Showing papers on "Inferior longitudinal fasciculus published in 2013"
TL;DR: The combination of functional responses from cortex and anatomical measures in the white matter provides an overview of how the written word is encoded and communicated along the ventral occipital-temporal circuitry for seeing words.
216 citations
TL;DR: The left arcuate fasciculus, which connects anterior and posterior language regions of the human brain and which has been previously associated with reading ability in older individuals, is already smaller and has less integrity in kindergartners who are at risk for dyslexia because of poor phonological awareness.
Abstract: Developmental dyslexia, an unexplained difficulty in learning to read, has been associated with alterations in white matter organization as measured by diffusion-weighted imaging. It is unknown, however, whether these differences in structural connectivity are related to the cause of dyslexia or if they are consequences of reading difficulty (e.g., less reading experience or compensatory brain organization). Here, in 40 kindergartners who had received little or no reading instruction, we examined the relation between behavioral predictors of dyslexia and white matter organization in left arcuate fasciculus, inferior longitudinal fasciculus, and the parietal portion of the superior longitudinal fasciculus using probabilistic tractography. Higher composite phonological awareness scores were significantly and positively correlated with the volume of the arcuate fasciculus, but not with other tracts. Two other behavioral predictors of dyslexia, rapid naming and letter knowledge, did not correlate with volumes or diffusion values in these tracts. The volume and fractional anisotropy of the left arcuate showed a particularly strong positive correlation with a phoneme blending test. Whole-brain regressions of behavioral scores with diffusion measures confirmed the unique relation between phonological awareness and the left arcuate. These findings indicate that the left arcuate fasciculus, which connects anterior and posterior language regions of the human brain and which has been previously associated with reading ability in older individuals, is already smaller and has less integrity in kindergartners who are at risk for dyslexia because of poor phonological awareness. These findings suggest a structural basis of behavioral risk for dyslexia that predates reading instruction.
198 citations
TL;DR: Comparisons of white matter integrity and gray matter volumetric patterns of older adult lifelong bilinguals and monolinguals suggest that lifelong bilingualism contributes to CR against WM integrity declines in aging.
158 citations
TL;DR: WM integrity changes were found in areas that are highly relevant for cognition in the CI patients but not in the CP patients, suggesting that DTI might be a powerful tool when monitoring cognitive impairment in MS.
Abstract: Objective: To investigate whether extent and severity of white matter (WM) damage, as measured with diffusion tensor imaging (DTI), can distinguish cognitively preserved (CP) from cognitively impaired (CI) multiple sclerosis (MS) patients Methods: Conventional MRI and DTI data were acquired from 55 MS patients (35 CP, 20 CI) and 30 healthy controls (HC) Voxelwise analyses were used to investigate fractional anisotropy (FA), mean diffusivity, radial diffusivity, and axial diffusivity of a WM skeleton Regional gray matter volume was quantified and lesion probability maps were generated Results: Compared to HCs, decreased FA was found in 49% of the investigated WM skeleton in CP patients and in 76% of the investigated WM in CI patients Several brain areas that showed reduced FA in both patient groups were significantly worse in CI patients, ie, corpus callosum, superior and inferior longitudinal fasciculus, corticospinal tracts, forceps major, cingulum, and fornices In CI patients, WM integrity damage was additionally seen in cortical brain areas, thalamus, uncinate fasciculus, brainstem, and cerebellum These findings were independent of lesion location and regional gray matter volume, since no differences were found between the groups Conclusion: CI patients diverged from CP patients only on DTI metrics WM integrity changes were found in areas that are highly relevant for cognition in the CI patients but not in the CP patients These WM changes are therefore thought to be related to the cognitive deficits and suggest that DTI might be a powerful tool when monitoring cognitive impairment in MS
154 citations
TL;DR: Findings suggest that DTI tractography enables anatomical definition of region of interest (ROI) for correlation of behavioral parameters with diffusion indices, and functionality can be correlated with white matter integrity.
