scholarly journals A model of tension-induced fiber growth predicts white matter organization during brain folding

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kara E. Garcia ◽  
Xiaojie Wang ◽  
Christopher D. Kroenke
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Ex Vivo ◽  
Brain Connectivity ◽  
Cortical Folding ◽  
Fiber Growth ◽  
Biomechanical Models ◽  
Induced Folding ◽  
Model Predictions ◽  
Fiber Organization

AbstractThe past decade has experienced renewed interest in the physical processes that fold the developing cerebral cortex. Biomechanical models and experiments suggest that growth of the cortex, outpacing growth of underlying subcortical tissue (prospective white matter), is sufficient to induce folding. However, current models do not explain the well-established links between white matter organization and fold morphology, nor do they consider subcortical remodeling that occurs during the period of folding. Here we propose a framework by which cortical folding may induce subcortical fiber growth and organization. Simulations incorporating stress-induced fiber elongation indicate that subcortical stresses resulting from folding are sufficient to induce stereotyped fiber organization beneath gyri and sulci. Model predictions are supported by high-resolution ex vivo diffusion tensor imaging of the developing rhesus macaque brain. Together, results provide support for the theory of cortical growth-induced folding and indicate that mechanical feedback plays a significant role in brain connectivity.

scholarly journals A model of tension-induced fiber growth predicts white matter organization during brain folding

2020 ◽  
Author(s):  
Kara Garcia ◽  
Xiaojie Wang ◽  
Christopher Kroenke
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Ex Vivo ◽  
Brain Connectivity ◽  
Cortical Folding ◽  
Fiber Growth ◽  
Biomechanical Models ◽  
Induced Folding ◽  
Model Predictions ◽  
Fiber Organization

Abstract The past decade has experienced renewed interest in the physical processes that fold the developing cerebral cortex. Biomechanical models and experiments suggest that growth of the cortex, outpacing growth of underlying subcortical tissue (prospective white matter), is sufficient to induce folding. However, current models do not explain the well-established links between white matter organization and fold morphology, nor do they consider dramatic subcortical remodeling that occurs during the period of folding. This study proposes a novel paradigm in which cortical folding induces subcortical fiber growth and organization. Simulations incorporating stress-induced fiber growth indicate that subcortical stresses resulting from folding are sufficient to induce stereotyped fiber organization beneath gyri and sulci. Model predictions are supported by high-resolution ex vivo diffusion tensor imaging of the developing rhesus macaque brain. Results provide support for the theory of cortical growth-induced folding and indicate that mechanical feedback plays a significant role in brain connectivity.

scholarly journals Acute ex vivo changes in brain white matter diffusion tensor metrics

PLoS ONE ◽  
2019 ◽  
Vol 14 (9) ◽  
pp. e0223211
Author(s):  
Matthew R. Walker ◽  
Jidan Zhong ◽  
Adam C. Waspe ◽  
Thomas Looi ◽  
Karolina Piorkowska ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Ex Vivo ◽  
Brain White Matter

scholarly journals 0086 Daytime Napping and Memory Consolidation of Novel Word Learning in Children and Adults

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A35-A35
Author(s):  
E van Rijn ◽  
S A Walker ◽  
V C Knowland ◽  
S A Cairney ◽  
A D Gouws ◽  
...  
Keyword(s):  
White Matter ◽  
Memory Consolidation ◽  
Slow Wave Sleep ◽  
Diffusion Tensor ◽  
Brain Connectivity ◽  
Nrem Sleep ◽  
Sleep Spindles ◽  
Adults And Children ◽  
Structural Brain ◽  
Novel Words

