Correlation between corpus callosum sub-segmental area and cognitive processes in school-age children

Corpus callosum long-term biometry in very preterm children related to cognitive and motor outcomes

BACKGROUND

The corpus callosum (CC) is suggested as an indirect biomarker of white matter volume, which is often affected in preterm birth. However, diagnosing mild white matter injury is challenging.

METHODS

We studied 124 children born preterm (mean age: 8.4 ± 1.1 years), using MRI to assess CC measurements and cognitive/motor outcomes based on the Wechsler Intelligence Scale for Children-V (WPPSI-V) and Movement Assessment Battery for Children-2 (MABC-2).

RESULTS

Children with normal outcomes exhibited greater height (10.2 ± 2.1 mm vs. 9.4 ± 2.3 mm; p = 0.01) and fractional anisotropy at splenium (895[680-1000] vs 860.5[342-1000]) and total CC length (69.1 ± 4.8 mm vs. 67.3 ± 5.1 mm; p = 0.02) compared to those with adverse outcomes. All measured CC areas were smaller in the adverse outcome group. Models incorporating posterior CC measurements demonstrated the highest specificity (83.3% Sp, AUC: 0.65) for predicting neurological outcomes. CC length and splenium height were the only linear measurements associated with manual dexterity and total MABC-2 score while both the latter and genu were related with Full-Scale Intelligence Quotient.

CONCLUSIONS

CC biometry in children born very preterm at school-age is associated with outcomes and exhibits a specific subregion alteration pattern. The posterior CC may serve as an important neurodevelopmental biomarker in very preterm infants.

IMPACT

The corpus callosum has the potential to serve as a reliable and easily measurable biomarker of white matter integrity in very preterm children. Estimating diffuse white matter injury in preterm infants using conventional MRI sequences is not always conclusive. The biometry of the posterior part of the corpus callosum is associated with cognitive and certain motor outcomes at school age in children born very preterm. Length and splenium measurements seem to serve as reliable biomarkers for assessing neurological outcomes in this population.

Precocious White Matter Inflammation and Behavioural Inflexibility Precede Learning and Memory Impairment in the TgAPP21 Rat Model of Alzheimer Disease

Neuroinflammation and behavioural inflexibility are both common in late adulthood but far more profound in Alzheimer disease (AD). To investigate the relationship between ageing, AD, neuroinflammation, and behavioural flexibility, male wild-type Fischer 344 (Wt) and the transgenic APP21 (TgAPP21) rats were aged to 4, 8, 13, and 22 months and evaluated for neuroinflammation and cognitive impairment. TgAPP21 rats overexpress a pathogenic variant of the human amyloid precursor protein (hAPP; Swedish and Indiana mutations) but do not spontaneously develop overt pathology related to AD. In both genotypes, learning and memory were similarly impaired in older rats. However, at 8 months of age, TgAPP21 rats demonstrated behavioural inflexibility in set shifting, reversal, and the Morris water maze, while Wt rats showed inflexibility at 13 and 22 months of age. This early inflexibility in TgAPP21 rats was accompanied by a precocious increase in microglia activation within the corpus callosum; 8- and 13-month-old TgAPP21 rats had similar levels of microglia activation as 13- and 22-month-old Wt rats, respectively. However, while neuroinflammation within the white matter continued to progress with age, behavioural inflexibility peaked in 8-month-old TgAPP21 rats; in older TgAPP21 rats, memory and learning impairments masked inflexibility. These findings suggest that the behavioural inflexibility and white matter inflammation seen in normal ageing are accelerated in AD and may precede impairments of learning and memory.

Childhood sleep disturbances and white matter microstructure in preadolescence

BACKGROUND

Sleep problems occur in up to 30% of children and have been associated with adverse developmental outcomes. However, due to a lack of longitudinal neuroimaging studies, the neurobiological changes that may underlie some of these associations have remained unclear. This study explored the association between sleep problems during childhood and white matter (WM) microstructure in preadolescence.

METHODS

Children from the population-based birth cohort, the Generation R Study, who had repeatedly assessed sleep problems between 1.5 and 10 years of age and a MRI scan at age 10 (N = 2,449), were included. Mothers reported on their child's sleep problems using the Child Behavior Checklist (CBCL 1.5-5) when children were 1.5, 3, and 6 years of age. At age 2, mothers completed very similar questions. At age 10, both children and their mothers reported on sleep problems. We used whole-brain and tract-specific fractional anisotropy (FA) and mean diffusivity (MD) values obtained through diffusion tensor imaging as measures of WM microstructure.