Abstract: The ability to perform complex as well as simple cognitive tasks engages a network of brain regions that is mediated by the white matter fiber bundles connecting them. Different cognitive tasks employ distinctive white matter fiber bundles. The temporal lobe and its projections subserve a variety of key functions known to deteriorate during aging. In a cohort of 52 healthy subjects (ages 25–82 years), we performed voxel-wise regression analysis correlating performance in higher-order cognitive domains (executive function, information processing speed, and memory) with white matter integrity, as measured by diffusion tensor imaging (DTI) fiber tracking in the temporal lobe projections [uncinate fasciculus (UF), fornix, cingulum, inferior longitudinal fasciculus (ILF), and superior longitudinal fasciculus (SLF)]. The fiber tracts were spatially registered and statistical parametric maps were produced to spatially localize the significant correlations. Results showed that performance in the executive function domain is correlated with DTI parameters in the left SLF and right UF; performance in the information processing speed domain is correlated with fractional anisotropy (FA) in the left cingulum, left fornix, right and left ILF and SLF; and the memory domain shows significant correlations with DTI parameters in the right fornix, right cingulum, left ILF, left SLF and right UF. These findings suggest that DTI tractography enables anatomical definition of region of interest (ROI) for correlation of behavioral parameters with diffusion indices, and functionality can be correlated with white matter integrity.
136 citations
TL;DR: It is suggested that GSK3-β inhibition and lithium could counteract the detrimental influences of BD on WM structure, with specific benefits resulting from effects on specific WM tracts contributing to the functional integrity of the brain and involving interhemispheric, limbic, and large frontal, parietal, and fronto-occipital connections.
134 citations
TL;DR: The middle longitudinal fasciculus, connects the angular gyrus and the superior temporal Gyrus and its course can be systematically differenciated from those of other fascicles composing both ventral and dorsal routes (IFOF, IFL, AF and UF).
108 citations
TL;DR: The UF mediates semantic control during word comprehension by connecting regions specialized for cognitive control with those storing word meanings, and these findings support a relationship between structural and functional connectivity measures.
98 citations
TL;DR: Tract alterations were more extensive than gray matter alterations, and the extent of alteration across tracts and PPA syndromes varied between diffusivity metrics, illustrating the selective vulnerability of brain language networks in these diseases.
98 citations
TL;DR: It is suggested that brain structures involving OFC, together with other regions, contribute to the maintenance of effective EFEEs among non-clinical subjects.
Abstract: Executive functions involve control processes such as goal-oriented planning, flexible strategy generation, sustaining set maintenance, self-monitoring, and inhibition. Executive functions during everyday events (EFEEs) are distinct from those measured under laboratory settings; the former can be severely impaired while the latter remain intact. Non-routine everyday problems due to executive dysfunctions affect individual functioning in everyday life and are of great clinical interest. Despite the importance of anatomical bases underlying better EFEEs, such bases have never been investigated among non-clinical samples. Using voxel-based morphometry to measure regional gray matter volume (rGMV) and regional white matter volume (rWMV) and diffusion tensor imaging to determine fractional anisotropy values, we identified the anatomical correlates of better EFEEs using the Dysexecutive Questionnaire in 303 normal young subjects (168 men and 135 women). Better EFEEs were associated with a smaller rGMV in the orbitofrontal cortex (OFC) spread across Brodmann areas (BA) 25, 11, and 12 and larger rWMV in the WM area of OFC adjacent to BA 11. Furthermore, individual EFEEs were positively associated with rWMV in the temporal areas, primarily the inferior longitudinal fasciculus and inferior fronto-occipital fasciculus, the latter of which connects OFC and posterior regions. Thus, our findings suggest that brain structures involving OFC, together with other regions, contribute to the maintenance of effective EFEEs among non-clinical subjects.
85 citations
TL;DR: The TPFIA is a critical neural crossroad; it is traversed by 7 white matter tracts that connect multiple areas of the ipsilateral and contralateral hemisphere and is also a vulnerable part of the network in that a lesion within this area will produce multiple disconnections.
