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White Matter Regions (white + matter_regions)
Selected AbstractsAge-related white matter lesions are associated with reduction of the apparent diffusion coefficient in the cerebellumEUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2007P. Bugalho Cerebellar apparent diffusion coefficient (ADC) was found to be increased after acute cerebral hemispheric stroke. There are no data on cerebellar ADC changes in patients with chronic, age-related white matter lesions (ARWML). We aimed to determine longitudinal ADC variations on cerebral hemispheric and cerebellar white matter regions of patients with ARWML in order to study relations between ADC changes in both regions. ADC was measured serially (1-year interval) on lesioned periventricular frontal white matter, frontal and parietoccipital normal appearing white matter and middle cerebellar peduncles, on 19 aged patients with ARWML, which also underwent gait assessment. We compared regional ADC at 0 and 1 year and calculated variation percentages for each region. Correlation analysis was made between ADC variation in cerebellar regions and in contralateral hemispheric regions and between cerebellar ADC at 1 year and walking speed. After 1 year, ADC was higher on lesioned periventricular frontal white matter and lower on cerebellar regions. ADC variations on these regions were negatively correlated. Cerebellar ADC measured after 1 year was positively correlated with walking speed. This suggests a link between vascular disease progression inside frontal lesions and ADC reduction in contralateral cerebellar peduncles. Chronic ischemia in frontal white matter could have interrupted frontal-cerebellar circuits, producing hypometabolism in cerebellar regions (and worse performance on motor tasks), decreased perfusion and hence ADC reduction. [source] Association between mitochondrial DNA 10398A>G polymorphism and the volume of amygdalaGENES, BRAIN AND BEHAVIOR, Issue 6 2008H. Yamasue Mitochondrial calcium regulation plays a number of important roles in neurons. Mitochondrial DNA (mtDNA) is highly polymorphic, and its interindividual variation is associated with various neuropsychiatric diseases and mental functions. An mtDNA polymorphism, 10398A>G, was reported to affect mitochondrial calcium regulation. Volume of hippocampus and amygdala is reportedly associated with various mental disorders and mental functions and is regarded as an endophenotype of mental disorders. The present study investigated the relationship between the mtDNA 10398A>G polymorphism and the volume of hippocampus and amygdala in 118 right-handed healthy subjects. The brain morphometry using magnetic resonance images employed both manual tracing volumetry in the native space and voxel-based morphometry (VBM) in the spatially normalized space. Amygdala volume was found to be significantly larger in healthy subjects with 10398A than in those with 10398G by manual tracing, which was confirmed by the VBM. Brain volumes in the other gray matter regions and all white matter regions showed no significant differences associated with the polymorphism. These provocative findings might provide a clue to the complex relationship between mtDNA, brain structure and mental disorders. [source] 3D Mapping of brain differences in native signing congenitally and prelingually deaf subjectsHUMAN BRAIN MAPPING, Issue 7 2010Natasha Leporé Abstract In the prelingual and congenital deaf, functional reorganization is known to occur throughout brain regions normally associated with hearing. However, the anatomical correlates of these changes are not yet well understood. Here, we perform the first tensor-based morphometric analysis of voxel-wise volumetric differences in native signing prelingual and congenitally deaf subjects when compared with hearing controls. We obtained T1-weighted scans for 14 native signing prelingual and congenitally deaf subjects and 16 age- and gender-matched controls. We used linear and fluid registration to align each image to a common template. Using the voxel-wise determinant of the Jacobian of the fluid deformation, significant volume increases, of up to 20%, were found in frontal lobe white matter regions including Broca's area, and adjacent regions involved in motor control and language production. A similar analysis was performed on hand-traced corpora callosa. A strong trend for group differences was found in the area of the splenium considered to carry fibers connecting the temporal (and occipital) lobes. These anatomical differences may reflect experience-mediated developmental differences in myelination and cortical maturation associated with prolonged monomodal sensory deprivation. