multiple Automatically Generated Templates (MAGeT) brain segmentation tool was used to segment the subcortical structures. To examine group differences and group-age interactions, mixed-effects models were used (controlling for whole-brain volume). We found few differences between the two groups in subcortical volumes. The VPT children showed increased cortical thickness in frontal, occipital and fusiform gyri and inferior pre-post-central areas, while thinning occurred in the midcingulate. Cortical thickness in occipital regions showed more rapid decreases with age in the VPT compared to the FT children. VPT children also showed both regional increases, particularly in the temporal lobe, and decreases in surface area. Our results indicate a delayed maturational trajectory in those born VPT.

A machine learning investigation of volumetric and functional MRI abnormalities in adults born preterm

Imaging studies have characterized functional and structural brain abnormalities in adults after premature birth, but these investigations have mostly used univariate methods that do not account for hypothesized interdependencies between brain regions or quantify accuracy in identifying individuals. To overcome these limitations, we used multivariate machine learning to identify gray matter volume (GMV) and amplitude of low frequency fluctuations (ALFF) brain patterns that best classify young adults born very preterm/very low birth weight (VP/VLBW; n = 94) from those born full-term (FT; n = 92). We then compared the spatial maps of the structural and functional brain signatures and validated them by assessing associations with clinical birth history and basic cognitive variables. Premature birth could be predicted with a balanced accuracy of 80.7% using GMV and 77.4% using ALFF. GMV predictions were mediated by a pattern of subcortical and middle temporal reductions and volumetric increases of the lateral prefrontal, medial prefrontal, and superior temporal gyrus regions. ALFF predictions were characterized by a pattern including increases in the thalamus, pre- and post-central gyri, and parietal lobes, in addition to decreases in the superior temporal gyri bilaterally. Decision scores from each classification, assessing the degree to which an individual was classified as a VP/VLBW case, were predicted by the number of days in neonatal hospitalization and birth weight. ALFF decision scores also contributed to the prediction of general IQ, which highlighted their potential clinical significance. Combined, the results clarified previous research and suggested that primary subcortical and temporal damage may be accompanied by disrupted neurodevelopment of the cortex.

Altered myelin maturation in four year old children born very preterm

Children born very preterm (VPT; <32 weeks gestational age [GA]) are at greater risk for a range of cognitive deficits that typically manifest at school age. Here we examine the hypothesis that these children have altered myelin maturational that can be detected by myelin sensitive MRI measures prior to school age. We included 33 four-year old children born VPT (mean GA; 28.7 weeks) and 23 four-year old full term (FT) children and completed magnetization transfer (MT), T1-weighted (T1-w) and T2-weighted (T1-w) magnetic resonance imaging as well as developmental assessments. Both MT ratio (MTR) and T1-w/T2-w ratio images were calculated, and group differences were probed using tract-based spatial statistics (TBSS) in white matter, and region of interest (ROI) analysis in white, subcortical gray and cortical gray matter. The relations between MTR and T1-w/T2-w ratio, as well as with developmental assessments, were investigated in all three brain divisions. In children born VPT, TBSS and ROI analysis revealed that both MTR and T1-w/T2-w ratio were significantly reduced in white matter compared to children born FT. ROI analysis showed reductions in T1-w/T2-w ratio in VPT children compared to FT children in the thalamus, putamen and amygdala, as well as in the occipital and temporal lobes. Across the VPT and FT children, T1-w/T2-w ratio and MTR were highly correlated across white, subcortical gray and cortical gray matter. Both measures correlated positively with developmental assessments in individual white matter tracts and cortical and subcortical ROIs, suggesting that higher MTR and T1-w/T2-w ratio is related to better cognitive performance. Together these findings are consistent with delayed myelination in VPT born children.

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Very preterm children have widespread decreased MTR in white matter.

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T1-w/T2-w ratio measures showed consistent white matter alterations.