RESULTS

Childhood sleep problems at 1.5, 2, and 6 years of age were associated with less WM microstructural integrity (approximately 0.05 SD lower global FA score per 1-SD sleep problems). In repeated-measures analyses, children with more sleep problems (per 1-SD) at baseline had lower FA values at age 10 in particular in the corticospinal tract (-0.12 SD, 95% CI:-0.20;-0.05), the uncinate fasciculus (-0.12 SD, 95% CI:-0.19;-0.05), and the forceps major (-0.11 SD, 95% CI:-0.18;-0.03), although effect estimates across the tracts did not differ substantially.

CONCLUSIONS

Childhood sleep disturbances are associated with less WM microstructural integrity in preadolescence. Our results show that early neurodevelopment may be a period of particular vulnerability to sleep problems. This study cannot demonstrate causality but suggests that preventive interventions addressing sleep problems should be further explored to test whether they impact adverse neurodevelopment.

The neural code of intelligence: From correlation to causation

Research into the neural underpinning of intelligence has mainly adopted a construct perspective: trying to find structural and functional brain characteristics that would accommodate the psychological concept of g. Few attempts have been made to explain intelligence exclusively based on brain characteristics - the brain perspective. From a methodological viewpoint the brain intelligence relation has been studied by means of correlational and interventional studies. The later providing a causal elucidation of the brain - intelligence relation. The best neuro-anatomical predictor of intelligence is brain volume showing a modest positive correlation with g, explaining between 9 to 16% of variance. The most likely explanation was that larger brains, containing more neurons, have a greater computational power and in that way allow more complex cognitive processing. Correlations with brain surface, thickness, convolution and callosal shape showed less consistent patterns. The development of diffusion tensor imaging has allowed researchers to look also into the microstructure of brain tissue. Consistently observed was a positively correlation between white matter integrity and intelligence, supporting the idea that efficient information transfer between hemispheres and brain areas is crucial for higher intellectual competence. Based on functional studies of the brain intelligence relationship three theories have been put forward: the neural efficiency, the P-FIT and the multi demand (MD) system theory. On the other hand, The Network Neuroscience Theory of g, based on methods from mathematics, physics, and computer science, is an example for the brain perspective on neurobiological underpinning of intelligence. In this framework network flexibility and dynamics provide the foundation for general intelligence. With respect to intervention studies the most promising results have been achieved with noninvasive brain stimulation and behavioral training providing tentative support for findings put forward by the correlational approach. To date the best consensus based on the diversity of results reported would be that g is predominantly determined by lateral prefrontal attentional control of structured sensory episodes in posterior brain areas. The capacity of flexible transitions between these network states represents the essence of intelligence - g.

Cognitive function assessment and comparison on lateral ventricular tumors resection by the frontal transcortical approach and anterior transcallosal approach respectively in children

Currently, there are few studies on cognitive impairment caused by neurosurgery, and there have been no studies on cognitive impairment after resection of lateral ventricular tumors in children. Previously, our research team has reported that the frontal transcortical approach can impair cognitive function. In this study, we explored which functions would be damaged by the transcallosal approach and compared the cognitive function changes caused by the two surgical approaches, so as to provide a theoretical basis for the selection of pre-operative surgical approaches. The authors prospectively collected pediatric patients with lateral ventricular tumors who had undergone surgical resection through the frontal transcortical approach and anterior transcallosal approach in Beijing Tiantan Hospital from November 2012 to May 2017. The inclusion criteria according to the Children Wechsler Scale requirements and clinical performance were formulated. Wechsler Intelligence Scale for Children®-fourth edition: Chinese version (WISC-IV) was adopted for general intelligence and cognitive function assessment in the study. In addition, the resting-state functional magnetic resonance imaging (resting-state fMRI) and diffusion tensor imaging (DTI) were carried out to measure the level of co-activation and to explore the functional connectivity between the brain regions at the pre-operative period and 6-month follow-up in post-operation. A total of 30 patients were enrolled. Gross total resection was achieved in all patients, and no severe post-operative complications were observed. The frontal transcortical approach was applied in 19 patients, and the transcallosal approach was conducted for 11 patients. Compared with the pre-operative indices of WISC-IV, patients generally had a lower level of indices of the WISC-IV in post-operation. In patients accepting lateral ventricular tumors resection through the anterior transcallosal approach, the total IQ was declined to M = 84.82, SD = 8.072 from M = 93.27, SD = 6.635 within the 6-month convalescence. The data of working memory (t = - 2.990, p = 0.002) and total IQ (t = - 2.205, p = 0.028) pre- and post-operative showed statistical significance. But in the comparison of two surgical approaches, it was found that IQ had no statistical difference in WISC-IV tasks data. Previous studies suggest that the frontal transcortical approach impair perceptual reasoning, processing speed, and IQ, while this study indicates that the anterior transcallosal approach impairs patients' working memory and IQ. Both approaches make equal damage to IQ. Through comparing the two surgical approaches, it can be known that the anterior transcallosal approach cannot replace the frontal transcortical approach. The protection of cognitive function should be considered as one of the bases for neurosurgeons to select the operative approach before the operation. However, in an actual situation, the specific approach should be carefully selected by comprehensive consideration.

