White matter microstructural abnormality in children with hydrocephalus detected by probabilistic diffusion tractography

BACKGROUND AND PURPOSE

Hydrocephalus is a severe pathologic condition in which WM damage is a major factor associated with poor outcomes. The goal of the study was to investigate tract-based WM connectivity and DTI measurements in children with hydrocephalus by using the probabilistic diffusion tractography method.

MATERIALS AND METHODS

Twelve children with hydrocephalus and 16 age-matched controls were included in the study. Probabilistic diffusion tractography was conducted to generate tract-based connectivity distribution and DTI measures for the genu of the corpus callosum and the connectivity index. Tract-based summary measurements, including the connectivity index and DTI measures (fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity), were calculated and compared between the 2 study groups.

RESULTS

Tract-based summary measurement showed a higher percentage of voxels with lower normalized connectivity index values in the WM tracts in children with hydrocephalus. In the genu of the corpus callosum, the left midsegment of the corticospinal tract, and the right midsegment of the corticospinal tract, the normalized connectivity index value in children with hydrocephalus was found to be significantly lower (P < .05, corrected). The tract-based DTI measures showed that the children with hydrocephalus had significantly higher mean diffusivity, axial diffusivity, and radial diffusivity in the genu of the corpus callosum, left midsegment of the corticospinal tract, and right midsegment of corticospinal tract and lower fractional anisotropy in the genu of the corpus callosum (P < .05, corrected).

CONCLUSIONS

The analysis of WM connectivity showed that the probabilistic diffusion tractography method is a sensitive tool to detect the decreased continuity in WM tracts that are under the direct influence of mechanical distortion and increased intracranial pressure in hydrocephalus. This voxel-based connectivity method can provide quantitative information complementary to the standard DTI summary measures.

Age at stroke determines post-stroke language lateralization

PURPOSE

To determine how age at the time of left middle cerebral artery stroke affects language lateralization in a combined sample of subjects with perinatal, childhood, and adult stroke.

METHODS

19 participants who had perinatal stroke (<1 month of age), 32 with later stroke, and 51 sex-/age-matched healthy controls (HCs) received fMRI of language using verb generation task (VGT).

RESULTS

Percent lesion volumes were not different between groups (perinatal vs. late stroke) when taking brain volume into account (p = 0.084). Perinatal stroke group showed bilateral signal increases compared to more left-lateralized signals in matched HCs; late stroke group and HCs both showed left-hemispheric signal increases. LIs in the stroke groups were consistently more bilateral than in HCs (all p < 0.008) except for the late group's posterior LI (p = 0.080). There was greater proportion of leftward language lateralization in HCs compared to their respective stroke groups (78.9% vs. 31.6% in perinatal; 87.5% vs. 59.4% in late stroke; p = 0.004) and a larger proportion of leftward lateralization in late compared to perinatal stroke (p = 0.039). The age of stroke occurrence showed significant positive associations with global and frontal LI (both p ≤ 0.007).

CONCLUSION

As expected, the age of stroke occurrence affects subsequent verb generation lateralization. Greater cortical plasticity is observed in earlier stroke while later stroke is associated with reliance on the repair of the previously damaged left-hemispheric networks.

Obese adolescents with type 2 diabetes perform worse than controls on cognitive and behavioral assessments

BACKGROUND

Children with type 1 diabetes demonstrate worse cognitive performance compared with their peers. Little is known regarding the cognitive and behavioral performance in obese adolescents with type 2 diabetes.

METHODS

Cross sectional evaluation of 20 obese adolescents with type 2 diabetes and 20 healthy adolescents was performed in Cincinnati, Ohio. Cognitive tests that included measures of processing speed, working memory, verbal and semantic fluency and parent reports of executive function and problem behavior were compared. Academic achievement and the relationship between cognitive/behavioral scores and diabetes duration and diabetes control (hemoglobin A1c) were assessed in the type 2 diabetes group only.

