Gender differences in language and motor-related fibers in a population of healthy preterm neonates at term-equivalent age: a diffusion tensor and probabilistic tractography study

Sex differences in neural processing of speech in neonates

The large majority of studies shows that girls develop their language skills faster than boys in the first few years of life. Are girls born with this advantage in language development? The present study used fNIRS in neonates to investigate sex differences in neural processing of speech within the first days of life. We found that speech stimuli elicited significantly more brain activity than non-speech stimuli in both groups of male and female neonates. However, whereas girls showed significant HbO changes to speech stimuli only within the left hemisphere, boys exhibited simultaneous neural activations in both hemispheres, with a larger and more significant fronto-temporal cluster in the right hemisphere. Furthermore, in boys, the variation in time-to-peak latencies was considerably greater than in girls. These findings suggest an earlier maturation of language-related brain areas in girls and highlight the importance of sex-specific investigations of neural language networks in infants.

Motor Skills of 5-Year-Old Children: Gender Differences and Activity and Family Correlates

It is unclear why there may be gender differences in the motor skills of same aged children. We compared motor skill competence of 5-year-old boys and girls ( n = 712) and examined whether variations in time spent in different types of activities and in family-related variables were associated with motor skills. We measured motor skills with the Bruininks–Oseretsky Test, Second Edition short form, and we used parental questionnaires to measure behavioral and family-related variables. Girls outperformed boys on most motor skills tasks, as eight of 14 tests showed statistically significant gender differences ( p <  .001). In addition, drawing or doing handicrafts for 60 minutes or more per day was positively associated with fine motor control ( p <  .001). Father’s higher education was associated with the children’s better body coordination ( p =  .020). Finally, both attending day care ( p =  .017) and outdoor physical activity for 60 minutes or more per day ( p =  .034) were positively associated with strength and agility. We found no associations between manual coordination and either daily activities or family-related variables. Time spent in different activities of young children should be recognized as a means of enhancing the development of fundamental motor skills.

Sex differences in brain connectivity and male vulnerability in very preterm children

Evidence indicates better cognitive and behavioral outcomes for females born very preterm (≤32 weeks gestation) compared to males, but the neurophysiology underlying this apparent resiliency of the female brain remains poorly understood. Here we test the hypothesis that very preterm males express more pronounced connectivity alterations as a reflection of higher male vulnerability. Resting state MEG recordings, neonatal and psychometric data were collected from 100 children at age 8 years: very preterm boys (n = 27), very preterm girls (n = 34), full‐term boys (n = 15) and full‐term girls (n = 24). Neuromagnetic source dynamics were reconstructed from 76 cortical brain regions. Functional connectivity was estimated using inter‐regional phase‐synchronization. We performed a series of multivariate analyses to test for differences across groups as well as to explore relationships between deviations in functional connectivity and psychometric scores and neonatal factors for very preterm children. Very preterm boys displayed significantly higher (p < .001) absolute deviation from average connectivity of same‐sex full‐term group, compared to very preterm girls versus full‐term girls. In the connectivity comparison between very preterm and full‐term groups separately for boys and girls, significant group differences (p < .05) were observed for boys, but not girls. Sex differences in connectivity (p < .01) were observed in very preterm children but not in full‐term groups. Our findings indicate that very preterm boys have greater alterations in resting neurophysiological network communication than girls. Such uneven brain communication disruption in very preterm boys and girls suggests that stronger connectivity alterations might contribute to male vulnerability in long‐term behavioral and cognitive outcome.