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T1-w/T2-w ratio was also reduced in subcortical, occipital and temporal regions.

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MTR and T1-w/T2-w were correlated throughout the brain.

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MTR and T1-w/T2-w correlated with developmental assessments.

Altered functional network connectivity relates to motor development in children born very preterm

Individuals born very preterm (<32 weeks gestation) are at increased risk for neuromotor impairments. The ability to characterize the structural and functional mechanisms underlying these impairments remains limited using existing neuroimaging techniques. Resting state-functional magnetic resonance imaging (rs-fMRI) holds promise for defining the functional network architecture of the developing brain in relation to typical and aberrant neurodevelopment. In 58 very preterm and 65 term-born children studied from birth to age 12 years, we examined relations between functional connectivity measures from low-motion rs-fMRI data and motor skills assessed using the Movement Assessment Battery for Children, 2nd edition. Across all subscales, motor performance was better in term than very preterm children. Examination of relations between functional connectivity and motor measures using enrichment analysis revealed between-group differences within cerebellar, frontoparietal, and default mode networks, and between basal ganglia-motor, thalamus-motor, basal ganglia-auditory, and dorsal attention-default mode networks. Specifically, very preterm children exhibited weaker associations between motor scores and thalamus-motor and basal ganglia-motor network connectivity. These findings highlight key functional brain systems underlying motor development. They also demonstrate persisting developmental effects of preterm birth on functional connectivity and motor performance in childhood, providing evidence for an alternative network architecture supporting motor function in preterm children.

Rapid Infant Prefrontal Cortex Development and Sensitivity to Early Environmental Experience

Over the last fifteen years, the emerging field of developmental cognitive neuroscience has described the relatively late development of prefrontal cortex in children and the relation between gradual structural changes and children's protracted development of prefrontal-dependent skills. Widespread recognition by the broader scientific community of the extended development of prefrontal cortex has led to the overwhelming perception of prefrontal cortex as a "late developing" region of the brain. However, despite its supposedly protracted development, multiple lines of research have converged to suggest that prefrontal cortex development may be particularly susceptible to individual differences in children's early environments. Recent studies demonstrate that the impacts of early adverse environments on prefrontal cortex are present very early in development: within the first year of life. This review provides a comprehensive overview of new neuroimaging evidence demonstrating that prefrontal cortex should be characterized as a "rapidly developing" region of the brain, discusses the converging impacts of early adversity on prefrontal circuits, and presents potential mechanisms via which adverse environments shape both concurrent and long-term measures of prefrontal cortex development. Given that environmentally-induced disparities are present in prefrontal cortex development within the first year of life, translational work in intervention and/or prevention science should focus on intervening early in development to take advantages of this early period of rapid prefrontal development and heightened plasticity.

Heritability estimates of cortical anatomy: The influence and reliability of different estimation strategies

Twin study designs have been previously used to investigate the heritability of neuroanatomical measures, such as regional cortical volumes. Volume can be fractionated into surface area and cortical thickness, where both measures are considered to have independent genetic and environmental bases. Region of interest (ROI) and vertex-wise approaches have been used to calculate heritability of cortical thickness and surface area in twin studies. In our study, we estimate heritability using the Human Connectome Project magnetic resonance imaging dataset composed of healthy young twin and non-twin siblings (mean age of 29, sample size of 757). Both ROI and vertex-wise methods were used to compare regional heritability of cortical thickness and surface area. Heritability estimates were controlled for age, sex, and total ipsilateral surface area or mean cortical thickness. In both approaches, heritability estimates of cortical thickness and surface area were lower when accounting for average ipsilateral cortical thickness and total surface area respectively. When comparing both approaches at a regional level, the vertex-wise approach showed higher surface area and lower cortical thickness heritability estimates compared to the ROI approach. The calcarine fissure had the highest surface area heritability estimate (ROI: 44%, vertex-wise: 50%) and posterior cingulate gyrus had the highest cortical thickness heritability (ROI: 50%, vertex-wise 40%). We also observed that limitations in image processing and variability in spatial averaging errors based on regional size may make obtaining true estimates of cortical thickness and surface area challenging in smaller regions. It is important to identify which approach is best suited to estimate heritability based on the research hypothesis and the size of the regions being investigated.