RESULTS

The type 2 diabetes group had mean duration of diabetes of 2.8 ± 2.2 yr and hemoglobin A1c of 7.9 ± 2.2%. Adolescents with type 2 diabetes scored lower than controls on tests of working and verbal memory and processing speed (all p < 0.05) and worse for Internalizing, Externalizing, and Total Problems behaviors on the Child Behavior Checklist (all p < 0.05). Adolescents with type 2 diabetes scored below the population mean in academic achievement, most notably calculation. Working memory and processing speed were negatively correlated with duration of diabetes (r = -0.50 and -0.47, respectively, p < 0.05).

CONCLUSIONS

Obese youth with type 2 diabetes score poorly compared with controls on multiple assessments of cognitive function and adaptive behavior. Further work is needed to determine if these effects are driven by obesity, diabetes or other demographic and socioeconomic risk factors.

Extremely preterm children exhibit increased interhemispheric connectivity for language: findings from fMRI-constrained MEG analysis

Children born extremely preterm are at significant risk for cognitive impairment, including language deficits. The relationship between preterm birth and neurological changes that underlie cognitive deficits is poorly understood. We use a stories-listening task in fMRI and MEG to characterize language network representation and connectivity in children born extremely preterm (n = 15, <28 weeks gestation, ages 4-6 years), and in a group of typically developing control participants (n = 15, term birth, 4-6 years). Participants completed a brief neuropsychological assessment. Conventional fMRI analyses revealed no significant differences in language network representation across groups (p > .05, corrected). The whole-group fMRI activation map was parcellated to define the language network as a set of discrete nodes, and the timecourse of neuronal activity at each position was estimated using linearly constrained minimum variance beamformer in MEG. Virtual timecourses were subjected to connectivity and network-based analyses. We observed significantly increased beta-band functional connectivity in extremely preterm compared to controls (p < .05). Specifically, we observed an increase in connectivity between left and right perisylvian cortex. Subsequent effective connectivity analyses revealed that hyperconnectivity in preterms was due to significantly increased information flux originating from the right hemisphere (p < 0.05). The total strength and density of the language network were not related to language or nonverbal performance, suggesting that the observed hyperconnectivity is a "pure" effect of prematurity. Although our extremely preterm children exhibited typical language network architecture, we observed significantly altered network dynamics, indicating reliance on an alternative neural strategy for the language task.

A linear structural equation model for covert verb generation based on independent component analysis of FMRI data from children and adolescents

Human language is a complex and protean cognitive ability. Young children, following well defined developmental patterns learn language rapidly and effortlessly producing full sentences by the age of 3 years. However, the language circuitry continues to undergo significant neuroplastic changes extending well into teenage years. Evidence suggests that the developing brain adheres to two rudimentary principles of functional organization: functional integration and functional specialization. At a neurobiological level, this distinction can be identified with progressive specialization or focalization reflecting consolidation and synaptic reinforcement of a network (Lenneberg, 1967; Muller et al., 1998; Berl et al., 2006). In this paper, we used group independent component analysis and linear structural equation modeling (McIntosh and Gonzalez-Lima, 1994; Karunanayaka et al., 2007) to tease out the developmental trajectories of the language circuitry based on fMRI data from 336 children ages 5–18 years performing a blocked, covert verb generation task. The results are analyzed and presented in the framework of theoretical models for neurocognitive brain development. This study highlights the advantages of combining both modular and connectionist approaches to cognitive functions; from a methodological perspective, it demonstrates the feasibility of combining data-driven and hypothesis driven techniques to investigate the developmental shifts in the semantic network.

Characterizing Information Flux Within the Distributed Pediatric Expressive Language Network: A Core Region Mapped Through fMRI-Constrained MEG Effective Connectivity Analyses

