scholarly journals More Highly Myelinated White Matter Tracts are Associated with Faster Processing Speed in Healthy Adults

2017 ◽  
Author(s):  
Sidhant Chopra ◽  
Marnie Shaw ◽  
Thomas Shaw ◽  
Perminder S Sachdev ◽  
Kaarin J Anstey ◽  
...  
Keyword(s):  
White Matter ◽  
Corpus Callosum ◽  
Processing Speed ◽  
Middle Age ◽  
Principal Component ◽  
Internal Capsule ◽  
White Matter Tracts ◽  
Healthy Older Adults ◽  
Corona Radiata

AbstractThe objective of this study was to investigate whether the myelin content of white matter tracts is predictive of cogni–tive processing speed and whether such associations are modulated by age. Associations between myelin content and processing speed was assessed in 570 community-living individuals (277 middle-age, 293 older-age). Myelin content was measured using the mean T1w/T2w magnetic resonance ratio, in six white matter tracts (anterior corona radiata, superior corona radiata, pontine crossing tract, anterior limb of the internal capsule, genu of the corpus callosum, and splenium of the corpus callosum). Processing speed was estimated by extracting a principal component from 5 sep–arate tests of processing speed. It was found that myelin content of the bilateral anterior limb of the internal capsule and left splenium of the corpus callosum were significant predictors of processing speed, even after controlling for socio-demographic, health and genetic variables and correcting for multiple comparisons. A 1 SD increase in the myelin content of the anterior limb of the internal capsule was associated with 2.53% increase in processing speed and within the left splenium of the corpus callosum with a 2.20% increase in processing speed. In addition, significant differences in myelin content between middle-age and older participants were found in all six white matter tracts. The present results indicate that myelin content, estimated in vivo using a neuroimaging approach in healthy older adults is sufficiently precise to predict variability in processing speed in behavioural measures.

scholarly journals Analysis of Age-Related White Matter Microstructures Based on Diffusion Tensor Imaging

2021 ◽  
Vol 13 ◽  
Author(s):  
Yahui Ouyang ◽  
Dong Cui ◽  
Zilong Yuan ◽  
Zhipeng Liu ◽  
Qing Jiao ◽  
...  
Keyword(s):  
White Matter ◽  
Fiber Length ◽  
Middle Age ◽  
Diffusion Tensor ◽  
Age Groups ◽  
Internal Capsule ◽  
Fiber Tracking ◽  
Posterior Limb ◽  
Corona Radiata ◽  
Age Related

Population aging has become a serious social problem. Accordingly, many researches are focusing on changes in brains of the elderly. In this study, we used multiple parameters to analyze age-related changes in white matter fibers. A sample cohort of 58 individuals was divided into young and middle-age groups and tract-based spatial statistics (TBSS) were used to analyze the differences in fractional anisotropy (FA), mean diffusion (MD), axial diffusion (AD), and radial diffusion (RD) between the two groups. Deterministic fiber tracking was used to investigate the correlation between fiber number and fiber length with age. The TBSS analysis revealed significant differences in FA, MD, AD, and RD in multiple white matter fibers between the two groups. In the middle-age group FA and AD were lower than in young people, whereas the MD and RD values were higher. Deterministic fiber tracking showed that the fiber length of some fibers correlated positively with age. These fibers were observed in the splenium of corpus callosum (SCC), the posterior limb of internal capsule (PLIC), the right posterior corona radiata (PCR_R), the anterior corona radiata (ACR), the left posterior thalamic radiation (include optic radiation; PTR_L), and the left superior longitudinal fasciculus (SLF_L), among others. The results showed that the SCC, PLIC, PCR_R, ACR, PTR_L, and SLF_L significantly differed between young and middle-age people. Therefore, we believe that these fibers could be used as image markers of age-related white matter changes.

scholarly journals In vivo Magnetization Transfer MRI Shows Dysmyelination in an Ischemic Mouse Model of Periventricular Leukomalacia

2011 ◽  
Vol 31 (10) ◽  
pp. 2009-2018 ◽  
Author(s):  
Ali Fatemi ◽  
Mary Ann Wilson ◽  
Andre W Phillips ◽  
Michael T McMahon ◽  
Jiangyang Zhang ◽  
...  
Keyword(s):  
White Matter ◽  
Corpus Callosum ◽  
Mouse Model ◽  
Magnetization Transfer ◽  
Periventricular Leukomalacia ◽  
Internal Capsule ◽  
Artery Ligation ◽  
Magnetization Transfer Mri ◽  
The Right