TRActs constrained by UnderLying INfant anatomy (TRACULInA): An automated probabilistic tractography tool with anatomical priors for use in the newborn brain

The ongoing myelination of white-matter fiber bundles plays a significant role in brain development. However, reliable and consistent identification of these bundles from infant brain MRIs is often challenging due to inherently low diffusion anisotropy, as well as motion and other artifacts. In this paper we introduce a new tool for automated probabilistic tractography specifically designed for newborn infants. Our tool incorporates prior information about the anatomical neighborhood of white-matter pathways from a training data set. In our experiments, we evaluate this tool on data from both full-term and prematurely born infants and demonstrate that it can reconstruct known white-matter tracts in both groups robustly, even in the presence of differences between the training set and study subjects. Additionally, we evaluate it on a publicly available large data set of healthy term infants (UNC Early Brain Development Program). This paves the way for performing a host of sophisticated analyses in newborns that we have previously implemented for the adult brain, such as pointwise analysis along tracts and longitudinal analysis, in both health and disease.

Interhemispherical Anatomical Disconnection in Disorders of Consciousness Patients

In patients with disorder of consciousness (DOC), the corpus callosum (CC) and subcortical white matter (SWM) integrity were shown to discriminate between diagnostic categories. The aims of the study were: (1) to clarify the link between the integrity of CC and of SWM and the clinical status in DOC patients, disentangling the role played by the different brain injuries (traumatic or hemorrhagic brain injury); (2) to investigate the relationship between the CC integrity and the brain metabolism. We assessed the diagnostic accuracy of the CC and SWM integrity, using diffusion tensor imaging (DTI) and structural magnetic resonance imaging (sMRI), in a sample of DOC individuals, well balanced for diagnosis and etiology. The CC DTI-derived measures were correlated with the brain metabolism, computed with fluorodeoxyglucose positron emission tomography. Our results showed that the CC macrostructural DTI-derived measures discriminate between diagnosis and correlate with the clinical status of DOC patients irrespective of the etiology. Moreover, the CC DTI-derived measures strongly correlate with the metabolism of the right hemisphere. No significant diagnostic accuracy emerged for the CC sMRI evaluation and the SWM measures. Our results indicate that: (1) the degree of the interhemispherical anatomical disconnection is a marker of the level of consciousness independent from the type of brain injury; (2) CC alterations might be the consequence of the reduced brain metabolism. Remarkably, our results suggest that the functional interplay between the two hemispheres is linked tightly to the level of consciousness.

Early assessment of lateralization and sex influences on the microstructure of the white matter corticospinal tract in healthy term neonates

We assessed the sex and the lateralization differences in the corticospinal tract (CST) during the early postnatal period. Twenty-five healthy term neonates (13 girls, aged 39.2 ± 1.2 weeks, and 12 boys aged 38.6 ± 3.0 weeks) underwent Diffusion Tensor Imaging (DTI). Fiber tracking was performed to extract bilaterally the CST pathways and to quantify the parallel (E₁ ) and perpendicular (E₂₃ ) diffusions, the apparent diffusion coefficient (ADC), and fractional anisotropy (FA). The measurements were performed on the entire CST fibers and on four segments: base of the pons (CST-Po), cerebral peduncles (CST-CP), posterior limb of the internal capsule (CST-PLIC), and corona-radiata (CST-CR). Significantly higher E₁ , lower E_23, and higher FA in the right compared to the left were noted in the CST-PLIC of the girls. Significantly lower E₂₃ and lower ADC with higher FA in the right compared to left were observed in the CST-CP of the boys. Moreover, the CST-PLIC of the boys had significantly higher E₁ in the right compared to the left. There was a significant increase in left CST E₁ of boys when compared with girls. Girls had a significantly lower E₁ , lower E₂₃ and, lower ADC in the left CST-CP compared with boys. In addition, girls had a significantly lower E₂₃ and higher FA in the right CST-PLIC compared with boys. Sex differences and lateralization in structure-based segments of the CST were found in healthy term infants during early postnatal period. These findings are vital to understanding motor development of healthy term born neonates to better interpret newborn infants with abnormal neurodevelopment.