Using noninvasive neuroimaging, researchers have shown that young children have bilateral and diffuse language networks, which become increasingly left lateralized and focal with development. Connectivity within the distributed pediatric language network has been minimally studied, and conventional neuroimaging approaches do not distinguish task-related signal changes from those that are task essential. In this study, we propose a novel multimodal method to map core language sites from patterns of information flux. We retrospectively analyze neuroimaging data collected in two groups of children, ages 5–18 years, performing verb generation in functional magnetic resonance imaging (fMRI) (n = 343) and magnetoencephalography (MEG) (n = 21). The fMRI data were conventionally analyzed and the group activation map parcellated to define node locations. Neuronal activity at each node was estimated from MEG data using a linearly constrained minimum variance beamformer, and effective connectivity within canonical frequency bands was computed using the phase slope index metric. We observed significant (p ≤ 0.05) effective connections in all subjects. The number of suprathreshold connections was significantly and linearly correlated with participant's age (r = 0.50, n = 21, p ≤ 0.05), suggesting that core language sites emerge as part of the normal developmental trajectory. Across frequencies, we observed significant effective connectivity among proximal left frontal nodes. Within the low frequency bands, information flux was rostrally directed within a focal, left frontal region, approximating Broca's area. At higher frequencies, we observed increased connectivity involving bilateral perisylvian nodes. Frequency-specific differences in patterns of information flux were resolved through fast (i.e., MEG) neuroimaging.

Altered white matter microstructure underlies listening difficulties in children suspected of auditory processing disorders: a DTI study

INTRODUCTION

The purpose of the present study was to identify biomarkers of listening difficulties by investigating white matter microstructure in children suspected of auditory processing disorder (APD) using diffusion tensor imaging (DTI). Behavioral studies have suggested that impaired cognitive and/or attention abilities rather than a pure sensory processing deficit underlie listening difficulties and auditory processing disorder (APD) in children. However, the neural signature of listening difficulties has not been investigated.

METHODS

Twelve children with listening difficulties and atypical left ear advantage (LEA) in dichotic listening and twelve age- and gender-matched typically developing children with typical right ear advantage (REA) were tested. Using voxel-based analysis, fractional anisotropy (FA), and mean, axial and radial diffusivity (MD, AD, RD) maps were computed and contrasted between the groups.

RESULTS

Listening difficulties were associated with altered white matter microstructure, reflected by decreased FA in frontal multifocal white matter regions centered in prefrontal cortex bilaterally and left anterior cingulate. Increased RD and decreased AD accounted for the decreased FA, suggesting delayed myelination in frontal white matter tracts and disrupted fiber organization in the LEA group. Furthermore, listening difficulties were associated with increased MD (with increase in both RD and AD) in the posterior limb of the internal capsule (sublenticular part) at the auditory radiations where auditory input is transmitted between the thalamus and the auditory cortex.

CONCLUSIONS

Our results provide direct evidence that listening difficulties in children are associated with altered white matter microstructure and that both sensory and supramodal deficits underlie the differences between the groups.

Multiple sclerosis: pathogenesis and MR imaging features of T1 hypointensities in a [corrected] murine model

PURPOSE

To prospectively determine how T1 hypointensities (T1 black holes) on brain magnetic resonance (MR) images are generated by the immune system by using a Theiler murine encephalitis virus-induced model of multiple sclerosis and high-field-strength MR imaging.

MATERIALS AND METHODS

All animal protocols and experiments were approved by the institutional animal care and use committee. Volumetric MR imaging studies were conducted at 7 T in six C57BL/6 mice and in immune differentiation marker (recombination activation gene [RAG]-1)-, immune cell (CD4, CD8)-, and immune effector molecule (Fas ligand, perforin)-deficient mice (six mice in each group) to determine which immune cell types and effector molecules lead to T1 hypointensities. The main outcome measure was the total T1 black hole volume per animal, as determined with volumetric analysis, and was analyzed statistically by using software.

RESULTS

Compared with C57BL/6 mice, RAG-1-deficient mice showed a significant (P = .003) decrease in total T1 black hole volume, suggesting a clear role for the adaptive immune system. While CD4-deficient mice did not show a significant decrease in T1 black hole volume (P = .33), CD8-deficient mice did (P = .003). Perforin-deficient mice showed a significant reduction of T1 black hole volume (P = .002), whereas Fas ligand-deficient mice did not (P = .77).

CONCLUSION

The data suggest that CD8 T cells utilizing perforin effector molecules are responsible for T1 black hole formation.

Success rates for functional MR imaging in children

BACKGROUND AND PURPOSE

Functional MR imaging is widely used for research in functional brain development in healthy children. However, obtaining high-quality brain imaging data from pediatric research participants requires cooperation that is challenging for young children. In this study, we examined success rates for fMRI in typically developing children in both longitudinal and cross-sectional research study designs to inform the recruitment needs of future pediatric brain imaging studies.