Periventricular leukomalacia, PVL, is the leading cause of cerebral palsy in prematurely born infants, and therefore more effective interventions are required. The objective of this study was to develop an ischemic injury model of PVL in mice and to determine the feasibility of in vivo magnetization transfer (MT) magnetic resonance imaging (MRI) as a potential monitoring tool for the evaluation of disease severity and experimental therapeutics. Neonatal CD-1 mice underwent unilateral carotid artery ligation on postnatal day 5 (P5); at P60, in vivo T2-weighted (T2w) and MT-MRI were performed and correlated with postmortem histopathology. In vivo T2w MRI showed thinning of the right corpus callosum, but no significant changes in hippocampal and hemispheric volumes. Magnetization transfer MRI revealed significant white matter abnormalities in the bilateral corpus callosum and internal capsule. These quantitative MT-MRI changes correlated highly with postmortem findings of reduced myelin basic protein in bilateral white matter tracts. Ventriculomegaly and persistent astrogliosis were observed on the ligated side, along with evidence of axonopathy and fewer oligodendrocytes in the corpus callosum. We present an ischemia-induced mouse model of PVL, which has pathologic abnormalities resembling autopsy reports in infants with PVL. We further validate in vivo MRI techniques as quantitative monitoring tools that highly correlate with postmortem histopathology.

Diffusion tensor imaging in hyperthyroidism: assessment of microstructural white matter abnormality with a tract-based spatial statistical analysis

2020 ◽  
Vol 61 (12) ◽  
pp. 1677-1683 ◽  
Author(s):  
Kerim Aslan ◽  
Hediye Pinar Gunbey ◽  
Sumeyra Cortcu ◽  
Onur Ozyurt ◽  
Ugur Avci ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Corpus Callosum ◽  
Diffusion Tensor ◽  
Mean Diffusivity ◽  
Imaging Study ◽  
Internal Capsule ◽  
Control Group ◽  
Corona Radiata ◽  
Microstructural Alterations

Background Metabolic, morphological, and functional brain changes associated with a neurological deficit in hyperthyroidism have been observed. However, changes in microstructural white matter (WM), which can explain the underlying pathophysiology of brain dysfunctions, have not been researched. Purpose To assess microstructural WM abnormality in patients with untreated or newly diagnosed hyperthyroidism using tract-based spatial statistics (TBSS). Material and Methods Eighteen patients with hyperthyroidism and 14 age- and sex-matched healthy controls were included in this study. TBSS were used in this diffusion tensor imaging study for a whole-brain voxel-wise analysis of fractional anisotropy, mean diffusivity, axial diffusivity (AD), and radial diffusivity (RD) of WM. Results When compared to the control group, TBSS showed a significant increase in the RD of the corpus callosum, anterior and posterior corona radiata, posterior thalamic radiation, cingulum, superior longitudinal fasciculus, and the retrolenticular region of the internal capsule in patients with hyperthyroidism ( P < 0.05), as well as a significant decrease in AD in the anterior corona radiata and the genu of corpus callosum ( P < 0.05). Conclusion This study showed that more regions are affected by the RD increase than the AD decrease in the WM tracts of patients with hyperthyroidism. These preliminary results suggest that demyelination is the main mechanism of microstructural alterations in the WM of hyperthyroid patients.

Changes in mild cognitive impairment and its subtypes as seen on diffusion tensor imaging

2012 ◽  
Vol 24 (9) ◽  
pp. 1483-1493 ◽  
Author(s):  
Senthil Thillainadesan ◽  
Wei Wen ◽  
Lin Zhuang ◽  
John Crawford ◽  
Nicole Kochan ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
White Matter ◽  
Multiple Testing ◽  
Diffusion Tensor ◽  
Internal Capsule ◽  
Anterior Cingulate ◽  
Corona Radiata ◽  
Amnestic Mci ◽  
Subcortical Regions ◽  
The Right