Normal Development of the Corpus Callosum and Evolution of Corpus Callosum Sexual Dimorphism in Infancy

OBJECTIVES

The aim of this study was to establish reference ranges for the corpus callosum in infancy and to clarify how sexual dimorphism evolves between the fetal stage and infancy.

METHODS

Normal sonograms from cerebral ultrasonographic examinations of 1- to 6-month-old healthy full-term infants were selected. The length and thickness of the corpus callosum were determined, and the effect of sex on these values was analyzed. Studies on corpus callosum sexual dimorphism were reviewed.

RESULTS

In total, sonograms from 236 1- to 6-month-old infants (120 male and 116 female) were collected, and the typical values (5th-95th percentiles) of the corpus callosum were determined for each group. During the first 2 months, with and without brain size adjustment, the corpus callosum in female infants was significantly thicker than that in male infants (mean thickness ± SD: 1 month, male infant, 1.8 ± 0.3 mm; female infant, 2.1 ± 0.3 mm; P = .005; 2 months, male infant, 1.8 ± 0.2 mm; female infant, 2.0 ± 0.3 mm; P = .002). The corpus callosum thickness of male and female infants had no significant differences after 2 months of age. Sexual dimorphism was not detected in corpus callosum length.

CONCLUSIONS

Our study provides reference data on typical corpus callosum development in infants. In the fetal period and early infancy, the corpus callosum in female infants is thicker than that in male infants. From 3 months onward, the corpus callosum sexual dimorphism becomes insignificant throughout childhood. The evolvement of corpus callosum sexual dimorphism suggests that maternal factors may influence brain development.

Resting state functional connectivity of the anterior striatum and prefrontal cortex predicts reading performance in school-age children

The current study investigated the neural basis of reading performance in 60 school-age Spanish-speaking children, aged 6 to 9years. By using a data-driven approach and an automated matching procedure, we identified a left-lateralized resting state network that included typical language regions (Wernicke's and Broca's regions), prefrontal cortex, pre- and post-central gyri, superior and middle temporal gyri, cerebellum, and subcortical regions, and explored its relevance for reading performance (accuracy, comprehension and speed). Functional connectivity of the left frontal and temporal cortices and subcortical regions predicted reading speed. These results extend previous findings on the relationship between functional connectivity and reading competence in children, providing new evidence about such relationships in previously unexplored regions in the resting brain, including the left caudate, putamen and thalamus. This work highlights the relevance of a broad network, functionally synchronized in the resting state, for the acquisition and perfecting of reading abilities in young children.

Biometry of the corpus callosum assessed by 3D ultrasound and its correlation to neurodevelopmental outcome in very low birth weight infants

OBJECTIVE

Several studies have shown a relation between the size of corpus callosum (CC) and outcome in preterm infants. Three-dimensional ultrasound (3D-US) offers new perspectives in cerebral imaging. To establish reference values for biometry of the CC in very low birth weight infants and to correlate these measurements to neurodevelopmental outcome at 5 years of age.

STUDY DESIGN

Forty-three preterm infants with a gestational age <32 weeks were included. Transfontanellar 3D-US measurements were obtained at nine different timepoints.

RESULTS

3D-US-based reference values for size, length, circumference and surface area of the CC could be established. Measurements at term-equivalent age showed a correlation to neurodevelopment outcome.

CONCLUSION

Reliable biometric data of the CC can be established in preterm infants by 3D-US and correlate with neurodevelopmental outcome.

Making Brains run Faster: are they Becoming Smarter?

A brief overview of structural and functional brain characteristics related to g is presented in the light of major neurobiological theories of intelligence: Neural Efficiency, P-FIT and Multiple-Demand system. These theories provide a framework to discuss the main objective of the paper: what is the relationship between individual alpha frequency (IAF) and g? Three studies were conducted in order to investigate this relationship: two correlational studies and a third study in which we experimentally induced changes in IAF by means of transcranial alternating current stimulation (tACS). (1) In a large scale study (n = 417), no significant correlations between IAF and IQ were observed. However, in males IAF positively correlated with mental rotation and shape manipulation and with an attentional focus on detail. (2) The second study showed sex-specific correlations between IAF (obtained during task performance) and scope of attention in males and between IAF and reaction time in females. (3) In the third study, individuals’ IAF was increased with tACS. The induced changes in IAF had a disrupting effect on male performance on Raven’s matrices, whereas a mild positive effect was observed for females. Neuro-electric activity after verum tACS showed increased desynchronization in the upper alpha band and dissociation between fronto-parietal and right temporal brain areas during performance on Raven’s matrices. The results are discussed in the light of gender differences in brain structure and activity.