MATERIALS AND METHODS

In the cross-sectional study, 459 healthy children (5-18 years of age, 215 girls) were recruited. A subset of 30 healthy children 5-7 years of age from the cross-sectional cohort were selected and scanned for 10 consecutive years in the longitudinal arm of the study. Following anatomic scans, each participant attempted 4 functional MR imaging tasks. Success rate was defined as the proportion of fMRI tasks completed. Differences in success rates across sexes and in cross-sectional-versus-longitudinal cohorts were evaluated by using the Fischer exact test.

RESULTS

In the cross-sectional study, 74% of the children completed all tasks. Success rates for individual tasks ranged from 34% to 67% for children 5-7 years of age and 76%-100% for those 8-18 years of age. In the longitudinal study, 89% of children completed all tasks in all 10 years. We established significance (P < .0001) between the cross-sectional and longitudinal cohorts for both 0% and 100% task completion rates. There was no significance between sexes.

CONCLUSIONS

When designing pediatric fMRI studies in children, the sample sizes indicated by power analysis should be scaled up according to age (ie, 33% for ages 8-18 years, 50% for ages 5-7 years).

Longitudinal fMRI study of language recovery after a left hemispheric ischemic stroke

BACKGROUND

Recovery from stroke-induced aphasia is typically protracted and involves complex functional reorganization. The relative contributions of the lesioned and non-lesioned hemispheres to this process have been examined in several cross-sectional studies but longitudinal studies involving several time-points and large numbers of subjects are scarce.

OBJECTIVE

The aim of this study was to address the gaps in the literature by longitudinally studying the evolution of post-stroke lateralization and localization of language-related fMRI activation in the first year after single left hemispheric ischemic stroke.

METHOD

Seventeen patients with stroke-induced aphasia were enrolled to undergo detailed behavioral testing and fMRI at 2, 6, 12, 26, and 52 weeks post-stroke. Matched for age, handedness and sex participants were also enrolled to visualize canonical language regions.

RESULTS

Behavioral results showed improvements over time for all but one of the behavioral scores (Semantic Fluency Test). FMRI results showed that the left temporal area participates in compensation for language deficits in the first year after stroke, that there is a correlation between behavioral improvement and the left cerebellar activation over time, and that there is a shift towards stronger frontal left-lateralization of the fMRI activation over the first year post-stroke. Temporary compensation observed in the initial phases of post-stroke recovery that involves the non-lesioned hemisphere may not be as important as previously postulated, since in this study the recovery was driven by activations in the left fronto-temporal regions.

CONCLUSION

Language recovery after left hemispheric ischemic stroke is likely driven by the previously involved in language and attention left hemispheric networks.

Structure and order of the protein and carbohydrate domains of prothrombin fragment 1

The three-dimensional structure of prothrombin fragment 1 has been determined by X-ray crystallography at 3.8 A resolution. The fragment is composed of a number of structural units, some of which are ordered while others are disordered. The ordered part of the structure includes a compact kringle unit, a helical domain and a carbohydrate chain. The kringle structure is organized around a close pair of buried disulfide bridges. One of its carbohydrate chains, that attached to Asn 101, is fully ordered, but the carbohydrate chain attached to Asn 77 appears to be disordered. The calcium binding unit is composed of a disordered part containing all ten gamma-carboxyglutamic acid residues and an ordered part forming the helical domain. The highly conserved residues Phe 41, Trp 42 and Tyr 45, which form a hydrophobic cluster on the first helix, interact around a crystallographic two-fold axis with the equivalent residues in another molecule to form a dimer in the crystal.

Reprint of "Cortical reorganization of language functioning following perinatal left MCA stroke" [Brain and Language 105 (2008) 99-111]

OBJECTIVE

Functional MRI was used to determine differences in patterns of cortical activation between children who suffered perinatal left middle cerebral artery (MCA) stroke and healthy children performing a silent verb generation task.