Cognitive outcomes in children and adolescents born very preterm: a meta-analysis

AIM

To estimate the association between very preterm birth (<32wks' gestation) and intelligence, executive functioning, and processing speed throughout childhood and adolescence, and to examine the effects of gestational age, birthweight, and age at assessment.

METHOD

Studies were included if children were born at earlier than 32 weeks' gestation, aged 4 to 17 years, had an age-matched term control group, and if the studies used standardized measures, were published in an English-language peer-reviewed journal, and placed no restrictions on participants based on task performance.

RESULTS

We evaluated 6163 children born very preterm and 5471 term-born controls from 60 studies. Children born very preterm scored 0.82 SDs (95% confidence interval [CI] 0.74-0.90; p<0.001) lower on intelligence tests, 0.51 SDs (95% CI 0.44-0.58; p<0.001) lower on measures of executive functioning, and 0.49 SDs (95% CI 0.39-0.60; p<0.001) lower on measures of processing speed than term-born controls. Gestational age and birthweight were associated with study effect size in intelligence and executive functioning of younger children only. Age at assessment was not associated with study effect size.

INTERPRETATION

Children born very preterm have medium to large deficits in these cognitive domains.

WHAT THIS PAPER ADDS

This meta-analysis is centred on very preterm birth and three cognitive domains. The three critical cognitive domains are intelligence, executive functioning, and processing speed.

Cortical morphometry and cognition in very preterm and term-born children at early school age

Very preterm birth influences brain development and may result in alterations of cortical morphometry. These structural alterations may interact with cognitive development. The aim of the present study was to investigate the structure-function relationship in school-aged very preterm and term-born control children. A comprehensive neuropsychological test battery was administered to 41 very preterm (<32 weeks of gestation) and 30 term-born control children aged seven to twelve years. The automated method FreeSurfer was used to obtain cortical thickness and cortical surface area measures from T1-weighted MRI images. Regional cortical thickness differed between groups but differences disappeared when controlling for age. Global cortical thickness differed between groups in the right hemisphere (very preterm children>controls). No group differences occurred for cortical surface area. The relationship between cortical morphometry and cognition differed between very preterm and control children. In very preterm children, some cognitive domains correlated positively and others negatively with regional cortical thickness and cortical surface area. Our findings contribute to the understanding of the structure-function relationship in very preterm children and their term-born peers. They add to the notion that this relationship varies depending on the brain region and the cognitive function in question and suggest developmental differences between very preterm and term-born children.

A longitudinal study of associations between psychiatric symptoms and disorders and cerebral gray matter volumes in adolescents born very preterm

Background

Being born preterm with very low birthweight (VLBW ≤ 1500 g) poses a risk for cortical and subcortical gray matter (GM) abnormalities, as well as for having more psychiatric problems during childhood and adolescence than term-born individuals. The aim of this study was to investigate the relationship between cortical and subcortical GM volumes and the course of psychiatric disorders during adolescence in VLBW individuals.

Methods

We followed VLBW individuals and term-born controls (birth weight ≥10th percentile) from 15 (VLBW;controls n = 40;56) to 19 (n = 44;60) years of age. Of these, 30;37 individuals were examined longitudinally. Cortical and subcortical GM volumes were extracted from MRPRAGE images obtained with the same 1.5 T MRI scanner at both time points and analyzed at each time point with the longitudinal stream of the FreeSurfer software package 5.3.0. All participants underwent clinical interviews and were assessed for psychiatric symptoms and diagnosis (Schedule for Affective Disorders and Schizophrenia for School-age Children, Children’s Global Assessment Scale, Attention-Deficit/Hyperactivity Disorder Rating Scale-IV). VLBW adolescents were divided into two groups according to diagnostic status from 15 to 19 years of age: persisting/developing psychiatric diagnosis or healthy/becoming healthy.