Abstract: Background Lesion studies and recent surgical series report important sequelae when the inferior parietal lobe and posterior temporal lobe are damaged. Millions of axons cross through the white matter underlying these cortical areas; however, little is known about the complex organization of these connections. Objective To analyze the subcortical anatomy of a specific region within the parietal and temporal lobes where 7 long-distances tracts intersect, ie, the temporoparietal fiber intersection area (TPFIA). Methods Four postmortem human hemispheres were dissected, and 4 healthy hemispheres were analyzed through the use of diffusion tensor imaging--based tractography software. The different tracts that intersect at the posterior temporal and parietal lobes were isolated, and the relations with the surrounding structures were analyzed. Results Seven tracts pass through the TPFIA: horizontal portion of the superior longitudinal fasciculus, arcuate fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, optic radiations, and tapetum. The TPFIA was located deep to the angular gyrus, posterior portion of the supramarginal gyrus, and posterior portion of the superior, middle, and inferior temporal gyri. Conclusion The TPFIA is a critical neural crossroad; it is traversed by 7 white matter tracts that connect multiple areas of the ipsilateral and contralateral hemisphere. It is also a vulnerable part of the network in that a lesion within this area will produce multiple disconnections. This is valuable information when a surgical approach through the parieto-temporo-occipital junction is planned. To decrease surgical risks, a detailed diffusion tensor imaging tractography reconstruction of the TPFIA should be performed, and intraoperative electric stimulation should be strongly considered.
TL;DR: The results of this study show that young adult patients with schizophrenia did not differ in mean FA from healthy controls along WM fibers; siblings of patients showed higher mean FA in the left and right arcuate fasciculus as compared to patients and controls.
TL;DR: In this paper, the authors examined the contribution of ADHD familial liability to white matter microstructure using diffusion tensor imaging (DTI) tractography, and they found that disruptions in white matter pathways occur in several large white-matter pathways in association with ADHD and indicate a familial liability for the disorder.
Abstract: Objective Previous voxel-based and regions-of-interest (ROI)–based diffusion tensor imaging (DTI) studies have found above-normal mean diffusivity (MD) and below-normal fractional anisotropy (FA) in subjects with attention-deficit/hyperactivity disorder (ADHD). However, findings remain mixed, and few studies have examined the contribution of ADHD familial liability to white matter microstructure. Method We used refined DTI tractography methods to examine MD, FA, axial diffusivity (AD), and radial diffusivity (RD) of the anterior thalamic radiation, cingulum, corticospinal tract, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, forceps major, forceps minor, superior longitudinal fasciculus, and uncinate fasciculus in children and adolescents with ADHD (n = 56), unaffected siblings of ADHD probands (n = 31), and healthy controls (n = 17). Results Subjects with ADHD showed significantly higher MD than controls in the anterior thalamic radiation, forceps minor, and superior longitudinal fasciculus. Unaffected siblings of subjects with ADHD displayed similar differences in MD as subjects with ADHD. Although none of the tested tracts showed a significant effect of FA, the tracts with elevated MD likewise displayed elevated AD both in subjects with ADHD and in unaffected siblings. Differences in RD between subjects with ADHD, unaffected siblings, and controls were not as widespread as differences in MD and AD. Conclusion Our findings suggest that disruptions in white matter microstructure occur in several large white matter pathways in association with ADHD and indicate a familial liability for the disorder. Furthermore, MD may reflect these abnormalities more sensitively than FA.
TL;DR: Using 64-direction DTI scanning in 27 participants with bipolar disorder (BD) and 26 age-and-gender-matched healthy control subjects, relative length, density, and fractional anisotrophy of WM tracts involved in emotion regulation or theorized to be important neural components in BD neuropathology are compared.
Abstract: With the introduction of diffusion tensor imaging (DTI), structural differences in white matter (WM) architecture between psychiatric populations and healthy controls can be systematically observed and measured. In particular, DTI-tractography can be used to assess WM characteristics over the entire extent of WM tracts and aggregated fiber bundles. Using 64-direction DTI scanning in 27 participants with bipolar disorder (BD) and 26 age-and-gender-matched healthy control subjects, we compared relative length, density, and fractional anisotrophy (FA) of WM tracts involved in emotion regulation or theorized to be important neural components in BD neuropathology. We interactively isolated 22 known white matter tracts using region-of-interest placement (TrackVis software program) and then computed relative tract length, density, and integrity. BD subjects demonstrated significantly shorter WM tracts in the genu, body and splenium of the corpus callosum compared to healthy controls. Additionally, bipolar subjects exhibited reduced fiber density in the genu and body of the corpus callosum, and in the inferior longitudinal fasciculus bilaterally. In the left uncinate fasciculus, however, BD subjects exhibited significantly greater fiber density than healthy controls. There were no significant differences between groups in WM tract FA for those tracts that began and ended in the brain. The significance of differences in tract length and fiber density in BD is discussed.