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source] Functional and anatomical connectivity abnormalities in left inferior frontal gyrus in schizophreniaHUMAN BRAIN MAPPING, Issue 12 2009Bumseok Jeong Abstract Functional studies in schizophrenia demonstrate prominent abnormalities within the left inferior frontal gyrus (IFG) and also suggest the functional connectivity abnormalities in language network including left IFG and superior temporal gyrus during semantic processing. White matter connections between regions involved in the semantic network have also been indicated in schizophrenia. However, an association between functional and anatomical connectivity disruptions within the semantic network in schizophrenia has not been established. Functional (using levels of processing paradigm) as well as diffusion tensor imaging data from 10 controls and 10 chronic schizophrenics were acquired and analyzed. First, semantic encoding specific activation was estimated, showing decreased activation within the left IFG in schizophrenia. Second, functional time series were extracted from this area, and left IFG specific functional connectivity maps were produced for each subject. In an independent analysis, tract-based spatial statistics (TBSS) was used to compare fractional anisotropy (FA) values between groups, and to correlate these values with functional connectivity maps. Schizophrenia patients showed weaker functional connectivity within the language network that includes left IFG and left superior temporal sulcus/middle temporal gyrus. FA was reduced in several white matter regions including left inferior frontal and left internal capsule. Finally, left inferior frontal white matter FA was positively correlated with connectivity measures of the semantic network in schizophrenics, but not in controls. Our results indicate an association between anatomical and functional connectivity abnormalities within the semantic network in schizophrenia, suggesting further that the functional abnormalities observed in this disorder might be directly related to white matter disruptions. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source] Decreasing myelin density reflected increasing white matter pathology in Alzheimer's disease,a neuropathological studyINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 10 2005Martin Sjöbeck Abstract Background White matter disease (WMD) is frequently seen in Alzheimer's disease (AD) at neuropathological examination. It is defined as a subtotal tissue loss with a reduction of myelin, axons and oligodendrocytes as well as astrocytosis. Studies quantitatively defining the myelin loss in AD are scarce. The aim was to develop a method that could provide numerical values of myelin density in AD. The purpose was to compare the myelin contents in increasing grades of pathology of WMD, with age and cortical AD pathology as well as in different regions of the brain in AD. Material and methods Sixteen cases with AD and concomitant WMD were investigated with an in-house developed image analysis technique to determine the myelin attenuation with optical density (OD) in frontoparietal, parietal, temporal and occipital white matter on whole brain coronal sections stained for myelin with Luxol Fast Blue (LFB). The OD values in LFB were compared grouped according to Haematoxylin/Eosin (HE) evaluated mild, moderate and severe WMD or normal tissue. The OD values were also correlated with age and cortical AD pathology and compared between the different studied white matter regions. Results Increasing severity of WMD was associated with a statistically significant OD reduction. No correlation was seen between age and OD or overall cortical AD pathology. The OD values were significantly lower in frontoparietal-compared to occipital white matter. Conclusions Myelin loss in AD with WMD is a marked morphologic component of the disease and it is possible to determine the reduction objectively in neuropathological specimens with quantitative measures. This may be of use for clinical diagnostics including brain imaging. Copyright © 2005 John Wiley & Sons, Ltd. [source] In vivo vascular hallmarks of diffuse leukoaraiosisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2010Jinsoo Uh PhD Abstract Purpose: To characterize multiple patterns of vascular changes in leukoaraiosis using in vivo magnetic resonance imaging (MRI) techniques. Materials and Methods: We measured cerebral blood flow (CBF), cerebrovascular reactivity (CVR), and blood,brain-barrier (BBB) leakage in a group of 33 elderly subjects (age: 72.3 ± 6.8 years, 17 males, 16 females). Leukoaraiosis brain regions were identified in each subject using fluid-attenuated inversion-recovery (FLAIR) MRI. Vascular parameters in the leukoaraiosis regions were compared to those in the normal-appearing white matter (NAWM) regions. Vascular changes in leukoaraiosis were also compared to structural damage as assessed by diffusion tensor imaging. Results: CBF and CVR in leukoaraiosis regions were found to be 39.7 ± 5.2% (P < 0.001) and 52.5 ± 11.6% (P = 0.005), respectively, of those in NAWM. In subjects who did not have significant leukoaraiosis, CBF and CVR in regions with high risk for leukoaraiosis showed a slight reduction compared to the other white matter regions. Significant BBB leakage was also detected (P = 0.003) in leukoaraiosis and the extent of BBB leakage was positively correlated with