ABSTRACTBackground: Previous studies using diffusion tensor imaging (DTI) have observed microstructural abnormalities in white matter regions in both Alzheimer's disease and mild cognitive impairment (MCI). The aim of this work was to examine the abnormalities in white matter and subcortical regions of MCI and its subtypes in a large, community-dwelling older aged cohortMethods: A community-based sample of 396 individuals without dementia underwent medical assessment, neuropsychiatric testing, and neuroimaging. Of these, 158 subjects were classified as MCI and 238 as cognitively normal (controls) based on international MCI consensus criteria. Regional fractional anisotropy (FA) and mean diffusivity (MD) measures were calculated from the DTI and compared between groups. The false discovery rate correction was applied for multiple testing.Results: Subjects with MCI did not have significant differences in FA compared with controls after correction for multiple testing, but had increased MD in the right putamen, right anterior limb of the internal capsule, genu and splenium of the corpus callosum, right posterior cingulate gyrus, left superior frontal gyrus, and right and left corona radiata. When compared with controls, changes in left anterior cingulate, left superior frontal gyrus, and right corona radiata were associated with amnestic MCI (aMCI), whereas changes in the right putamen, right anterior limb of the internal capsule, and the right corona radiata were associated with non-amnestic MCI (naMCI). On logistic regression, the FA values in the left superior gyrus and MD values in the anterior cingulate distinguished aMCI from naMCI.Conclusions: MCI is associated with changes in white matter and subcortical regions as seen on DTI. Changes in some anterior brain regions distinguish aMCI from naMCI.

scholarly journals Childhood adversity associated with white matter alteration in the corpus callosum, corona radiata, and uncinate fasciculus of psychiatrically healthy adults

2017 ◽  
Vol 12 (2) ◽  
pp. 449-458 ◽  
Author(s):  
Simon McCarthy-Jones ◽  
◽  
Lena K. L. Oestreich ◽  
Amanda E. Lyall ◽  
Zora Kikinis ◽  
...  
Keyword(s):  
White Matter ◽  
Corpus Callosum ◽  
Childhood Adversity ◽  
Healthy Adults ◽  
Uncinate Fasciculus ◽  
Corona Radiata

On the microstructural origin of brain white matter hydraulic permeability

2021 ◽  
Vol 118 (36) ◽  
pp. e2105328118
Author(s):  
Marco Vidotto ◽  
Andrea Bernardini ◽  
Marco Trovatelli ◽  
Elena De Momi ◽  
Daniele Dini
Keyword(s):  
White Matter ◽  
Corpus Callosum ◽  
Drug Transport ◽  
Three Dimensional ◽  
Principal Component ◽  
Hydraulic Permeability ◽  
Convection Enhanced Delivery ◽  
Brain White Matter ◽  
Significant Difference ◽  
The Brain

Brain microstructure plays a key role in driving the transport of drug molecules directly administered to the brain tissue, as in Convection-Enhanced Delivery procedures. The proposed research analyzes the hydraulic permeability of two white matter (WM) areas (corpus callosum and fornix) whose three-dimensional microstructure was reconstructed starting from the acquisition of electron microscopy images. We cut the two volumes with 20 equally spaced planes distributed along two perpendicular directions, and, on each plane, we computed the corresponding permeability vector. Then, we considered that the WM structure is mainly composed of elongated and parallel axons, and, using a principal component analysis, we defined two principal directions, parallel and perpendicular, with respect to the axons’ main direction. The latter were used to define a reference frame onto which the permeability vectors were projected to finally obtain the permeability along the parallel and perpendicular directions. The results show a statistically significant difference between parallel and perpendicular permeability, with a ratio of about two in both the WM structures analyzed, thus demonstrating their anisotropic behavior. Moreover, we find a significant difference between permeability in corpus callosum and fornix, which suggests that the WM heterogeneity should also be considered when modeling drug transport in the brain. Our findings, which demonstrate and quantify the anisotropic and heterogeneous character of the WM, represent a fundamental contribution not only for drug-delivery modeling, but also for shedding light on the interstitial transport mechanisms in the extracellular space.

scholarly journals Combining Hypothermia and Oleuropein Subacutely Protects Subcortical White Matter in a Swine Model of Neonatal Hypoxic-Ischemic Encephalopathy