TL;DR: Altered white matter integrity in the superior and inferior longitudinal fasciculi and thalamic to frontal tracts may contribute to the behavioral characteristics of all of these disorders.
TL;DR: The data show that, at the group level, the md-aMCI subgroup has the most pronounced damage in white matter integrity, and individually, SVM analysis of white matter FA provided highly accurate classification of MCI subtypes.
Abstract: BACKGROUND AND PURPOSE: MCI was recently subdivided into sd-aMCI, sd-fMCI, and md-aMCI. The current investigation aimed to discriminate between MCI subtypes by using DTI. MATERIALS AND METHODS: Sixty-six prospective participants were included: 18 with sd-aMCI, 13 with sd-fMCI, and 35 with md-aMCI. Statistics included group comparisons using TBSS and individual classification using SVMs. RESULTS: The group-level analysis revealed a decrease in FA in md-aMCI versus sd-aMCI in an extensive bilateral, right-dominant network, and a more pronounced reduction of FA in md-aMCI compared with sd-fMCI in right inferior fronto-occipital fasciculus and inferior longitudinal fasciculus. The comparison between sd-fMCI and sd-aMCI, as well as the analysis of the other diffusion parameters, yielded no significant group differences. The individual-level SVM analysis provided discrimination between the MCI subtypes with accuracies around 97%. The major limitation is the relatively small number of cases of MCI. CONCLUSIONS: Our data show that, at the group level, the md-aMCI subgroup has the most pronounced damage in white matter integrity. Individually, SVM analysis of white matter FA provided highly accurate classification of MCI subtypes.
TL;DR: Results indicate that progressive pathological white matter alterations can be quantified using the DTI parameters utilized here and may prove to be a useful biological marker for monitoring the pathophysiological course of AD.
TL;DR: Evidence is provided that individual structural differences in the left IPS are associated with arithmetic scores in schoolchildren.
Abstract: Arithmetic skill is of critical importance for academic achievement, professional success and everyday life, and childhood is the key period to acquire this skill. Neuroimaging studies have identified that left parietal regions are a key neural substrate for representing arithmetic skill. Although the relationship between functional brain activity in left parietal regions and arithmetic skill has been studied in detail, it remains unclear about the relationship between arithmetic achievement and structural properties in left inferior parietal area in schoolchildren. The current study employed a combination of voxel-based morphometry (VBM) for high-resolution T1-weighted images and fiber tracking on diffusion tensor imaging (DTI) to examine the relationship between structural properties in the inferior parietal area and arithmetic achievement in 10-year-old schoolchildren. VBM of the T1-weighted images revealed that individual differences in arithmetic scores were significantly and positively correlated with the gray matter (GM) volume in the left intraparietal sulcus (IPS). Fiber tracking analysis revealed that the forceps major, left superior longitudinal fasciculus (SLF), bilateral inferior longitudinal fasciculus (ILF) and inferior fronto-occipital fasciculus (IFOF) were the primary pathways connecting the left IPS with other brain areas. Furthermore, the regression analysis of the probabilistic pathways revealed a significant and positive correlation between the fractional anisotropy (FA) values in the left SLF, ILF and bilateral IFOF and arithmetic scores. The brain structure-behavior correlation analyses indicated that the GM volumes in the left IPS and the FA values in the tract pathways connecting left IPS were both related to children's arithmetic achievement. The present findings provide evidence that individual structural differences in the left IPS are associated with arithmetic scores in schoolchildren.
TL;DR: The results indicated that the presence of white matter changes during the early stage of DAI may be helpful for predicting cognitive dysfunction over the long term.