Abstract Introduction Memory for novel words benefits from sleep, particularly non-rapid eye movement (NREM) sleep and its features, such as sleep spindles and slow oscillations. This is consistent with systems consolidation models, in which sleep supports transfer from hippocampal to neocortical memory networks. Larger amounts of slow wave sleep in children has been proposed to account for enhanced consolidation effects, but such studies have typically focused on nocturnal sleep. We examined whether daytime naps benefit word retention in adults and children aged 10–12 years, and whether this relationship in children is affected by differences in white matter pathway microstructure. We hypothesized that the link between memory consolidation and structural brain connectivity will be mediated by the degree of sleep spindles during the nap. Methods Adults (N = 31; mean age = 20.91, SD = 1.55) and children (N = 38; mean age = 11.95, SD = 0.88) learned spoken novel words, followed by a 90-minute nap opportunity monitored with polysomnography. Memory for the words was tested pre- and post-nap. Children’s structural brain connectivity was measured using diffusion tensor imaging (DTI). Results Word memory was preserved following sleep in adults, while an adult wake control condition showed deterioration. Similarly, in children memory performance was stable over the nap, with wake control data currently being collected. Analyses relating behavioral changes over the nap to NREM sleep features and structural brain connectivity will be presented. Conclusion In line with sleep-dependent memory consolidation models, daytime naps protect novel words from forgetting in adults and children. Examining potential relationships between nap-based consolidation and structural integrity has important theoretical implications, given the increase in brain connectivity in language areas during childhood, as well as white matter alterations in developmental populations. Support This research was supported by the UK Economic and Social Research Council, grant no. ES/N009924/1.

Brain connectivity in body dysmorphic disorder compared with controls: a diffusion tensor imaging study

2013 ◽  
Vol 43 (12) ◽  
pp. 2513-2521 ◽  
Author(s):  
B. G. Buchanan ◽  
S. L. Rossell ◽  
J. J. Maller ◽  
W. L. Toh ◽  
S. Brennan ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Body Dysmorphic Disorder ◽  
Diffusion Tensor ◽  
Brain Connectivity ◽  
Imaging Study ◽  
Healthy Controls ◽  
Caudate Nuclei ◽  
White Matter Connectivity ◽  
The Brain

BackgroundSeveral neuroimaging studies have investigated brain grey matter in people with body dysmorphic disorder (BDD), showing possible abnormalities in the limbic system, orbitofrontal cortex, caudate nuclei and temporal lobes. This study takes these findings forward by investigating white matter properties in BDD compared with controls using diffusion tensor imaging. It was hypothesized that the BDD sample would have widespread significantly reduced white matter connectivity as characterized by fractional anisotropy (FA).MethodA total of 20 participants with BDD and 20 healthy controls matched on age, gender and handedness underwent diffusion tensor imaging. FA, a measure of water diffusion within a voxel, was compared between groups on a voxel-by-voxel basis across the brain using tract-based spatial statistics within the FSL package.ResultsResults showed that, compared with healthy controls, BDD patients demonstrated significantly lower FA (p < 0.05) in most major white matter tracts throughout the brain, including in the superior longitudinal fasciculus, inferior fronto-occipital fasciculus and corpus callosum. Lower FA levels could be accounted for by increased radial diffusivity as characterized by eigenvalues 2 and 3. No area of higher FA was found in BDD.ConclusionsThis study provided the first evidence of compromised white matter integrity within BDD patients. This suggests that there are inefficient connections between different brain areas, which may explain the cognitive and emotion regulation deficits within BDD patients.

scholarly journals Repeated Mild Traumatic Brain Injury Results in Long-Term White-Matter Disruption

2014 ◽  
Vol 34 (4) ◽  
pp. 715-723 ◽  
Author(s):  
Virginia Donovan ◽  
Claudia Kim ◽  
Ariana K Anugerah ◽  
Jacqueline S Coats ◽  
Udochuwku Oyoyo ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
White Matter ◽  
Mild Traumatic Brain Injury ◽  
Diffusion Tensor ◽  
Ex Vivo ◽  
Health Concern ◽  
Sprague Dawley ◽  
G Ratio

Mild traumatic brain injury (mTBI) is an increasing public health concern as repetitive injuries can exacerbate existing neuropathology and result in increased neurologic deficits. In contrast to other models of repeated mTBI (rmTBI), our study focused on long-term white-matter abnormalities after bilateral mTBIs induced 7 days apart. A controlled cortical impact (CCI) was used to induce an initial mTBI to the right cortex of Single and rmTBI Sprague Dawley rats, followed by a second injury to the left cortex of rmTBI animals. Shams received only a craniectomy. Ex vivo diffusion tensor imaging (DTI), transmission electron microscopy (TEM), and histology were performed on the anterior corpus callosum at 60 days after injury. The rmTBI animals showed a significant bilateral increase in radial diffusivity (myelin), while only modest changes in axial diffusivity (axonal) were seen between the groups. Further, the rmTBI group showed an increased g-ratio and axon caliber in addition to myelin sheath abnormalities using TEM. Our DTI results indicate ongoing myelin changes, while the TEM data show continuing axonal changes at 60 days after rmTBI. These data suggest that bilateral rmTBI induced 7 days apart leads to progressive alterations in white matter that are not observed after a single mTBI.