METHODS

Ten children with prior perinatal left MCA stroke (age 6-16 years) and ten healthy age matched controls completed an executive language activation task. fMRI scans were acquired on a 3T scanner using T2* weighted gradient echo, echo-planar imaging (EPI) sequence. Random effects analysis and independent component analysis (ICA) were used to compute activation maps.

RESULTS

Both analysis methods demonstrated alternative activation of cortical areas in children with perinatal stroke. Following perinatal stroke, typical left dominant productive language areas in the inferior frontal gyrus were displaced to anatomical identical areas in the right hemisphere (p=.001). In addition, stroke patients showed more bilateral activation in superior temporal and anterior cingulate gyri and increased activation in primary visual cortex when compared to healthy controls. There was no relation between lesion size and the degree of right hemisphere activation. ICA showed that the healthy controls had a negative correlation with the time course in the right inferior frontal gyrus in the same region that was activated in stroke subjects.

INTERPRETATION

This functional MRI study in children revealed novel patterns of cortical language reorganization following perinatal stroke. The addition of ICA is complementary to Random Effects Analysis, allowing for the exploration of potential subtle differences in pathways in functional MRI data obtained from both healthy and pathological groups.

19F NMR monitoring of in vivo tumor metabolism after biochemical modulation of 5-fluorouracil by the uridine phosphorylase inhibitor 5-benzylacyclouridine

A uridine phosphorylase inhibitor, 5-benzylacyclouridine (BAU), has been utilized as biochemical modulator of 5-fluorouracil (5-FU) anti-tumor activity in a murine tumor model. The effect of BAU on 5-FU metabolism has been evaluated using in vitro and in vivo 19F NMR spectroscopy. The analysis of the NMR data revealed an increased formation and retention of fluorouracil nucleotides and fluorouridine in colon 38 tumors treated with the regimen containing BAU and a reduction in 5-FU catabolites (alpha-fluoro-beta-ureidopropionic acid and alpha-fluoro-beta-alanine). In the normal tissues evaluated, the presence of BAU did not significantly alter the metabolism and presence of fluoropyrimidine species, indicating a more selective effect on tumor tissues. Therapy experiments on C57/BL6 mice bearing colon 38 tumor showed that the administration of 120 mg/kg BAU 30 min before 5-FU at 85 mg/kg, on a weekly basis, resulted in an increased antineoplastic effect compared to the same dose of 5-FU alone. A smaller dose of 5-FU (60 mg/kg) also administered 30 min after 120 mg/kg BAU caused a reduction in tumor growth similar to 5-FU alone. The addition of BAU to 5-FU (85 mg/kg) resulted in a slight increase, although statistically nonsignificant, in host toxicity without causing any toxic death during the chemotherapeutic treatment. 19F NMR spectroscopy is here shown to be a powerful technique to evaluate changes in the metabolism of fluoropyrimidines after the use of biochemical modulator and to allow a correlation between improved therapeutic response with the biochemical effects generated in tissues.

Compensatory brain activation for recognition memory in patients with medication-resistant epilepsy

Progressive decline of memory functions has been observed in patients with chronic medication-resistant epilepsy. The progression likely relates to the effects of epileptiform discharges, seizures, and medications on the processes of encoding and retrieval. The goal of the study described here was to use functional MRI (fMRI) to examine the effects of chronic epilepsy on verbal recognition memory. We enrolled 12 patients with medication-resistant epilepsy (5 with right and 7 with left hemispheric seizure onset) and 18 healthy controls matched for age, gender, and handedness. Subjects underwent fMRI at 3T using a word recognition task during which they had to recall if words presented during scanning were words they had learned prior to scanning. Although we noted many similarities in the fMRI activation patterns between the subjects with epilepsy and the healthy subjects in areas typically involved in memory processing, testing of the interaction effects for target-foil differences between groups revealed several differences in activation including the right insula, the left cuneus, and the bilateral subgenual anterior cingulate cortex (ACC). In patients with epilepsy, these regions exhibited greater activation for targets than foils, but in healthy subjects the difference was reversed (right insula), absent (left cuneus), or included deactivation to target words (pregenual ACC). These differences were seen despite similar performance during the memory task, suggesting that activations observed in these additional regions may represent compensatory processes for verbal recognition memory that are induced by chronic brain injury related to recurrent seizures.