Results

Reduction in subcortical GM volume at 15 and 19 years, not including the thalamus, was limited to VLBW adolescents with persisting/developing diagnosis during adolescence, whereas VLBW adolescents in the healthy/becoming healthy group had similar subcortical GM volumes to controls. Moreover, across the entire VLBW group, poorer psychosocial functioning was predicted by smaller subcortical GM volumes at both time points and with reduced GM volume in the thalamus and the parietal and occipital cortex at 15 years. Inattention problems were predicted by smaller GM volumes in the parietal and occipital cortex.

Conclusions

GM volume reductions in the parietal and occipital cortex as well as smaller thalamic and subcortical GM volumes were associated with the higher rates of psychiatric symptoms found across the entire VLBW group. Significantly smaller subcortical GM volumes in VLBW individuals compared with term-born peers might pose a risk for developing and maintaining psychiatric diagnoses during adolescence. Future research should explore the possible role of reduced cortical and subcortical GM volumes in the pathogenesis of psychiatric illness in VLBW adolescents.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-017-0793-0) contains supplementary material, which is available to authorized users.

Altered brain function, structure, and developmental trajectory in children born late preterm

BACKGROUND

Late preterm birth (34-36 wk gestation) is a common occurrence with potential for altered brain development.

METHODS

This observational cohort study compared children at age 6-13 y based on the presence or absence of the historical risk factor of late preterm birth. Children completed a battery of cognitive assessments and underwent magnetic resonance imaging of the brain.

RESULTS

Late preterm children (n = 52) demonstrated slower processing speed (P = 0.035) and scored more poorly in visual-spatial perception (P = 0.032) and memory (P = 0.007) than full-term children (n = 74). Parents of late preterm children reported more behavioral difficulty (P = 0.004). There were no group differences in cognitive ability or academic achievement. Imaging revealed similar intracranial volumes but less total tissue and more cerebrospinal fluid (P = 0.004) for late preterm children compared to full-term children. The tissue difference was driven by differences in the cerebrum (P = 0.028) and distributed across cortical (P = 0.051) and subcortical tissue (P = 0.047). Late preterm children had a relatively smaller thalamus (P = 0.012) than full-term children. Only full-term children demonstrated significant decreases in cortical tissue volume (P < 0.001) and thickness (P < 0.001) with age.

CONCLUSION

Late preterm birth may affect cognition, behavior, and brain structure well beyond infancy.

Infant Medical Trauma in the Neonatal Intensive Care Unit (IMTN): A Proposed Concept for Science and Practice

BACKGROUND

Trauma is an innately subjective experience ensuing from a deeply distressing event. Research has demonstrated that while the environment of the neonatal intensive care unit (NICU) is capable of providing extraordinary lifesaving measures following birth, the experience may be disruptive to several key aspects of early development, placing infants at risk for adverse behavioral, cognitive, and emotional outcomes.

PURPOSE

This article provides rationale for the concept of Infant Medical Trauma in the NICU (IMTN) as a means of describing this unique stress experience. A triad of cumulative early life NICU experiences (stress, parental separation, and pain) is proposed to influence an infant's swinging neurodevelopmental pendulum amid the potential outcomes of risk and resilience.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Creating language that describes the infant experience brings meaning and calls caregivers and parents to action to consider strategies that may improve long-term health. Actively seeking opportunities to decrease the allostatic load of at-risk infants may support an infant's pendulum to swing toward a path of resilience, thereby moderating his or her early life adverse experience.