Diffusion MRI parameters of corpus callosum and corticospinal tract in neonates: Comparison between region-of-interest and whole tract averaged measurements

PURPOSE

Measures of white matter (WM) microstructure inferred from diffusion magnetic resonance imaging (dMRI) are useful for studying brain development. There is uncertainty about agreement between FA and MD values obtained from region-of-interest (ROI) versus whole tract approaches. We investigated agreement between dMRI measures using ROI and Probabilistic Neighbourhood Tractography (PNT) in genu of corpus callosum (gCC) and corticospinal tracts (CST).

MATERIALS AND METHODS

81 neonates underwent 64 direction DTI at term equivalent age. FA and MD values were extracted from a 8 mm³ ROI placed within the gCC, right and left posterior limbs of internal capsule. PNT was used to segment gCC and CSTs to calculate whole tract-averaged FA and MD. Agreement between values obtained by each method was compared using Bland-Altman statistics and Pearson's correlation.

RESULTS

Across the 3 tracts the mean difference in FA measured by PNT and ROI ranged between 0.13 and 0.17, and the 95% limits of agreement did not include the possibility of no difference. For MD, the mean difference in values obtained from PNT and ROI ranged between 0.101 and 0.184 mm²/s × 10^-3 mm²/s: the mean difference in gCC was 0.101 × 10^-3 mm²/s with 95% limits of agreement that included the possibility of no difference, but there was significant disagreement in MD values measured in the CSTs.

CONCLUSION

Agreement between dMRI measures of neonatal WM microstructure calculated from ROI and whole tract averaged methods is weak. ROI approaches may not provide sufficient representation of tract microstructure at the level of neural systems in newborns.

Does Physical Fitness Affect Academic Achievement among Japanese Adolescents? A Hybrid Approach for Decomposing Within-Person and Between-Persons Effects

Positive association between physical fitness and academic achievement in adolescents has been suggested yet the causal effect of physical fitness on academic achievement remains unclear. This study examined if longitudinal changes in physical fitness were associated with changes in academic achievement among junior high school students. Analyses were based on a two-year with three time-point data of 567 students (aged 12–13 years old at the baseline-point; 303 boys) who entered in five Japanese junior high schools in 2015. Academic achievement was evaluated using the student’s overall grade point average. Comprehensive physical fitness score was summed up from eight fitness tests: 50-m sprint, standing broad jump, repeated side-steps, sit and reach, sit-ups, hand-grip strength, handball throw, and 20-m shuttle run or endurance run. The hybrid regression model was applied to examine the impact of change in physical fitness on change in academic achievement using multiple imputation to account for non-response at follow-up. The changes in fitness score within-person and the differences in average of fitness score of three-time points between-person were associated with change in overall grade point average for boys. No significant association between fitness score and overall grade point average was observed in girls. Opportunities for increased physical fitness may be important to support academic achievement, particularly in junior high school boys.

Imaging structural and functional brain development in early childhood

In humans, the period from term birth to ∼2 years of age is characterized by rapid and dynamic brain development and plays an important role in cognitive development and risk of disorders such as autism and schizophrenia. Recent imaging studies have begun to delineate the growth trajectories of brain structure and function in the first years after birth and their relationship to cognition and risk of neuropsychiatric disorders. This Review discusses the development of grey and white matter and structural and functional networks, as well as genetic and environmental influences on early-childhood brain development. We also discuss initial evidence regarding the usefulness of early imaging biomarkers for predicting cognitive outcomes and risk of neuropsychiatric disorders.

Impairments of motor function among children with a familial risk of schizophrenia or bipolar disorder at 7 years old in Denmark: an observational cohort study

BACKGROUND

Owing to the genetic overlap between schizophrenia and bipolar disorder, we aimed to assess domain-specific motor aberrations and disorder specificity among 7-year-old children with a familial risk of schizophrenia or bipolar disorder by comparing children in familial risk groups with each other and with children not in these risk groups.