Behavioral and emotional dysregulation trajectories marked by prefrontal-amygdala function in symptomatic youth

BACKGROUND

Neuroimaging measures of behavioral and emotional dysregulation can yield biomarkers denoting developmental trajectories of psychiatric pathology in youth. We aimed to identify functional abnormalities in emotion regulation (ER) neural circuitry associated with different behavioral and emotional dysregulation trajectories using latent class growth analysis (LCGA) and neuroimaging.

METHOD

A total of 61 youth (9-17 years) from the Longitudinal Assessment of Manic Symptoms study, and 24 healthy control youth, completed an emotional face n-back ER task during scanning. LCGA was performed on 12 biannual reports completed over 5 years of the Parent General Behavior Inventory 10-Item Mania Scale (PGBI-10M), a parental report of the child's difficulty regulating positive mood and energy.

RESULTS

There were two latent classes of PGBI-10M trajectories: high and decreasing (HighD; n=22) and low and decreasing (LowD; n=39) course of behavioral and emotional dysregulation over the 12 time points. Task performance was >89% in all youth, but more accurate in healthy controls and LowD versus HighD (p<0.001). During ER, LowD had greater activity than HighD and healthy controls in the dorsolateral prefrontal cortex, a key ER region, and greater functional connectivity than HighD between the amygdala and ventrolateral prefrontal cortex (p's<0.001, corrected).

CONCLUSIONS

Patterns of function in lateral prefrontal cortical-amygdala circuitry in youth denote the severity of the developmental trajectory of behavioral and emotional dysregulation over time, and may be biological targets to guide differential treatment and novel treatment development for different levels of behavioral and emotional dysregulation in youth.

Diffusion tensor imaging of white matter injury in a rat model of infantile hydrocephalus

OBJECTIVE

Diffusion tensor imaging (DTI) is a non-invasive MRI technique that has been used to quantify white matter (WM) abnormality in both clinical and experimental hydrocephalus (HCP). However, no DTI study has been conducted to characterize anisotropic diffusion properties in an animal model of infantile HCP. This DTI study was designed to investigate a rat model of HCP induced at postnatal day 21, a time developmentally equivalent to the human infancy.

METHODS

DTI data were acquired at approximately 4 weeks after the induction of HCP with kaolin injection. Using a 7 Tesla small animal MRI scanner we performed high-resolution DTI on 12 rats with HCP and 6 saline controls. Regions of interest (ROI) examined with quantitative comparisons include the genu, body, and splenium of the corpus callosum (gCC, bCC, and sCC, respectively), anterior, middle, and posterior external capsule (aEC, mEC, and pEC, respectively), internal capsule (IC), and fornix (FX). For each ROI, DTI metrics including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Dax), and radial diffusivity (Drad) were calculated.

RESULTS

We found that the anisotropic diffusion properties were abnormal across multiple WM regions in the brains of the HCP rats. Statistically significant differences included: (1) decreased FA and increased MD and Drad values in the gCC and bCC; (2) increased Dax in the sCC; (3) increased FA and Dax in the aEC; (4) increased FA in the mEC; (5) increased MD and Drad in the pEC; (6) increased FA and Dax in IC; (7) increased FA in FX.

CONCLUSIONS

These preliminary results provide the first evidence of WM injury quantified by DTI in a rat model of infantile HCP. Our data showed that DTI is a sensitive tool to characterize patterns of WM abnormalities and support the notion that WM impairment is region specific in response to HCP.

Concordance of MEG and fMRI patterns in adolescents during verb generation

In this study we focused on direct comparison between the spatial distributions of activation detected by functional magnetic resonance imaging (fMRI) and localization of sources detected by magnetoencephalography (MEG) during identical language tasks. We examined the spatial concordance between MEG and fMRI results in 16 adolescents performing a three-phase verb generation task that involves repeating the auditorily presented concrete noun and generating verbs either overtly or covertly in response to the auditorily presented noun. MEG analysis was completed using a synthetic aperture magnetometry (SAM) technique, while the fMRI data were analyzed using the general linear model approach with random-effects. To quantify the agreement between the two modalities, we implemented voxel-wise concordance correlation coefficient (CCC) and identified the left inferior frontal gyrus and the bilateral motor cortex with high CCC values. At the group level, MEG and fMRI data showed spatial convergence in the left inferior frontal gyrus for covert or overt generation versus overt repetition, and the bilateral motor cortex when overt generation versus covert generation. These findings demonstrate the utility of the CCC as a quantitative measure of spatial convergence between two neuroimaging techniques.