Abstract: BACKGROUND White matter disruption is known to contribute to neurocognitive deficits after diffuse axonal injury (DAI). This study evaluated the relationship between white matter integrity using diffusion tensor imaging in the early stage and cognitions in the chronic stage. METHODS Diffusion tensor imaging was performed in 15 patients with DAI within 7 days of injury and in 15 patients in the control group. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated within regions of interest, including the posterior limb of the internal capsule, uncinate fasciculus (UF), anterior corona radiate (ACR), superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF), genu of the corpus callosum, body of the corpus callosum, and splenium of the corpus callosum and cingulum bundle (CB). The patients with DAI and the patients in the control group also underwent neuropsychological testing during the chronic stage after DAI. RESULTS The region-of-interest analysis showed significantly reduced FA and AD values in all nine regions within 7 days of injury as well as increased MD values in the corpus callosum among patients in the DAI group. The patients demonstrated significantly poorer performance on the working memory tests and attention test. In patients, working memory function was positively correlated with the AD value in the UF and with the FA value in the CB, UF, SLF, and ILF. Working memory function was inversely correlated with the RD value in the CB, SLF, and ILF and with the MD value in the SLF and ILF. In addition, the attention function demonstrated a positive correlation with the RD value in the ACR, SLF, and ILF and with the MD value in the ACR, SLF, and ILF. In addition, attention was inversely correlated with the FA values for the posterior limb of the internal capsule, ACR, SLF, and ILF. CONCLUSION The results indicated that the presence of white matter changes during the early stage of DAI may be helpful for predicting cognitive dysfunction over the long term. LEVEL OF EVIDENCE Prognostic study, level III.
TL;DR: The findings suggest that the FMR1 gene is a genetic factor common for both working memory and brain structure, and has implications for the understanding of the transmission of intelligence andbrain structure.
TL;DR: The intraoperative combination of tractography and DES contributed to maximum safe resection of gliomas located in language areas, and language functions were preserved in all patients.
Abstract: For gliomas, the goal of surgery is to maximise the extent of resection (EOR) while minimising the postoperative morbidity. The purpose of this study was to evaluate the benefits of a protocol developed for the surgical management of gliomas located in language areas, where tractography-integrated navigation was used in conjunction with direct electrical stimulations (DES). The authors included ten patients suffering of gliomas located in language areas. The preoperative planning for multimodal navigation was done by integrating anatomical magnetic resonance images and subcortical pathway volumes generated by diffusion tensor imaging. Six white matter fascicles implicated in language functions were reconstructed in each patient, including fibres for phonological processing (i.e. the arcuate fasciculus), fibres for lexical-semantic processing (i.e. the inferior frontooccipital fasciculus, inferior longitudinal fasciculus and uncinate fasciculus), and two premotor fasciculi involved in the preparation of speech movements (the subcallosal medialis fasciculus and cortical fibres originating from the medial and lateral premotor areas). During surgery, language fascicles were identified by direct visualisation on tractography-integrated navigation images and by observing transient language inhibition after subcortical DES. Language deficits were evaluated preoperatively and postoperatively, and compared with the EOR. Tractography was successfully performed in all patients, preoperatively demonstrating the relationships between the tumours to resect and the language fascicles to preserve from injury. With the use of the tractography-integrated navigation system and intraoperative DES, language functions were preserved in all patients. The mean volumetric resection was 93.0 ± 10.4 % of the preoperative tumour volume, with a gross total resection in 60 % of patients. The intraoperative combination of tractography and DES contributed to maximum safe resection of gliomas located in language areas.
TL;DR: Structural imaging techniques found that damage to the left extrasylvian regions, including the uncinate, inferior fronto-occipital fasciculus, and sagittal stratum, was significantly associated with impairments in access to orthographic word forms and semantics.