METHODS

In the Danish High Risk and Resilience Study, we established a cohort of 7-year-old children with no, one, or two parents with schizophrenia or bipolar disorder in Denmark between Jan 1, 2013, and Jan 31, 2016. We matched children of parents diagnosed with schizophrenia to children of parents without schizophrenia on the basis of their home address, age, and sex. Even though we did not match children of parents with bipolar disorder directly to controls because of resource constraints, we only recruited children into the three groups who did not differ in terms of age, sex, and urbanicity. We investigated motor function in children using the Movement Assessment Battery for Children-Second Edition. Motor function raters were masked to participants' clinical risk status during assessments. We assessed the effects of familial risk group in a mixed-model analysis with repeated measures with an unstructured variance component matrix.

FINDINGS

We studied 514 children (198 [39%] children of parents with schizophrenia, 119 [23%] of parents with bipolar disorder, and 197 [38%] of parents without schizophrenia or bipolar disorder). Children of parents with schizophrenia showed impaired motor performance compared with those of parents without in the subdomains of manual dexterity (mean difference -1·42 [95% CI -2·08 to -0·77]; p<0·0001) and balance (-1·38 [-2·03 to -0·72]; p<0·0001), but not of aiming and catching (-0·39 [-0·97 to 0·19]; p=0·18). Children of parents with bipolar disorder did not show any significant difference in motor performance to children of parents without in the subdomains of manual dexterity (-0·69 [-1·44 to 0·07]; p=0·08), balance (-0·68 [-1·44 to 0·08]; p=0·08), and aiming and catching (-0·36 [-1·03 to 0·31]; p=0·29). Comparison of familial risk groups of mental disorders revealed no significant differences in the subdomains of manual dexterity (-0·74 [-1·49 to 0·02]; p=0·06), balance (-0·70 [-1·46 to 0·06]; p=0·07), or aiming and catching (-0·03 [-0·70 to 0·63]; p=0·92).

INTERPRETATION

Motor abnormalities in children with a familial risk of schizophrenia are specific at 7 years of age with respect to fine motor function and balance, but non-specific with respect to familial risk of bipolar disorder. Clinicians should be aware of motor symptoms and refer children with definite motor problems (below the fifth percentile) to a child physiotherapist.

FUNDING

Mental Health Services of the Capital Region of Denmark, Aarhus University, and the Lundbeck Foundation Initiative for Integrative Psychiatric Research.

Moderate and late preterm infants exhibit widespread brain white matter microstructure alterations at term-equivalent age relative to term-born controls

Despite the many studies documenting cerebral white matter microstructural alterations associated with very preterm birth (<32 weeks' gestation), there is a dearth of similar research in moderate and late preterm infants (born 32-36 weeks' gestation), who experience higher rates of neurodevelopmental delays than infants born at term (≥ 37 weeks' gestation). We therefore aimed to determine whether whole brain white matter microstructure differs between moderate and late preterm infants and term-born controls at term-equivalent age, as well as to identify potential perinatal risk factors for white matter microstructural alterations in moderate and late preterm infants. Whole brain white matter microstructure was studied in 193 moderate and late preterm infants and 83 controls at term-equivalent age by performing Tract-Based Spatial Statistics analysis of diffusion tensor imaging data. Moderate and late preterm infants had lower fractional anisotropy and higher mean, axial and radial diffusivities compared with controls in nearly 70% of the brain's major white matter fiber tracts. In the moderate and late preterm group, being born small for gestational age and male sex were associated with lower fractional anisotropy, largely within the optic radiation, corpus callosum and corona radiata. In conclusion, moderate and late preterm infants exhibit widespread brain white matter microstructural alterations compared with controls at term-equivalent age, in patterns consistent with delayed or disrupted white matter microstructural development. These findings may underpin some of the neurodevelopmental delays observed in moderate and late preterm children.

Data quality in diffusion tensor imaging studies of the preterm brain: a systematic review

BACKGROUND

To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount.

