scholarly journals Left frontal white matter atrophy links to timing mechanisms relevant for apraxia of speech

2019 ◽  
Author(s):  
Rose Bruffaerts ◽  
Jolien Schaeverbeke ◽  
Manon Grube ◽  
Silvy Gabel ◽  
An-Sofie De Weer ◽  
...  
Keyword(s):  
White Matter ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Primary Progressive Aphasia ◽  
Speech Impairments ◽  
Apraxia Of Speech ◽  
Motor Speech ◽  
Left Frontal Lobe ◽  
Frontal White Matter ◽  
Perceptual Timing

AbstractObjectiveIn some patients with apraxia of speech (AOS), we observed impaired perceptual timing abilities, which lead us to propose a shared mechanism of impaired perceptual timing underlying impaired rhythm discrimination (perceptual processing) and AOS (motor speech output). Given that considerable white matter damage is often observed in these patients, we here investigate whether white matter changes are related to impaired rhythm processing as one possible mechanism underlying AOS.MethodsWe applied deformation-based morphometry (DBM) and diffusion tensor imaging (DTI) in 12 patients with the nonfluent variant (NFV) of Primary Progressive Aphasia (PPA) with AOS, as well as 11 patients with the semantic variant and 24 controls.ResultsSeventy-five percent of the patients with NFV displayed impaired rhythm processing and the severity of their impairment correlated with their degree of AOS. Moreover, left frontal white matter volume loss adjacent to the supplementary motor area (SMA) correlated with impaired rhythm processing. In addition, we obtained tract-based metrics of the left Aslant tract, which is typically damaged in NFV. The structural integrity of the left Aslant tract also correlated with rhythmic discrimination abilities in NFV.ConclusionsOur data suggest that a shared white matter substrate adjacent to the SMA contributes to impaired rhythm perception and motor speech impairments. This indicates that impaired perceptual timing may be one of the neurocomputational mechanisms underlying AOS. Our observation that regional variations in left frontal lobe atrophy are linked to the phenotypical heterogeneity in NFV may lead the way for earlier diagnosis.

Individual differences in white and grey matter structure associated with verbal habits of thought

2019 ◽  
Author(s):  
Justin C. Hayes ◽  
Katherine L Alfred ◽  
Rachel Pizzie ◽  
Joshua S. Cetron ◽  
David J. M. Kraemer
Keyword(s):  
Individual Differences ◽  
White Matter ◽  
Cognitive Processing ◽  
Grey Matter ◽  
Structural Changes ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Self Report ◽  
White Matter Tracts

Modality specific encoding habits account for a significant portion of individual differences reflected in functional activation during cognitive processing. Yet, little is known about how these habits of thought influence long-term structural changes in the brain. Traditionally, habits of thought have been assessed using self-report questionnaires such as the visualizer-verbalizer questionnaire. Here, rather than relying on subjective reports, we measured habits of thought using a novel behavioral task assessing attentional biases toward picture and word stimuli. Hypothesizing that verbal habits of thought are reflected in the structural integrity of white matter tracts and cortical regions of interest, we used diffusion tensor imaging and volumetric analyses to assess this prediction. Using a whole-brain approach, we show that word bias is associated with increased volume in several bilateral language regions, in both white and grey matter parcels. Additionally, connectivity within white matter tracts within an a priori speech production network increased as a function of word bias. These results demonstrate long-term structural and morphological differences associated with verbal habits of thought.

scholarly journals Frontal White Matter and Cingulum Diffusion Tensor Imaging Deficits in Alcoholism

2008 ◽  
Vol 32 (6) ◽  
pp. 1001-1013 ◽  
Author(s):  
Gordon J. Harris ◽  
Sharon Kim Jaffin ◽  
Steven M. Hodge ◽  
David Kennedy ◽  
Verne S. Caviness ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Diffusion Tensor ◽  
Frontal White Matter

scholarly journals Structural disconnectivity in schizophrenia: a diffusion tensor magnetic resonance imaging study

2003 ◽  
Vol 182 (5) ◽  
pp. 439-443 ◽  
Author(s):  
J. Burns ◽  
D. Job ◽  
M. E. Bastin ◽  
H. Whalley ◽  
T. Macgillivray ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Fractional Anisotropy ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Uncinate Fasciculus ◽  
Arcuate Fasciculus ◽  
Resonance Imaging ◽  
White Matter Tracts

BackgroundThere is growing evidence that schizophrenia is a disorder of cortical connectivity Specifically, frontotemporal and frontoparietal connections are thought to be functionally impaired. Diffusion tensor magnetic resonance imaging (DT–MRI) is a technique that has the potential to demonstrate structural disconnectivity in schizophrenia.AimsTo investigate the structural integrity of frontotemporal and frontoparietal white matter tracts in schizophrenia.MethodThirty patients with DSM–IV schizophrenia and thirty matched control subjects underwent DT–MRI and structural MRI. Fractional anisotropy – an index of the integrity of white matter tracts – was determined in the uncinate fasciculus, the anterior cingulum and the arcuate fasciculus and analysed using voxel-based morphometry.ResultsThere was reduced fractional anisotropy in the left uncinate fasciculus and left arcuate fasciculus in patients with schizophrenia compared with controls.ConclusionsThe findings of reduced white matter tract integrity in the left uncinate fasciculus and left arcuate fasciculus suggest that there is frontotemporal and frontoparietal structural disconnectivity in schizophrenia.