scholarly journals Diffusion tensor imaging analysis of the brain in the canine model of Krabbe disease

2016 ◽  
Vol 29 (6) ◽  
pp. 417-424 ◽  
Author(s):  
Allison Bradbury ◽  
David Peterson ◽  
Charles Vite ◽  
Steven Chen ◽  
N Matthew Ellinwood ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Mr Imaging ◽  
Gray Matter ◽  
Diffusion Tensor ◽  
Ex Vivo ◽  
Small Animal ◽  
Krabbe Disease ◽  
Adc Values ◽  
The Brain

Purpose The goal of this study was to compare the diffusion tensor imaging (DTI) metrics from an end-stage canine Krabbe brain evaluated by MR imaging ex vivo to those of a normal dog brain. We hypothesized that the white matter of the canine Krabbe brain would show decreased fractional anisotropy (FA) values and increased apparent diffusion coefficient (ADC) and radial diffusivity (RD) values. Methods An 11-week-old Krabbe dog was euthanized after disease progression. The brain was removed and was placed in a solution of 10% formalin. MR imaging was performed and compared to the brain images of a normal dog that was similarly fixed post-mortem. Both brains were scanned using similar protocols on a 7 T small-animal MRI system. For each brain, maps of ADC, FA, and RD were calculated for 11 white-matter regions and five control gray-matter regions. Results Large decreases in FA values, increases in ADC values, and increases in RD (consistent with demyelination) values, were seen in white matter of the Krabbe brain but not gray matter. ADC values in gray matter of the Krabbe brain were decreased by approximately 29% but increased by approximately 3.6% in white matter of the Krabbe brain. FA values in gray matter were decreased by approximately 3.3% but decreased by approximately 29% in white matter. RD values were decreased by approximately 27.2% in gray matter but increased by approximately 20% in white matter. Conclusion We found substantial abnormalities of FA, ADC, and RD values in an ex vivo canine Krabbe brain.

Identification of Severities of Spinal Cord Injury during Acute Phase in Rats by Diffusion Tensor Imaging

2020 ◽  
Author(s):  
Beike Chen ◽  
Qiang Tan ◽  
Weikang Zhao ◽  
Qiming Yang ◽  
Hongyan Zhang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Diffusion Tensor ◽  
Motor Evoked Potentials ◽  
Ex Vivo ◽  
Female Rats ◽  
Aneurysm Clip ◽  
Cord Injury

Abstract Background: Diffusion tensor imaging (DTI) was an effective method to identify subtle changes to normal‐appearing white matter (WM). Here we analyzed the DTI data with other examinations, including motor evoked potentials (MEPs), histopathological images, and behavioral results, to reflect the lesion development in different degrees of spinal cord injury (SCI) in acute and subacute stage. Method: Except for 2 Sprague -Dawley rats died from anesthesia accident, the rest 42 female rats were randomized into 3 groups: control (n=6), moderate group (n=18), and severe group (n=18). Moderate (a 50-g aneurysm clip with 0.4-mm thickness spacer) or severe (a 50-g aneurysm clip with no spacer) contusion SCI at T8 vertebrae were induced. Then the electrophysiological assessments via MEPs, behavioral deterioration via the Basso, Beattie, and Bresnaha (BBB) scores, DTI data, and histopathology examination were analyzed. Results: In this study, we found that the damage of WM myelin, MEPs amplitude, BBB scores and the decreases in values of fractional anisotropy (FA) and axial diffusivity (AD) were more obvious in the severe injury group than that of the moderate group. Additionally, the FA and AD values could identify the extent of SCI in subacute and early acute SCI respectively, reflected in the robust correlations with MEPs and BBB scores. While the values of radial diffusivity (RD) showed no significant changes. Conclusions: Our data confirmed that DTI was a valuable in ex vivo imaging tool to identify damaged white matter tracts after graded SCI in rat, which may provide useful information for the early identification of the severity of SCI.