OBJECTIVE

To review the literature to evaluate acquisition and processing methodology in diffusion tensor imaging studies of preterm infants.

MATERIALS AND METHODS

We searched the Embase, Medline, Web of Science and Cochrane databases for relevant papers published between 2003 and 2013. The following keywords were included in our search: prematurity, neuroimaging, brain, and diffusion tensor imaging.

RESULTS

We found 74 diffusion tensor imaging studies in preterm infants meeting our inclusion criteria. There was wide variation in acquisition and processing methodology, and we found incomplete reporting of these settings. Nineteen studies (26%) reported the use of neonatal hardware. Data quality assessment was not reported in 13 (18%) studies. Artefacts-correction and data-exclusion was not reported in 33 (45%) and 18 (24%) studies, respectively. Tensor estimation algorithms were reported in 56 (76%) studies but were often suboptimal.

CONCLUSION

Diffusion tensor imaging acquisition and processing settings are incompletely described in current literature, vary considerably, and frequently do not meet the highest standards.

Associations of motor and cardiovascular performance with academic skills in children

PURPOSE

We investigated the associations of cardiovascular and motor performance in grade 1 with academic skills in grades 1-3.

METHODS

The participants were 6- to 8-yr-old children with complete data in grades 1-2 for 174 children and in grade 3 for 167 children. Maximal workload during exercise test was used as a measure of cardiovascular performance. The shuttle run test (SRT) time, the errors in balance test, and the number of cubes moved in box and block test (BBT) were measures of motor performance. Academic skills were assessed using reading fluency, reading comprehension, and arithmetic skill tests.

RESULTS

Among boys, longer SRT time was associated with poorer reading fluency in grades 1-3 (β = -0.29 to -0.39, P < 0.01), reading comprehension in grades 1-2 (β = -0.25 to -0.29, P < 0.05), and arithmetic skills in grades 1-3 (β = -0.33 to -0.40, P < 0.003). Poorer balance was related to poorer reading comprehension (β = -0.20, P = 0.042). The smaller number of cubes moved in BBT was related to poorer reading fluency in grades 1-2 (β = 0.23-0.28, P < 0.03), reading comprehension in grade 3 (β = 0.23, P = 0.037), and arithmetic skills in grades 1-2 (β = 0.21-0.23, P < 0.043). Among girls, longer SRT time was related to poorer reading fluency in grade 3 (β = -0.27, P = 0.027) and arithmetic skills in grade 2 (β = -0.25, P = 0.040). The smaller number of cubes moved in BBT was associated with worse reading fluency in grade 2 (β = 0.26, P = 0.030). Cardiovascular performance was not related to academic skills.

CONCLUSIONS

Poorer motor performance was associated with worse academic skills in children, especially among boys. These findings emphasize early identification of children with poor motor performance and actions to improve these children's motor performance and academic skills during the first school years.

Early growth and neurodevelopmental outcome in very preterm infants: impact of gender

BACKGROUND AND OBJECTIVE

Nutrition in the neonatal unit may impact the neurological outcome of very preterm infants, and male preterms are more likely to suffer neonatal morbidity and adverse neurological outcomes. We hypothesised that growth during hospitalisation would impact neurological outcome differently, depending on infant gender.

METHODS

Surviving infants born between 1 January 2003 and 31 December 2009 with a gestational age <33 weeks, and enrolled in Loire Infant Follow-up Team, a regional cohort in western France, qualified for the study. Growth during neonatal hospitalisation was assessed by the change in weight z-score between birth and discharge, and infants where ranked into 5 classes, depending on their change in z-score (<-2, -2 to -1.01, -1 to -0.51, -0.50 to 0.01 and ≥0), the last class being the reference. The main outcome criterion was neurodevelopmental outcome at 2 years of corrected age. For each class of changes in weight z-score, crude or adjusted OR for non-optimal outcome was calculated for each gender, and compared between genders.