Diffusion tensor imaging and behavior in premature infants at 8 years of age, a randomized controlled trial with long-chain polyunsaturated fatty acids

BACKGROUND

Very low birth weight (VLBW, birth weight<1500 g) children have increased risk of behavioral problems. Diffusion tensor imaging (DTI) of the brain shows reduced white matter maturation. Long-chain polyunsaturated fatty acids are hypothesized to improve both myelination and behavioral outcome.

AIMS

To test the hypothesis that postnatal supplementation with docosahexaenoic acid (DHA) and arachidonic acid (AA) to very low birth weight infants would influence cerebral white matter measured by DTI and improve behavioral outcome at 8 years of age.

STUDY DESIGN

Eight-year follow-up of a randomized, double-blinded, placebo-controlled study of postnatal supplementation with DHA and AA to 129 VLBW infants fed human milk.

SUBJECTS

Ninety-eight children (76%) met for follow-up at 8 years.

OUTCOME MEASURES

Cerebral white matter measured by DTI. Behavioral outcome measured by Strengths and Difficulties questionnaire and selected scales from the Child Behavior Checklist.

RESULTS

No significant differences between the intervention group and the control group were found on white matter microstructure or behavioral data. A non-significant finding of higher fractional anisotropy (FA) in a cluster in the corpus callosum of the intervention group is discussed.

CONCLUSIONS

The present study is the first long-term follow-up of a randomized controlled trial with DHA and AA to human milk fed VLBW infants exploring cerebral white matter microstructure measured by DTI and parent-reported behavioral problems. No effects on white matter microstructure or behavioral outcome were observed at 8 years of age.

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, ≤1500 g) 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=8 years). 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.

[Formula: see text]Gestational age and gender influence on executive control and its related neural structures in preterm-born children at 6 years of age

Within preterm-born children, being born male and at a lower gestational age (GA) have both been associated with a heightened risk for developmental difficulties. However, in this population little is known about the combined effect and the influence of these risk factors on cortical structures and executive control. In the present study, 58 preterm-born children (GA ranging from 24.0 to 35.1 weeks) were administered the computerized Child Attention Network Task at 6 years of age. Brain magnetic resonance imaging was performed and analyzed using Voxel-Based Morphometry (VBM) in all children. At a behavioral level, boys born <28 weeks of GA had significantly less executive control than preterm-born girls <28 weeks (p = .001) and preterm-born boys ≥28 (p = .003). The reduced executive control in preterm-born boys <28 weeks gestation was related to lower cortical densities in the inferior frontal gyrus (IFG) and dorsolateral prefrontal cortex (DLPFC). The current study links the higher incidence of reduced executive control in preterm-born boys to a higher degree of prematurity (low GA) and identifies brain structural abnormalities in the prefrontal cortex related to these deficits. The implications of these results are discussed.

Disconnected neuromagnetic networks in children born very preterm: Disconnected MEG networks in preterm children

Many children born very preterm (≤32 weeks) experience significant cognitive difficulties, but the biological basis of such problems has not yet been determined. Functional MRI studies have implicated altered functional connectivity; however, little is known regarding the spatiotemporal organization of brain networks in this population. We provide the first examination of resting-state neuromagnetic connectivity mapped in brain space in school age children born very preterm. Thirty-four subjects (age range 7–12 years old), consisting of 17 very preterm-born children and 17 full-term born children were included. Very preterm-born children exhibited global decreases in inter-regional synchrony in all analysed frequency ranges, from theta (4–7 Hz) to high gamma (80–150 Hz; p < 0.01, corrected). These reductions were expressed in spatially and frequency specific brain networks (p < 0.0005, corrected). Our results demonstrate that mapping connectivity with high spatiotemporal resolution offers new insights into altered organization of neurophysiological networks which may contribute to the cognitive difficulties in this vulnerable population.

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We recorded resting-state magnetoencephalography in school-age children born very preterm and healthy children.

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We examine functional connectivity across a wide frequency spectrum in brain space.

