No abstract

No abstract

Neural communication is facilitated by intricate networks of white matter (WM) comprised of both long and short range connections. The maturation of long range WM connections has been extensively characterized, with projection, commissural, and association tracts showing unique trajectories with age. There, however, remains a limited understanding of age-related changes occurring within short range WM connections, or U-fibers. These connections are important for local connectivity within lobes and facilitate regional cortical function and greater network economy. Recent studies have explored the maturation of U-fibers primarily using cross-sectional study designs. Here, we analyzed diffusion tensor imaging (DTI) data for healthy children and adolescents in both a cross-sectional (n 5 78; mean age 5 13.04 6 3.27 years) and a primarily longitudinal (n 5 26; mean age 5 10.78 6 2.69 years) cohort. We found significant age-related differences in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) across the frontal, parietal, and temporal lobes of participants within the cross-sectional cohort. By contrast, we report significant age-related differences in only FA for participants within the longitudinal cohort. Specifically, larger FA values were observed with age in frontal, parietal, and temporal lobes of the left hemisphere. Our results extend previous findings restricted to long range WM to demonstrate regional changes in the microstructure of short range WM during childhood and adolescence. These changes possibly reflect continued myelination and axonal organization of short range WM with increasing age in more anterior regions of the left hemisphere. Hum Brain Mapp 39:204-217, 2018. Key words: short-range WM; DTI; white matter maturation; linear mixed effects model r rAdditional Supporting Information may be found in the online version of this article.

No abstract

Facial emotion recognition (FER) deficits are evident and pervasive across neurodevelopmental, psychiatric, and acquired brain disorders in children, including children treated for brain tumours. Such deficits are thought to perpetuate challenges with social relationships and decrease quality of life. The present study combined eye-tracking, neuroimaging and cognitive assessments to evaluate if visual attention, brain structure, and general cognitive function contribute to FER in children treated for posterior fossa (PF) tumours (patients: n = 36) and typically developing children (controls: n = 18). To assess FER, all participants completed the Diagnostic Analysis of Nonverbal Accuracy (DANVA2), a computerized task that measures FER using photographs, while their eye-movements were recorded. Patients made more FER errors than controls ( p < .01). Although we detected subtle deficits in visual attention and general cognitive function in patients, we found no associations with FER. Compared to controls, patients had evidence of white matter (WM) damage, (i.e., lower fractional anisotropy [FA] and higher radial diffusivity [RD]), in multiple regions throughout the brain (all p < .05), but not in specific WM tracts associated with FER. Despite the distributed WM differences between groups, WM predicted FER in controls only. In patients, factors associated with their disease and treatment predicted FER. Our study provides insight into predictors of FER that may be unique to children treated for PF tumours, and highlights a divergence in associations between brain structure and behavioural outcomes in clinical and typically developing populations; a concept that may be broadly applicable to other neurodevelopmental and clinical populations that experience FER deficits.

Objective: Children treated for brain tumors often experience social and emotional difficulties, including challenges with emotion regulation; our goal was to investigate the attention-related component processes of emotion regulation, using a novel eye-tracking measure, and to evaluate its relations with emotional functioning and white matter (WM) organization. Method: Fifty-four children participated in this study; 36 children treated for posterior fossa tumors, and 18 typically developing children. Participants completed two versions of an emotion regulation eye-tracking task, designed to differentiate between implicit (i.e., automatic) and explicit (i.e., voluntary) subprocesses. The Emotional Control scale from the Behavior Rating Inventory of Executive Function was used to evaluate emotional control in daily life, and WM organization was assessed with diffusion tensor imaging. Results: We found that emotional faces captured attention across all groups (F(1,51) = 32.18, p < .001, η2p = .39). However, unlike typically developing children, patients were unable to override the attentional capture of emotional faces when instructed to (emotional face-by-group interaction: F(2,51) = 5.58, p = .006, η2p = .18). Across all children, our eye-tracking measure of emotion regulation was modestly associated with the parent-report emotional control score (r = .29, p = .045), and in patients it was associated with WM microstructure in the body and splenium of the corpus callosum (all t > 3.03, all p < .05). Conclusions: Our findings suggest that an attention-related component process of emotion regulation is disrupted in children treated for brain tumors, and that it may relate to their emotional difficulties and WM organization. This work provides a foundation for future theoretical and mechanistic investigations of emotional difficulties in brain tumor survivors.

INTRODUCTION Treatments for pediatric brain tumors (PBT) are neurotoxic and lead to long-term deficits that are driven by the perturbation of underlying white matter (WM). It is unclear if and how treatment may impair WM connectivity across the entire brain. METHODS Magnetic resonance images from 41 PBT survivors (mean age: 13.19 years, 53% M) and 41 typically developing (TD) children (mean age: 13.32 years, 51% M) were analyzed. Image reconstruction, segmentation, and node parcellation were completed in FreeSurfer. DTI maps and probabilistic streamline generation were completed in MRtrix3. Connectivity matrices were based on the number of streamlines connecting two nodes and the mean DTI (FA) index across streamlines. We used graph theoretical analyses to define structural differences between groups, and random forest (RF) analyses to identify hubs that reliably classify PBT and TD children. RESULTS For survivors treated with radiation, betweeness centrality was greater in the left insular (p &lt; 0.000) but smaller in the right pallidum (p &lt; 0.05). For survivors treated without radiation (surgery-only), betweeness centrality was smaller in the right interparietal sulcus (p &lt; 0.05). RF analyses showed that differences in WM connectivity from the right pallidum to other parts of the brain reliably classified PBT survivors from TD children (classification accuracy = 77%). CONCLUSIONS The left insular, right pallidum, and right inter-parietal sulcus are structurally perturbed hubs in PBT survivors. WM connectivity from the right pallidum is vulnerable to the long-term effects of treatment for PBT.

Background Pediatric brain tumor (PBT) survivors are at an increased risk for white matter (WM) injury. However, damage to whole-brain structural connectivity is unelucidated. The impact of treatment on WM connectivity was investigated. Methods Whole-brain WM networks were derived from diffusion tensor imaging data acquired for twenty-eight irradiated patients (RT) (mean age = 13.74 ±3.32 years), thirteen patients not irradiated (No RT) (mean age = 12.57 ±2.87), and forty-one typically developing children (TDC) (mean age = 13.32 ±2.92 years). Differences in network properties were analyzed using robust regressions. Results Participation coefficient was lower in both patient groups (RT: adj.p = 0.015; No RT: adj.p = 0.042). Compared to TDC, RT had greater clustering (adj.p = 0.015), local efficiency (adj.p = 0.003), and modularity (adj.p = 0.000003). WM traced from hubs was damaged in patients: left hemisphere pericallosal sulcus (FA [F = 4.97; q &lt; 0.01]; MD [F = 11.02; q &lt; 0.0001]; AD [F = 10.00; q &lt; 0.0001]; RD [F = 8.53; q &lt; 0.0001]), right hemisphere pericallosal sulcus (FA [F = 8.87; q &lt; 0.0001 ]; RD [F = 8.27; q &lt; 0.001]), and right hemisphere parietooccipital sulcus (MD [F = 5.78; q &lt; 0.05]; RD [F = 5.12; q &lt; 0.05]).​ Conclusions Findings indicate greater segregation of WM networks after RT. Intermodular connectivity was lower after treatment with and without RT. No significant network differences were observed between patient groups. Our results are discussed in the context of a network approach that emphasizes interactions between brain regions.