Extremely preterm children exhibit altered cortical thickness in language areas

Children born extremely preterm (< 28 weeks gestation, EPT) are at increased risk for language and other neurocognitive deficits compared to term controls (TC). Prior studies have reported both increases and decreases in cortical thickness in EPT across the cerebrum. These studies have not formally normalized for intracranial volume (ICV), which is especially important as EPT children often have smaller stature, head size, and ICV. We previously reported increased interhemispheric functional and structural connectivity in a well-controlled group of school-aged EPT children with no known brain injury or neurological deficits. Functional and structural hyperconnectivity between left and right temporoparietal regions was positively related with language scores in EPT, which may be reflected in measures of cortical thickness. To characterize possible language network cortical thickness effects, 15 EPT children and 15 TC underwent standardized assessments of language and structural magnetic resonance imaging at 4 to 6 years of age. Images were subjected to volumetric and cortical thickness analyses using FreeSurfer. Whole-brain analyses of cortical thickness were conducted both with and without normalization by ICV. Non-normalized results showed thinner temporal cortex for EPT, while ICV-normalized results showed thicker cortical regions in the right temporal lobe (FDRq = 0.05). Only ICV-normalized results were significantly related to language scores, with right temporal cortical thickness being positively correlated with performance.

Neural correlates of risky decision making in adolescents with and without traumatic brain injury using the balloon analog risk task

We studied risky decision making (RDM) in 8 healthy adolescents (TC) and 11 adolescents with mild to moderate traumatic brain injuries (TBI) using the Balloon Analog Risk Task (BART) and functional magnetic resonance imaging (fMRI). Participants inflated simulated balloons (with more points awarded to bigger balloons), which might burst at any time. Increasing brain activation levels were associated with increasing balloon size in a largely bilateral network, including cerebellar, inferior parietal, limbic, and frontal areas. Both groups performed similarly and activated similar networks.

Functional magnetic resonance imaging of story listening in adolescents and young adults with Down syndrome: evidence for atypical neurodevelopment

BACKGROUND

Previous studies have documented differences in neural activation during language processing in individuals with Down syndrome (DS) in comparison with typically developing individuals matched for chronological age. This study used functional magnetic resonance imaging (fMRI) to compare activation during language processing in young adults with DS to typically developing comparison groups matched for chronological age or mental age. We hypothesised that the pattern of neural activation in the DS cohort would differ when compared with both typically developing cohorts.

METHOD

Eleven persons with DS (mean chronological age = 18.3; developmental age range = 4-6 years) and two groups of typically developing individuals matched for chronological (n = 13; mean age = 18.3 years) and developmental (mental) age (n = 12; chronological age range = 4-6 years) completed fMRI scanning during a passive story listening paradigm. Random effects group comparisons were conducted on individual maps of the contrast between activation (story listening) and rest (tone presentation) conditions.

RESULTS

Robust activation was seen in typically developing groups in regions associated with processing auditory information, including bilateral superior and middle temporal lobe gyri. In contrast, the DS cohort demonstrated atypical spatial distribution of activation in midline frontal and posterior cingulate regions when compared with both typically developing control groups. Random effects group analyses documented reduced magnitude of activation in the DS cohort when compared with both control groups.

CONCLUSIONS

Activation in the DS group differed significantly in magnitude and spatial extent when compared with chronological and mental age-matched typically developing control groups during a story listening task. Results provide additional support for an atypical pattern of functional organisation for language processing in this population.