mean diffusivity. In addition, CVR in NAWM was lower than that in white matter of subjects without significant leukoaraiosis. Conclusion: Leukoaraiosis was characterized by reduced CBF, CVR, and a leakage in the BBB. J. Magn. Reson. Imaging 2010;32:184,190. © 2010 Wiley-Liss, Inc. [source] In vivo quantitative proton MRSI study of brain development from childhood to adolescence,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2002Alena Horská PhD Abstract Purpose To quantify regional variations in metabolite levels in the developing brain using quantitative proton MR spectroscopic imaging (MRSI). Materials and Methods Fifteen healthy subjects three to 19 years old were examined by in vivo multislice proton MRSI. Concentrations of N-acetyl aspartate (NAA), total choline (Cho), total creatine (Cr), and peak area ratios were determined in selected frontal and parietal gray and white matter regions, basal ganglia, and thalamus. Results In cortical gray matter regions, the ratio of NAA/Cho increased to a maximum at 10 years and decreased thereafter (P = 0.010). In contrast, in white matter, average ratios NAA/Cho increased linearly with age (P = 0.045). In individual brain regions, age-related changes in NAA/Cho were found in the putamen (P = 0.044). No significant age-related changes in NAA, Cho, Cr, or other metabolite ratios could be determined. Conclusion Consistent with recent studies using other structural and functional neuroimaging techniques, our data suggest that small but significant changes occur in regional cerebral metabolism during childhood and adolescence. Non-linear age related changes of NAA/Cho in frontal and parietal areas, resembling previously reported age related changes in rates of glucose utilization and cortical volumes, may be associated with dendritic and synaptic development and regression. Linear age-related changes of NAA/Cho in white matter are also in agreement with age-related increases in white matter volumes, and may reflect progressive increases in axonal diameter and myelination. J. Magn. Reson. Imaging 2002;15:137,143. Published 2002 Wiley-Liss, Inc. [source] Metabolite proton T2 mapping in the healthy rhesus macaque brain at 3 TMAGNETIC RESONANCE IN MEDICINE, Issue 5 2009Songtao Liu Abstract The structure and metabolism of the rhesus macaque brain, an advanced model for neurologic diseases and their treatment response, is often studied noninvasively with MRI and 1H-MR spectroscopy. Due to the shorter transverse relaxation time (T2) at the higher magnetic fields these studies favor, the echo times used in 1H-MR spectroscopy subject the metabolites to unknown T2 weighting, decreasing the accuracy of quantification which is key for inter- and intra-animal comparisons. To establish the "baseline" (healthy animal) T2 values, we mapped them for the three main metabolites' T2s at 3 T in four healthy rhesus macaques and tested the hypotheses that their mean values are similar (i) among animals; and (ii) to analogs regions in the human brain. This was done with three-dimensional multivoxel 1H-MR spectroscopy at (0.6 × 0.6 × 0.5 cm)3 = 180 ,L spatial resolution over a 4.2 × 3.0 × 2.0 = 25 cm3 (,30%) of the macaque brain in a two-point protocol that optimizes T2 precision per unit time. The estimated T2s in several gray and white matter regions are all within 10% of those reported in the human brain (mean ± standard error of the mean): N -acetylaspartate = 316 ± 7, creatine = 177 ± 3, and choline = 264 ± 9 ms, with no statistically significant gray versus white matter differences. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Synapses on NG2-expressing progenitors in the brain: multiple functions?THE JOURNAL OF PHYSIOLOGY, Issue 16 2008Vittorio Gallo Progenitor cells expressing the proteoglycan NG2 represent approximately 5% of the total cells in the adult brain, and are found both in grey and white matter regions where they give rise to oligodendrocytes. The finding that these cells receive synaptic contacts from excitatory and inhibitory neurons has not only raised major interest in the possible roles of these synapses, but also stimulated further research on the developmental and cellular functions of NG2-expressing (NG2+) progenitors themselves in the context of neural circuit physiology. Here we review recent findings on the functional properties of the synapses on NG2+ cells in grey and white matter regions of the brain. In this review article we make an attempt to integrate current knowledge on the cellular and developmental properties of NG2+ progenitors with the functional attributes of their synapses, in order to understand the physiological relevance of neuron,NG2+ progenitor signal transmission. We propose that, although NG2+ progenitors receive synaptic contact in all brain regions where they are found, their synapses might have different developmental and functional roles, probably reflecting the distinct functions of NG2+ progenitors in the brain. [source] Diffusion-weighted magnetic resonance imaging of white matter in bipolar disorder: a pilot studyBIPOLAR