2020 ◽  
Author(s):  
Jennifer K Lee ◽  
Polan T Santos ◽  
May W Chen ◽  
Caitlin E O’Brien ◽  
Ewa Kulikowicz ◽  
...  
Keyword(s):  
White Matter ◽  
Motor Cortex ◽  
Corpus Callosum ◽  
Internal Capsule ◽  
Subcortical White Matter ◽  
White Matter Injury ◽  
Swine Model ◽  
Cortex Neuron ◽  
Motor Cortex Neuron ◽  
Ischemic Encephalopathy

Abstract Neonatal hypoxia-ischemia (HI) causes white matter injury that is not fully prevented by therapeutic hypothermia. Adjuvant treatments are needed. We compared myelination in different piglet white matter regions. We then tested whether oleuropein (OLE) improves neuroprotection in 2- to 4-day-old piglets randomized to undergo HI or sham procedure and OLE or vehicle administration beginning at 15 minutes. All groups received overnight hypothermia and rewarming. Injury in the subcortical white matter, corpus callosum, internal capsule, putamen, and motor cortex gray matter was assessed 1 day later. At baseline, piglets had greater subcortical myelination than in corpus callosum. Hypothermic HI piglets had scant injury in putamen and cerebral cortex. However, hypothermia alone did not prevent the loss of subcortical myelinating oligodendrocytes or the reduction in subcortical myelin density after HI. Combining OLE with hypothermia improved post-HI subcortical white matter protection by preserving myelinating oligodendrocytes, myelin density, and oligodendrocyte markers. Corpus callosum and internal capsule showed little HI injury after hypothermia, and OLE accordingly had minimal effect. OLE did not affect putamen or motor cortex neuron counts. Thus, OLE combined with hypothermia protected subcortical white matter after HI. As an adjuvant to hypothermia, OLE may subacutely improve regional white matter protection after HI.

scholarly journals In vivo DTI evaluation of white matter tracts in rat spinal cord

2006 ◽  
Vol 24 (1) ◽  
pp. 231-234 ◽  
Author(s):  
Jayaroop Gullapalli ◽  
Jaroslaw Krejza ◽  
Eric D. Schwartz
Keyword(s):  
Spinal Cord ◽  
White Matter ◽  
Rat Spinal Cord ◽  
White Matter Tracts

Microsurgical Anatomy of the White Matter Tracts in Hemispherotomy

2014 ◽  
Vol 10 (2) ◽  
pp. 305-324 ◽  
Author(s):  
Baris Kucukyuruk ◽  
Kaan Yagmurlu ◽  
Necmettin Tanriover ◽  
Mustafa Uzan ◽  
Albert L. Rhoton
Keyword(s):  
White Matter ◽  
Anterior Commissure ◽  
Posterior Part ◽  
Internal Capsule ◽  
Epileptic Seizures ◽  
Microsurgical Anatomy ◽  
Subcortical Structures ◽  
Posterior Edge ◽  
White Matter Tracts ◽  
Posterior Limb

Abstract BACKGROUND: Hemispherotomy is a surgical procedure performed for refractory epileptic seizures due to wide hemispheric damage. OBJECTIVE: To describe the microanatomy of the white matter tracts transected in a hemispherotomy and the relationship of the surgical landmarks used during the intraventricular callosotomy. METHODS: The cortical and subcortical structures were examined in 32 hemispheres. RESULTS: Incision of the temporal stem along the inferior limiting sulcus crosses the insulo-opercular fibers, uncinate, inferior occipitofrontal and middle longitudinal fasciculi, anterior commissure, and optic and auditory radiations. The incision along the superior limiting sulcus transects insulo-opercular fibers and the genu and posterior limb of internal capsule. The incision along the anterior limiting sulcus crosses the insulo-opercular fibers, anterior limb of the internal capsule, anterior commissure, and the anterior thalamic bundle. The disconnection of the posterior part of the corpus callosum may be incomplete if the point at which the last cortical branch of the anterior cerebral artery (ACA) turns upward and disappears from the view through the intraventricular exposure is used as the landmark for estimating the posterior extent of the callosotomy. This ACA branch turns upward before reaching the posterior edge of the splenium in 85% of hemispheres. The falx, followed to the posterior edge of the splenium, is a more reliable landmark for completing the posterior part of an intraventricular callosotomy. CONCLUSION: The fiber tracts disconnected in hemispherotomy were reviewed. The falx is a more reliable guide than the ACA in completing the posterior part of the intraventricular callosotomy.

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