scholarly journals Microstructural integrity of corticospinal and medial lemniscus tracts: insights from diffusion tensor tractography of right-hand amputees

2019 ◽  
Vol 122 (1) ◽  
pp. 316-324 ◽  
Author(s):  
Huiling Peng ◽  
Carmen M. Cirstea ◽  
Christina L. Kaufman ◽  
Scott H. Frey
Keyword(s):  
White Matter ◽  
Upper Limb ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Medial Lemniscus ◽  
Residual Limb ◽  
Healthy Control ◽  
Continued Use ◽  
Microstructural Integrity ◽  
Activity Dependent

Reductions in sensory and motor activity following unilateral upper limb amputation during adulthood are associated with widespread, activity-dependent reorganization of the gray matter and white matter through the central nervous system. Likewise, in cases of congenital limb absence there is evidence that limited afferent or efferent activity affects the structural integrity of white matter pathways serving the affected side. Evidence that the structural integrity of mature sensory and motor tracts controlling the lost upper limb exhibits similar activity dependence is, however, sparse and inconsistent. Here we used diffusion tensor tractography to test whether amputation of the dominant right hand during adulthood ( n = 16) alters the microstructural integrity of the major sensory (medial lemniscus, ML) and motor (corticospinal tract, CST) pathways controlling missing hand function. Consistent with prior findings, healthy control subjects ( n = 27) exhibited higher fractional anisotropy (FA), an index of white matter microstructural integrity, within dominant left CST and nondominant right ML. Critically, in contrast to what might be expected if the microstructural organization of these tracts is activity dependent, these asymmetries persisted in amputees. Moreover, we failed to detect any differences in dominant left ML or CST between healthy control subjects and amputees. Our results are consistent with these white matter tracts being robust to changes in activity once mature or that continued use of the residual limb (in a compensatory fashion or with prosthesis) provides stimulation sufficient to maintain tract integrity. NEW & NOTEWORTHY We report that unilateral hand amputation in adults has no significant effects on the structure of major sensory or motor pathways contralateral to the amputation. Our results are consistent with the organization of these white matter tracts being robust to changes in activity once mature or that continued use of the residual limb (with or without a prosthesis) provides stimulation sufficient to maintain tract integrity.

Diffusion Tensor Imaging Reveals Supplementary Lesions to Frontal White Matter in Idiopathic Normal Pressure Hydrocephalus

Neurosurgery ◽  
2011 ◽  
Vol 68 (6) ◽  
pp. 1586-1593 ◽  
Author(s):  
Niklas Lenfeldt ◽  
Anne Larsson ◽  
Lars Nyberg ◽  
Richard Birgander ◽  
Anders Eklund ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Corpus Callosum ◽  
Normal Pressure Hydrocephalus ◽  
Diffusion Tensor ◽  
White Matter Lesions ◽  
Normal Pressure ◽  
Centrum Semiovale ◽  
Frontal White Matter ◽  
Before And After

Abstract BACKGROUND: Idiopathic normal-pressure hydrocephalus (INPH) is associated with white matter lesions, but the extent and severity of the lesions do not cohere with symptoms or improvement after shunting, implying the presence of further, yet undisclosed, injuries to white matter in INPH. OBJECTIVE: To apply diffusion tensor imaging (DTI) to explore white matter lesions in patients with INPH before and after drainage of cerebrospinal fluid (CSF). METHODS: Eighteen patients and 10 controls were included. DTI was performed in a 1.5T MRI scanner before and after 3-day drainage of 400 mL of CSF. Regions of interest included corpus callosum, capsula interna, frontal and lateral periventricular white matter, and centrum semiovale. White matter integrity was quantified by assessing fractional anisotropies (FA) and apparent diffusion coefficients (ADC), comparing them between patients and controls and between patients before and after drainage. The significance level corresponded to .05 (Bonferroni corrected). RESULTS: Decreased FA in patients was found in 3 regions (P < .002, P < .001, and P < .001) in anterior frontal white matter, whereas elevated ADC was found in genu corpus callosum (P < .001) and areas of centrum semiovale associated with the precentral gyri (P < .002). Diffusion patterns in these areas did not change after drainage. CONCLUSION: DTI reveals subtle injuries—interpreted as axonal loss and gliosis—to anterior frontal white matter where high-order motor systems between frontal cortex and basal ganglia travel, further supporting the notion that motor symptoms in INPH are caused by a chronic ischemia to the neuronal systems involved in the planning processes of movements.

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