Abstract: We report patterns of dysgraphia in participants with primary progressive aphasia that can be explained by assuming disruption of one or more cognitive processes or representations in the complex process of spelling. These patterns are compared to those described in participants with focal lesions (stroke). Using structural imaging techniques, we found that damage to the left extrasylvian regions, including the uncinate, inferior fronto-occipital fasciculus, and sagittal stratum (including geniculostriate pathway and inferior longitudinal fasciculus), as well as other deep white and grey matter structures, was significantly associated with impairments in access to orthographic word forms and semantics (with reliance on phonology-to-orthography to produce a plausible spelling in the spelling to dictation task). These results contribute not only to our understanding of the patterns of dysgraphia following acquired brain damage but also the neural substrates underlying spelling.
TL;DR: It is concluded that reduced axonal changes may be key to understanding the underlying pathology of WM leading to the visuo-spatial phenotype in 22q11.2DS.
Abstract: Patients with 22q11.2 deletion syndrome (22q11.2DS) represent a population at high risk for developing schizophrenia, as well as learning disabilities. Deficits in visuo-spatial memory are thought to underlie some of the cognitive disabilities. Neuronal substrates of visuo-spatial memory include the inferior fronto-occipital fasciculus (IFOF) and the inferior longitudinal fasciculus (ILF), two tracts that comprise the ventral visual stream. Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) is an established method to evaluate white matter (WM) connections in vivo. DT-MRI scans of nine 22q11.2DS young adults and nine matched healthy subjects were acquired. Tractography of the IFOF and the ILF was performed. DT-MRI indices, including Fractional anisotropy (FA, measure of WM changes), axial diffusivity (AD, measure of axonal changes) and radial diffusivity (RD, measure of myelin changes) of each of the tracts and each group were measured and compared. The 22q11.2DS group showed statistically significant reductions of FA in IFOF in the left hemisphere. Additionally, reductions of AD were found in the IFOF and the ILF in both hemispheres. These findings might be the consequence of axonal changes, which is possibly due to fewer, thinner, or less organized fibers. No changes in RD were detected in any of the tracts delineated, which is in contrast to findings in schizophrenia patients where increases in RD are believed to be indicative of demyelination. We conclude that reduced axonal changes may be key to understanding the underlying pathology of WM leading to the visuo-spatial phenotype in 22q11.2DS.
TL;DR: As an objective and user-independent method, TBSS confirmed that preterm infants with impaired antenatal growth have impaired white matter maturation compared to pre term infants with normal antenatalgrowth.
Abstract: White matter maturation of infants can be studied using diffusion tensor imaging (DTI). DTI of the white matter of the infant brain provides the best available clinical measures of brain tissue organisation and integrity. The purpose of this study was to compare white matter maturation between preterm infants born small for gestational age (SGA) and preterms with weight appropriate for gestational age (AGA) at birth. A total of 36 preterm infants were enrolled in the study (SGA, n = 9). A rater-independent method called tract-based spatial statistics (TBSS) was used to assess white matter maturation. When measured by TBSS, the AGA infants showed higher fractional anisotrophy values in several white matter tracts than the SGA infants. Areas with significant differences included anterior thalamic radiation, corticospinal tract, forceps major and minor, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, superior longitudinal fasciculus, uncinate fasciculus, and superior longitudinal fasciculus (temporal part). No significant difference was found for mean diffusivity. As an objective and user-independent method, TBSS confirmed that preterm infants with impaired antenatal growth have impaired white matter maturation compared to preterm infants with normal antenatal growth. The differences were mainly detected in radiations that are myelinated first.
TL;DR: The inverse correlation of memory dysfunction score with FA of white matter tracts suggest that white matter deficit in these white matter fibers may contribute to underlying dysfunction in memory in alcoholism.
TL;DR: Widespread decrease in FA values in the patients compared with the controls suggests that the pathologic changes extend diffusely to most major white matter tracts, and the detection of DTI abnormality has an added value to lateralization.
TL;DR: To examine whether white matter hyperintensities on brain magnetic resonance imaging (MRI) in tracts in older adults with mobility impairment are linked to outcomes of gait rehabilitation interventions, a large number of studies have found WMHs to be positive on MRI in these patients.
Abstract: Objectives: To examine whether white matter hyperintensities (WMHs) on brain magnetic resonance imaging (MRI) in tracts in older adults with mobility impairment are linked to outcomes of gait rehabilitation interventions.
Design: Twelve-week randomized controlled single-blind trial.