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Global reductions in neural synchrony were detected in children born very preterm.

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These reductions encompass networks related to executive function and overall cognitive flexibility.

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These effects may be relevant to cognitive and behavioural difficulties reported in the ex-preterm population.

Long-chain polyunsaturated fatty acids and cognition in VLBW infants at 8 years: an RCT

OBJECTIVE

To test the hypothesis that supplementation with the long chain polyunsaturated fatty acids docosahexaenoic acid (DHA) and arachidonic acid (AA) to very low birth weight (VLBW) infants would improve long-term cognitive functions and influence neuroanatomical volumes and cerebral cortex measured by MRI.

METHODS

The current study is a follow-up of a randomized, double-blinded, placebo-controlled study of supplementation with high-dose DHA (0.86%) and AA (0.91%) to 129 VLBW infants fed human milk. Ninety-eight children participated at 8 years follow-up and completed a broad battery of cognitive tests. Eighty-one children had cerebral MRI scans of acceptable quality.

RESULTS

There were no significant differences between the intervention group and the control group on any of the cognitive measures. Equally, MRI data on segmental brain volumes and cerebral cortex volume, area, and thickness suggested no overall group effect.

CONCLUSIONS

This study is the first long-term follow-up of a randomized controlled trial with supplementation of DHA and AA to human milk fed VLBW infants investigating both cognitive functions and brain macrostructure measured by MRI. No cognitive or neuroanatomical effects of the supplementation were detected at 8 years of age.

Visual-motor deficits relate to altered gray and white matter in young adults born preterm with very low birth weight

Individuals born preterm and at very low birth weight (birth weight ≤ 1500 g) are at an increased risk of perinatal brain injury and neurodevelopmental deficits over the long term. This study examined whether this clinical group has more problems with visual-motor integration, motor coordination, and visual perception compared to term-born controls, and related these findings to cortical surface area and thickness and white matter fractional anisotropy. Forty-seven preterm-born very low birth weight individuals and 56 term-born controls were examined at 18-22 years of age with a combined cognitive, morphometric MRI, and diffusion tensor imaging evaluation in Trondheim, Norway. Visual-motor skills were evaluated with the Beery-Buktenica Developmental Test of Visual-Motor Integration-V (VMI) copying test and its supplemental tests of motor coordination and visual perception. 3D T1-weighted MPRAGE images and diffusion tensor imaging were done at 1.5 T. Cortical reconstruction generated in FreeSurfer and voxelwise maps of fractional anisotropy calculated with Tract-Based Spatial Statistics were used to explore the relationship between MRI findings and cognitive results. Very low birth weight individuals had significantly lower scores on the copying and motor coordination tests compared with controls. In the very low birth weight group, VMI scores showed significant positive relationships with cortical surface area in widespread regions, with reductions of the superior temporal gyrus, insula, and medial occipital lobe in conjunction with the posterior ventral temporal lobe. Visual perception scores also showed positive relationships with cortical thickness in the very low birth weight group, primarily in the lateral occipito-temporo-parietal junction, the superior temporal gyrus, insula, and superior parietal regions. In the very low birth weight group, visual-motor performance correlated positively with fractional anisotropy especially in the corpus callosum, inferior fronto-occipital fasciculus bilaterally, and anterior thalamic radiation bilaterally, driven primarily by an increase in radial diffusivity. VMI scores did not demonstrate a significant relationship to cortical surface area, cortical thickness, or diffusion measures in the control group. Our results indicate that visual-motor integration problems persist into adulthood for very low birth weight individuals, which may be due to structural alterations in several specific gray-white matter networks. Visual-motor deficits appear related to reduced surface area of motor and visual cortices and disturbed connectivity in long association tracts containing visual and motor information. We conjecture that these outcomes may be due to perinatal brain injury or aberrant cortical development secondary to injury or due to very preterm birth.