White-matter relaxation time and myelin water fraction differences in young adults with autism

2014 ◽  
Vol 45 (4) ◽  
pp. 795-805 ◽  
Author(s):  
S. C. L. Deoni ◽  
J. R. Zinkstok ◽  
E. Daly ◽  
C. Ecker ◽  
S. C. R. Williams ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Brain Connectivity ◽  
Critical Role ◽  
Relaxation Times ◽  
Imaging Study ◽  
Autism Diagnostic Observation Schedule ◽  
Cross Sectional ◽  
Water Fraction ◽  
Myelin Water Fraction

BackgroundIncreasing evidence suggests that autism is associated with abnormal white-matter (WM) anatomy and impaired brain ‘connectivity’. While myelin plays a critical role in synchronized brain communication, its aetiological role in autistic symptoms has only been indirectly addressed by WM volumetric, relaxometry and diffusion tensor imaging studies. A potentially more specific measure of myelin content, termed myelin water fraction (MWF), could provide improved sensitivity to myelin alteration in autism.MethodWe performed a cross-sectional imaging study that compared 14 individuals with autism and 14 age- and IQ-matched controls. T1 relaxation times (T1), T2 relaxation times (T2) and MWF values were compared between autistic subjects, diagnosed using the Autism Diagnostic Interview – Revised (ADI-R), with current symptoms assessed using the Autism Diagnostic Observation Schedule (ADOS) and typical healthy controls. Correlations between T1, T2 and MWF values with clinical measures [ADI-R, ADOS, and the Autism Quotient (AQ)] were also assessed.ResultsIndividuals with autism showed widespread WM T1 and MWF differences compared to typical controls. Within autistic individuals, worse current social interaction skill as measured by the ADOS was related to reduced MWF although not T1. No significant differences or correlations with symptoms were observed with respect to T2.ConclusionsAutistic individuals have significantly lower global MWF and higher T1, suggesting widespread alteration in tissue microstructure and biochemistry. Areas of difference, including thalamic projections, cerebellum and cingulum, have previously been implicated in the disorder; however, this is the first study to specifically indicate myelin alteration in these regions.

scholarly journals White matter microarchitecture and structural network integrity correlate with children intelligence quotient

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ilaria Suprano ◽  
Gabriel Kocevar ◽  
Claudio Stamile ◽  
Salem Hannoun ◽  
Pierre Fourneret ◽  
...  
Keyword(s):  
White Matter ◽  
Intelligence Quotient ◽  
Diffusion Tensor ◽  
Brain Connectivity ◽  
Neuropsychological Testing ◽  
Fiber Bundles ◽  
Parietal Lobes ◽  
Graph Metrics ◽  
High Intelligence ◽  
Iq Scores

AbstractThe neural substrate of high intelligence performances remains not well understood. Based on diffusion tensor imaging (DTI) which provides microstructural information of white matter fibers, we proposed in this work to investigate the relationship between structural brain connectivity and intelligence quotient (IQ) scores. Fifty-seven children (8–12 y.o.) underwent a MRI examination, including conventional T1-weighted and DTI sequences, and neuropsychological testing using the fourth edition of Wechsler Intelligence Scale for Children (WISC-IV), providing an estimation of the Full-Scale Intelligence Quotient (FSIQ) based on four subscales: verbal comprehension index (VCI), perceptual reasoning index (PRI), working memory index (WMI), and processing speed index (PSI). Correlations between the IQ scores and both graphs and diffusivity metrics were explored. First, we found significant correlations between the increased integrity of WM fiber-bundles and high intelligence scores. Second, the graph theory analysis showed that integration and segregation graph metrics were positively and negatively correlated with WISC-IV scores, respectively. These results were mainly driven by significant correlations between FSIQ, VCI, and PRI and graph metrics in the temporal and parietal lobes. In conclusion, these findings demonstrated that intelligence performances are related to the integrity of WM fiber-bundles as well as the density and homogeneity of WM brain networks.

Sign in / Sign up

Export Citation Format

Share Document