Setting: University-based mobility research laboratory.
Participants: Ambulatory adults aged 65 and older with mobility impairment.
Intervention: A conventional gait intervention focusing on walking, endurance, balance, and strength (WEBS, n = 21) and a task-oriented intervention focused on timing and coordination of gait (TC, n = 23).
Measurements: Self-paced gait speed was measured over an instrumented walkway before and after the intervention, and WMH and brain volumes were quantified on preintervention brain MRI using an automated segmentation process. A white matter tract atlas was overlaid on the segmented images to measure tract WMH volumes, and WMH volumes were normalized to total brain volume. Aggregate WMH volumes in all white matter tracts and individual WMH volumes in specific longitudinal tracts (superior longitudinal fasciculus, inferior longitudinal fasciculus, and fronto-occipital fasciculus) and the cingulum were measured.
Results: Gait speed gains in the TC group were of the same magnitude, independent of WMH volume measures in all except the cingulum, but in the WEBS group, gain in gait speed was smaller with greater overall tract WMH volumes (P < .001) and with greater WMH volume in the three longitudinal tracts (P < .001 to .02).
Conclusion: Gains in gait speed with two types of gait rehabilitation are associated with individual differences in WMHs. Task-oriented therapy that targets timing and coordination of gait may particularly benefit older adults with WMHs in brain tracts that influence gait and cognition.
TL;DR: The Dejerines provided the first descriptions of the anatomical pillars of present-day language models (such as the SLF/AF) and their anatomical descriptions of fasciculi in aphasia patients provided a foundation for the modern concept of the dorsal and ventral streams in language processing.
TL;DR: Results suggest a relationship between impairments in insight, a clinically important phenotype, and fiber disorganization in tracts connecting visual with emotion/memory processing systems in body dysmorphic disorder.
Abstract: Body dysmorphic disorder (BDD) is characterized by an often-delusional preoccupation with misperceived defects of appearance, causing significant distress and disability. Although previous studies have found functional abnormalities in visual processing, frontostriatal, and limbic systems, no study to date has investigated the microstructure of white matter connecting these systems in BDD. Participants comprised 14 medication-free individuals with BDD and 16 healthy controls who were scanned using diffusion-weighted magnetic resonance imaging (MRI). We utilized probabilistic tractography to reconstruct tracts of interest, and tract-based spatial statistics to investigate whole brain white matter. To estimate white matter microstructure, we used fractional anisotropy (FA), mean diffusivity (MD), and linear and planar anisotropy (c(l) and c(p)). We correlated diffusion measures with clinical measures of symptom severity and poor insight/delusionality. Poor insight negatively correlated with FA and c(l) and positively correlated with MD in the inferior longitudinal fasciculus (ILF) and the forceps major (FM). FA and c(l) were lower in the ILF and the inferior fronto-occipital fasciculus and higher in the FM in the BDD group, but differences were nonsignificant. This is the first diffusion-weighted MR investigation of white matter in BDD. Results suggest a relationship between impairments in insight, a clinically important phenotype, and fiber disorganization in tracts connecting visual with emotion/memory processing systems.
TL;DR: The results suggest that the left ventral, AF and SLF-related pathways are closely related to visual, auditory and hand-related language function, respectively.
Abstract: The anatomic localization of brain functions can be characterized via diffusion tensor imaging in patients with brain tumors and neurological symptoms. The goal of the present study was to evaluate the function of the ventral, arcuate fasciculus (AF) and the superior longitudinal fasciculus (SLF)-related language pathways using these techniques by analyzing 9 patients treated in our hospital between 2007 and 2011. In cases 1-3, the left ventral pathways, namely, the inferior longitudinal fasciculus, uncinate fasciculus or inferior fronto-occipital fasciculus, were mainly damaged, and the common dysfunction experienced by these patients was a deficit in object naming. In cases 4-6, the left SLF was mainly damaged, and the common deficit was dysgraphia. In cases 7-9, the left AF was mainly damaged, and almost all language functions related to phonology were abnormal. These results suggest that the left ventral, AF and SLF-related pathways are closely related to visual, auditory and hand-related language function, respectively.