[The hearing function in the premature infants]

The present review of the literature is focused on the morphological and functional aspects of antenatal ontogenesis of the hearing system with special reference to the peculiar features of its formation during the post-natal period in the premature infants. In this context, the results of the objective psychoacoustic investigation s are considered (including those obtained by such methods as threshold audiometry, verbal and non-verbal tests, evaluation of central auditory processing of the sound information). Also presented are the results of the objective methods of hearing investigations (acoustic impedancometry, registration of optoacoustic emission and auditory evoked potentials). The underdevelopment of the hearing system in the premature infants manifests itself as the specific functional features of all its components. Their parameters are presented with reference to dynamics of their formation. In addition, the problem of central auditory processing of the disorders that are very likely to be present in the premature infants are discussed.

Early repetitive pain in preterm infants in relation to the developing brain

Infants born preterm (<37 weeks of gestation) are particularly vulnerable to procedural stress and pain exposure during neonatal intensive care, at a time of rapid and complex brain development. Concerns regarding effects of neonatal pain on brain development have long been expressed. However, empirical evidence of adverse associations is relatively recent. Thus, many questions remain to be answered. This review discusses the short- and long-term effects of pain-related stress and associated treatments on brain maturation and neurodevelopmental outcomes in children born preterm. The current state of the evidence is presented and future research directions are proposed.

Altered gray matter volume and school age anxiety in children born late preterm

OBJECTIVES

To determine if late preterm (LP) children differ from full term (FT) children in volumes of the cortex, hippocampus, corpus callosum, or amygdala and whether these differences are associated with anxiety symptoms at school-age.

STUDY DESIGN

LP children born between 34 and 36 weeks gestation and FT children born between 39 and 41 weeks gestation from a larger longitudinal cohort had magnetic resonance imaging scans at school-age. Brain volumes, cortical surface area, and thickness measures were obtained. Anxiety symptoms were assessed using a structured diagnostic interview annually beginning at preschool-age and following the magnetic resonance imaging.

RESULTS

LP children (n = 21) had a smaller percentage of total, right parietal, and right temporal lobe gray matter volume than FT children (n = 87). There were no differences in hippocampal, callosal, or amygdala volumes or cortical thickness. LP children also had a relative decrease in right parietal lobe cortical surface area. LP children had greater anxiety symptoms over all assessments. The relationship between late prematurity and school-age anxiety symptoms was mediated by the relative decrease in right temporal lobe volume.

CONCLUSIONS

LP children, comprising 70% of preterm children, are also at increased risk for altered brain development particularly in the right temporal and parietal cortices. Alterations in the right temporal lobe cortical volume may underlie the increased rate of anxiety symptoms among these LP children. These findings suggest that LP delivery may disrupt temporal and parietal cortical development that persists until school-age with the right temporal lobe conferring risk for elevated anxiety symptoms.

Delay of cortical thinning in very preterm born children

BACKGROUND

Cortical gray matter thinning occurs during childhood due to pruning of inefficient synaptic connections and an increase in myelination. Preterms show alterations in brain structure, with prolonged maturation of the frontal lobes, smaller cortical volumes and reduced white matter volume. These findings give rise to the question if there is a differential influence of age on cortical thinning in preterms compared to controls.

AIMS

To investigate the relationship between age and cortical thinning in school-aged preterms compared to controls.

STUDY DESIGN AND OUTCOME MEASURES

The automated surface reconstruction software FreeSurfer was applied to obtain measurements of cortical thickness based on T1-weighted MRI images.

SUBJECTS

Forty-one preterms (<32weeks gestational age and/or <1500g birth weight) and 30 controls were included in the study (7-12years).

RESULTS

In preterms, age correlated negatively with cortical thickness in right frontal, parietal and inferior temporal regions. Furthermore, young preterms showed a thicker cortex compared to old preterms in bilateral frontal, parietal and temporal regions. In controls, age was not associated with cortical thickness.