RESULTS

1221 boys and 1056 girls were included. Gender and early growth interact, (p=0.02). Moreover when change in weight z-score varied from <-2 to (-0.50 to -0.01), adjusted OR for non-optimal outcome varied from 3.2 (1.5-6.8) to 2.2 (1.2-4.1) in boys versus 1.8 (0.7-4.2) to 0.95 (0.4-1.9) in girls. For each class, the OR was significantly higher in boys.

CONCLUSIONS

In very preterm infants, male neurodevelopment appears to be much more sensitive than female to poor postnatal growth.

Magnetic resonance diffusion tractography of the preterm infant brain: a systematic review

AIM

Preterm birth is associated with an increased risk of adverse neurodevelopmental outcomes. Diffusion magnetic resonance imaging (dMRI) combined with tractography can be used to assess non-invasively white matter microstructure and brain development in preterm infants. Our aim was to conduct a systematic review of the current evidence obtained from tractography studies of preterm infants in whom MRI was performed up to term-equivalent age.

METHOD

Databases were searched for dMRI tractography studies of preterm infants.

RESULTS

Twenty-two studies were assessed. The most frequently assessed tracts included the corticospinal tract, the corpus callosum, and the optic radiations. The superior longitudinal fasciculus, and the anterior and superior thalamic radiations were investigated less frequently. A clear relationship exists between diffusion metrics and postmenstrual age at the time of scanning, although the evidence of an effect of gestational age at birth and white matter injury is conflicting. Sex and laterality may play an important role in the relationship between diffusion metrics, early clinical assessment, and outcomes.

INTERPRETATION

Studies involving infants of all gestational ages are required to elucidate the relationship between gestational age and diffusion metrics, and to establish the utility of tractography as a predictive tool. There is a need for more robust acquisition and analysis methods to improve the accuracy of assessing development of white matter pathways.

Differences in the maturation of amplitude-integrated EEG signals in male and female preterm infants

BACKGROUND

The amplitude-integrated electroencephalogram (aEEG) is a valuable tool for monitoring brain function in preterm infants. Several studies have discussed sex-related differences regarding neonatal morbidity and mortality. To date, no study has been published specifically evaluating potential sex-related differences in aEEG parameters.

OBJECTIVE

The aim of this study was to assess sex-related differences in aEEG signals in preterm born infants without brain injury in the first 4 weeks of life.

METHODS

aEEG was performed at seven time points (days 1, 2, 3, weeks 1, 2, 3 and 4) and analyzed for Burdjalov total score, number of bursts per hour and visual background pattern.

PATIENTS

One hundred and fifty-six infants (85 male and 71 female) born with a gestational age between 28 and 31 completed weeks were evaluated.

RESULTS

Mean total score increased with postnatal age and ranged from 5.4 at day 1 to 11.0 at the end of the study period. The score was higher for girls at every time point, and the mean difference was between 0.3 and 0.9. The number of bursts per hour decreased over time from 8.9 at day 1 to 1.6 at the end of the study period. At week 4, the number of bursts per hour was significantly lower in girls (1.3) than in boys (2.0).

CONCLUSION

Sex-related differences were present in aEEG signals of preterm infants. The lower total score and the higher number of bursts might express delayed brain maturation in male preterm infants.

Assessment of structural connectivity in the preterm brain at term equivalent age using diffusion MRI and T2 relaxometry: a network-based analysis