DISORDERS, Issue 2 2006William T Regenold Objective:, Diffusion-weighted magnetic resonance imaging (MRI) has shown increased sensitivity in detecting brain white matter disease compared to traditional T2-weighted MRI. Diffusion-weighted imaging (DWI) can quantitatively assess the microstructural integrity of white matter using the average apparent diffusion coefficient (ADCav), a measure of the extent to which water molecules move freely within tissue. On the basis of numerous studies suggesting white matter disease in bipolar patients, particularly patients with more severe illness, this study aimed to test the utility of DWI in assessing the white matter integrity of bipolar patients with severe illness. Methods:, The existing MRI scans of eight bipolar patients and eight age-matched controls with neurological illness were examined retrospectively. ADCav values for pixels within white matter regions of interest (ROIs) were calculated and used to plot ADCav frequency histograms for each ROI. Mean ADCav values for the two groups were then compared by ANCOVA. Results:, The bipolar mean ADCav (0.855 ± 0.051 × 10,3 mm2/s) for combined white matter ROIs significantly exceeded that of controls (0.799 ± 0.046 × 10,3 mm2/s), while covarying for age (F = 4.47, df = 3, p = 0.025). Conclusions:, This is the first report of an elevated ADCav in the white matter of a group of patients with bipolar disorder. In this group of patients with severe illness, increased white matter ADCav suggests microstructural changes consistent with decreased white matter integrity. DWI may be an additional, useful tool to assess white matter abnormalities in bipolar disorder. [source] Brain magnetic resonance imaging abnormalities in neuromyelitis opticaACTA NEUROLOGICA SCANDINAVICA, Issue 4 2008Y. Li Objective,,, Brain abnormalities in neuromyelitis optica (NMO) attracted much attention. Our study was to identify the brain magnetic resonance imaging (MRI) abnormalities in Chinese NMO patients. Methods,,, Patients who fulfilled the latest diagnostic criteria of NMO proposed by Wingerchuk et al. [Neurology 66 (2006) 1485] and whose brain MRI did not meet the multiple sclerosis (MS) criteria of McDonald et al. [Ann Neurol 50 (2001) 121] were selected to perform MRI scanning of the brain, spinal cord and optic nerves. Results,,, Twenty-eight of 33 patients (84.8%) had abnormal MRI findings. Twenty-two patients (66.7%) presented with well-defined brain parenchymal lesions and the other six patients (18.2%) with macroscopic symmetrical diffuse hyperintensities in deep white matter. Fifteen of 22 patients had more than one lesion (,2 lesions) and the other seven patients had single lesion. In the supratentorium, most lesions were punctate or small round dot and non-specific in juxtacortical, subcortical and deep white matter regions, a few were patchy atypical confluent lesions. Brainstem was easily involved (14/33, 42.4%) especially in medulla (7/33, 21.2%). Conclusions,,, This study demonstrates the characteristics of brain MRI abnormalities in Chinese NMO patients, which are helpful to the revision of diagnostic criteria for NMO. [source] Rey Visual Design Learning Test performance correlates with white matter structureACTA NEUROPSYCHIATRICA, Issue 2 2009Stefan Begré Objective:, Studies exploring relation of visual memory to white matter are extensively lacking. The Rey Visual Design Learning Test (RVDLT) is an elementary motion, colour and word independent visual memory test. It avoids a significant contribution from as many additional higher order visual brain functions as possible to visual performance, such as three-dimensional, colour, motion or word-dependent brain operations. Based on previous results, we hypothesised that test performance would be related with white matter of dorsal hippocampal commissure, corpus callosum, posterior cingulate, superior longitudinal fascicle and internal capsule. Methods:, In 14 healthy subjects, we measured intervoxel coherence (IC) by diffusion tensor imaging as an indication of connectivity and visual memory performance measured by the RVDLT. IC considers the orientation of the adjacent voxels and has a better signal-to-noise ratio than the commonly used fractional anisotropy index. Results:, Using voxelwise linear regression analyses of the IC values, we found a significant and direct relationship between 11 clusters and visual memory test performance. The fact that memory performance correlated with white matter structure in left and right dorsal hippocampal commissure, left and right posterior cingulate, right callosal splenium, left and right superior longitudinal fascicle, right medial orbitofrontal region, left anterior cingulate, and left and right anterior limb of internal capsule emphasises our hypothesis. Conclusion:, Our observations in healthy subjects suggest that individual differences in brain function related to the performance of a task of higher cognitive demands might partially be associated with structural variation of white matter regions. [source] | |||||||||||||||||||||||||