CONCLUSION

In preterms, cortical thinning still seems to occur between the age of 7 and 12years, mainly in frontal and parietal areas whereas in controls, a substantial part of cortical thinning appears to be completed before they reach the age of 7years. These data indicate slower cortical thinning in preterms than in controls.

Social attribution skills of children born preterm at very low birth weight

Children born prematurely at very low birth weight (<1500 g) are at increased risk for impairments affecting social functioning, including autism spectrum disorders (e.g., Johnson et al., 2010). In the current study, we used the Happé-Frith animated triangles task (Abell, Happé, & Frith, 2000) to study social attribution skills in this population. In this task, typical viewers attribute intentionality and mental states to shapes, based on characteristics of their movements. Participants included 34 preterm children and 36 full-term controls, aged 8-11 years. Groups were comparable in terms of age at test, gender, handedness, and socioeconomic status; they also performed similarly on tests of selective attention/processing speed and verbal intelligence. Relative to full-term peers, preterm children's descriptions of the animations were less appropriate overall; they also overattributed intentionality/mental states to randomly moving shapes and underattributed intentionality/mental states to shapes that seemed to be interacting socially. Impairments in the ability to infer the putative mental states of triangles from movement cues alone were most evident in children displaying more "autistic-like" traits, and this may reflect atypical development of and/or functioning in, or atypical connections between, parts of the social brain.

Much ado about norming: the Behavior Rating Inventory of Executive Function

The Behavior Rating Inventory of Executive Function (BRIEF) is a rating scale designed to assess executive functions in everyday life that is widely used in school and clinical settings and in research studies. It has been recently suggested, however, that the limited geographic stratification of the standardization sample renders the measure overly sensitive. We evaluated this hypothesis by examining BRIEF scores across studies of typically developing children and adolescents. Thirty-nine studies were identified that included at least one of three possible index scores. Mean scores across studies were (a) within one to two T-score units from the standardization sample mean of 50, (b) tended to be slightly lower than 50, and (c) were unrelated to geographic location (US Census regions or internationally). These findings refute recent claims that the BRIEF is overly sensitive and further add to the large body of literature supporting the validity of the measure.

Neonatal pain-related stress predicts cortical thickness at age 7 years in children born very preterm

Background

Altered brain development is evident in children born very preterm (24–32 weeks gestational age), including reduction in gray and white matter volumes, and thinner cortex, from infancy to adolescence compared to term-born peers. However, many questions remain regarding the etiology. Infants born very preterm are exposed to repeated procedural pain-related stress during a period of very rapid brain development. In this vulnerable population, we have previously found that neonatal pain-related stress is associated with atypical brain development from birth to term-equivalent age. Our present aim was to evaluate whether neonatal pain-related stress (adjusted for clinical confounders of prematurity) is associated with altered cortical thickness in very preterm children at school age.

Methods

42 right-handed children born very preterm (24–32 weeks gestational age) followed longitudinally from birth underwent 3-D T1 MRI neuroimaging at mean age 7.9 yrs. Children with severe brain injury and major motor/sensory/cognitive impairment were excluded. Regional cortical thickness was calculated using custom developed software utilizing FreeSurfer segmentation data. The association between neonatal pain-related stress (defined as the number of skin-breaking procedures) accounting for clinical confounders (gestational age, illness severity, infection, mechanical ventilation, surgeries, and morphine exposure), was examined in relation to cortical thickness using constrained principal component analysis followed by generalized linear modeling.

Results

After correcting for multiple comparisons and adjusting for neonatal clinical factors, greater neonatal pain-related stress was associated with significantly thinner cortex in 21/66 cerebral regions (p-values ranged from 0.00001 to 0.014), predominately in the frontal and parietal lobes.

Conclusions

In very preterm children without major sensory, motor or cognitive impairments, neonatal pain-related stress appears to be associated with thinner cortex in multiple regions at school age, independent of other neonatal risk factors.