Reading improvement in English- and Hebrew-speaking children with reading difficulties after reading acceleration training

A reading acceleration program known to improve reading fluency in Hebrew-speaking adults was tested for its effect on children. Eighty-nine Hebrew- and English-speaking children with reading difficulties were divided into a waiting list group and two training groups (Hebrew and English) and underwent 4 weeks of reading acceleration training. Results of pre- and post-testing of reading abilities point to a significant main effect of the test, demonstrating improvements in silent contextual reading speed, reading comprehension, and speed of processing in both Hebrew and English training groups as compared to their performance before the intervention. This study indicates that the Reading Acceleration Program might be an effective program for improving reading abilities in children, independent of language.

Reward-related neural activity and structure predict future substance use in dysregulated youth

BACKGROUND

Identifying youth who may engage in future substance use could facilitate early identification of substance use disorder vulnerability. We aimed to identify biomarkers that predicted future substance use in psychiatrically un-well youth.

METHOD

LASSO regression for variable selection was used to predict substance use 24.3 months after neuroimaging assessment in 73 behaviorally and emotionally dysregulated youth aged 13.9 (s.d. = 2.0) years, 30 female, from three clinical sites in the Longitudinal Assessment of Manic Symptoms (LAMS) study. Predictor variables included neural activity during a reward task, cortical thickness, and clinical and demographic variables.

RESULTS

Future substance use was associated with higher left middle prefrontal cortex activity, lower left ventral anterior insula activity, thicker caudal anterior cingulate cortex, higher depression and lower mania scores, not using antipsychotic medication, more parental stress, older age. This combination of variables explained 60.4% of the variance in future substance use, and accurately classified 83.6%.

CONCLUSIONS

These variables explained a large proportion of the variance, were useful classifiers of future substance use, and showed the value of combining multiple domains to provide a comprehensive understanding of substance use development. This may be a step toward identifying neural measures that can identify future substance use disorder risk, and act as targets for therapeutic interventions.

Deriving the generic structure of the fibronectin type II domain from the prothrombin Kringle 1 crystal structure

The proposed homology between the fibronectin type II domain and the Kringle domains of blood clotting and fibrinolytic proteins has been examined in three dimensions by substituting the type II sequence into the bovine prothrombin Kringle 1 tertiary structure, determined by X-ray crystallographical methods at 3.8 A. Structural substitution of aligned amino acids of the type II domains and the Kringle produces a compact chain fold and deletions and insertions in the type II sequence are accommodated within the modelled structure. This confirms the structural homology between the two domains and verifies the sequence alignment and common evolution of the type II and Kringle units. The two structures contain homologous hydrophobic cores, centered around the two disulphide bridges which link conserved beta-type strands. Gross differences between the two domains occur in exterior loops and potential functional sites in these regions of the type II structures as found in fibronectin, Factor XII and seminal fluid protein PDC-109 are proposed. We suggest that the domains evolved from a common ancestral protein comprising the hydrophobic core and disulphide arrangement which later diverged to bind different macromolecules through adaptation of the external loops.

Rewiring the extremely preterm brain: Altered structural connectivity relates to language function

Children born preterm are at increased risk for cognitive impairment, with higher-order functions such as language being especially vulnerable. Previously, we and others have reported increased interhemispheric functional connectivity in children born extremely preterm; the finding appears at odds with literature showing decreased integrity of the corpus callosum, the primary commissural bundle, in preterm children. We address the apparent discrepancy by obtaining advanced measures of structural connectivity in twelve school-aged children born extremely preterm (<28 weeks) and ten term controls. We hypothesize increased extracallosal structural connectivity might support the functional hyperconnectivity we had previously observed. Participants were aged four to six years at time of study and groups did not differ in age, sex, race, ethnicity, or socioeconomic status. Whole-brain and language-network-specific (functionally-constrained) connectometry analyses were performed. At the whole-brain level, preterm children had decreased connectivity in the corpus callosum and increased connectivity in the cerebellum versus controls. Functionally-constrained analyses revealed significantly increased extracallosal connectivity between bilateral temporal regions in preterm children (FDRq <0.05). Connectivity within these extracallosal pathways was positively correlated with performance on standardized language assessments in children born preterm (FDRq <0.001), but unrelated to performance in controls. This is the first study to identify anatomical substrates for increased interhemispheric functional connectivity in children born preterm; increased reliance on an extracallosal pathway may represent a biomarker for resiliency following extremely preterm birth.