Preterm birth is associated with a high prevalence of adverse neurodevelopmental outcome. Non-invasive techniques which can probe the neural correlates underpinning these deficits are required. This can be achieved by measuring the structural network of connections within the preterm infant's brain using diffusion MRI and tractography. We used diffusion MRI and T₂ relaxometry to identify connections with altered white matter properties in preterm infants compared to term infants. Diffusion and T₂ data were obtained from 9 term neonates and 18 preterm-born infants (born <32 weeks gestational age) at term equivalent age. Probabilistic tractography incorporating multiple fibre orientations was used in combination with the Johns Hopkins neonatal brain atlas to calculate the structural network of connections. Connections of altered diffusivity or T₂, as well as their relationship with gestational age at birth and postmenstrual age at the time of MRI, were identified using the network based statistic framework. A total of 433 connections were assessed. FA was significantly reduced in 17, and T₂ significantly increased in 18 connections in preterm infants, following correction for multiple comparisons. Cortical networks associated with affected connections mainly involved left frontal and temporal cortical areas: regions which are associated with working memory, verbal comprehension and higher cognitive function – deficits which are often observed later in children and adults born preterm. Gestational age at birth correlated with T₂, but not diffusion in several connections. We found no association between diffusion or T₂ and postmenstrual age at the time of MRI in preterm infants. This study demonstrates that alterations in the structural network of connections can be identified in preterm infants at term equivalent age, and that incorporation of non-diffusion measures such as T₂ in the connectome framework provides complementary information for the assessment of brain development.

Motor profile of Portuguese preschool children on the Peabody Developmental Motor Scales-2: a cross-cultural study

This study was designed to examine the cultural sensitivity of the PDMS-2 for Portuguese preschool children aged 36-71 months. A total of 540 children (255 males and 285 females) from 15 public preschools of Viana do Castelo, Portugal, were assessed. Age and gender effects in motor performance were examined. Results indicated that PDMS-2 is valid instrument to differentiate Portuguese age groups. Girls presented higher scores than boys in the Grasping and Visuo-motor integration subtests and lower scores in the Object Manipulation subtest. Portuguese preschoolers performed above US norms on Grasping, Visual-motor integration, and Stationary subtests, and bellow on Locomotion and Object Manipulation subtests. Overall, Portuguese children showed better results on the Fine Motor Quotient comparing to the Gross Motor Quotient. These results underline different motor development profiles between Portuguese and American children.

Limitations on the developing preterm brain: impact of periventricular white matter lesions on brain connectivity and cognition

Brain lesions to the white matter in peritrigonal regions, periventricular leukomalacia, in children who were born prematurely represent an important model for studying limitations on brain development. The lesional pattern is of early origin and bilateral, that constrains the compensatory potential of the brain. We suggest that (i) topography and severity of periventricular lesions may have a long-term predictive value for cognitive and social capabilities in preterm birth survivors; and (ii) periventricular lesions may impact cognitive and social functions by affecting brain connectivity, and thereby, the dissociable neural networks underpinning these functions. A further pathway to explore is the relationship between cerebral palsy and cognitive outcome. Restrictions caused by motor disability may affect active exploration of surrounding and social participation that may in turn differentially impinge on cognitive development and social cognition. As an outline for future research, we underscore sex differences, as the sex of a preterm newborn may shape the mechanisms by which the developing brain is affected.

Nonlinear microstructural changes in the right superior temporal sulcus and lateral occipitotemporal gyrus between 35 and 43 weeks in the preterm brain

Using diffusion tensor imaging (DTI), we explored microstructural brain maturation in a population of 65 preterm neonates who underwent magnetic resonance imaging between 35 and 43 weeks of corrected gestational age. A voxel-based analysis approach, statistical parametric mapping (SPM8), was used to evidence the nonlinear changes with the corrected gestational age in the regional distribution of mean diffusivity (MD), fractional anisotropy (FA), longitudinal and transverse diffusivities (λ//and λ⊥). We found that FA changes nonlinearly with age around the right superior temporal sulcus and in the right lateral occipitotemporal gyrus, with FA decrease between 34 and 39 weeks followed by FA increase from 40 weeks to 43 weeks. Considering the key role of these brain areas in verbal and non-verbal communicative behaviors, the effect of these microstructural changes in terms of early social network functional maturation needs to be assessed by joint functional and anatomical studies.