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Matter Microstructure (matter + microstructure)

Distribution by Scientific Domains

Life Sciences	33%

Kinds of Matter Microstructure

white matter microstructure

Selected Abstracts

Characterization of White Matter Microstructure in Fetal Alcohol Spectrum Disorders

ALCOHOLISM, Issue 3 2009
Susanna L. Fryer
Background:, Exposure to alcohol during gestation is associated with CNS alterations, cognitive deficits, and behavior problems. This study investigated microstructural aspects of putative white matter abnormalities following prenatal alcohol exposure. Methods:, Diffusion tensor imaging was used to assess white matter microstructure in 27 youth (age range: 8 to 18 years) with (n = 15) and without (n = 12) histories of heavy prenatal alcohol exposure. Voxelwise analyses, corrected for multiple comparisons, compared fractional anisotropy (FA) and mean diffusivity (MD) between groups, throughout the cerebrum. Results:, Prenatal alcohol exposure was associated with low FA in multiple cerebral areas, including the body of the corpus callosum and white matter innervating bilateral medial frontal and occipital lobes. Fewer between-group differences in MD were observed. Conclusions:, These data provide an account of cerebral white matter microstructural integrity in fetal alcohol spectrum disorders and support extant literature showing that white matter is a target of alcohol teratogenesis. The white matter anomalies characterized in this study may relate to the neurobehavioral sequelae associated with gestational alcohol exposure, especially in areas of executive dysfunction and visual processing deficits. [source]

Intellectual abilities and white matter microstructure in development: A diffusion tensor imaging study

HUMAN BRAIN MAPPING, Issue 10 2010
Christian K. Tamnes
Abstract Higher-order cognitive functions are supported by distributed networks of multiple interconnected cortical and subcortical regions. Efficient cognitive processing depends on fast communication between these regions, so the integrity of the connections between them is of great importance. It is known that white matter (WM) development is a slow process, continuing into adulthood. While the significance of cortical maturation for intellectual development is described, less is known about the relationships between cognitive functions and maturation of WM connectivity. In this cross-sectional study, we investigated the associations between intellectual abilities and development of diffusion tensor imaging (DTI) derived measures of WM microstructure in 168 right-handed participants aged 8,30 years. Independently of age and sex, both verbal and performance abilities were positively related to fractional anisotropy (FA) and negatively related to mean diffusivity (MD) and radial diffusivity (RD), predominantly in the left hemisphere. Further, verbal, but not performance abilities, were associated with developmental differences in DTI indices in widespread regions in both hemispheres. Regional analyses showed relations with both FA and RD bilaterally in the anterior thalamic radiation and the cortico-spinal tract and in the right superior longitudinal fasciculus. In these regions, our results suggest that participants with high verbal abilities may show accelerated WM development in late childhood and a subsequent earlier developmental plateau, in contrast to a steadier and prolonged development in participants with average verbal abilities. Longitudinal data are needed to validate these interpretations. The results provide insight into the neurobiological underpinnings of intellectual development. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. [source]

Retrograde Wallerian degeneration of cranial corticospinal tracts in cervical spinal cord injury patients using diffusion tensor imaging

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 10 2008
Saurabh Guleria
Abstract Diffusion tensor imaging (DTI) has the potential to reveal disruption of white matter microstructure in chronically injured spinal cords. We quantified fractional anisotropy (FA) and mean diffusivity (MD) to demonstrate retrograde Wallerian degeneration (WD) of cranial corticospinal tract (CST) in cervical spinal cord injury (SCI). Twenty-two patients with complete cervical SCI in the chronic stage were studied with DTI along with 13 healthy controls. Mean FA and MD values were computed for midbrain, pons, medulla, posterior limb of internal capsule, and corona radiata. Significant reduction in the mean FA and increase in MD was observed in the cranial CST in patients with SCI compared with controls, suggesting retrograde WD. Statistically significant inverse FA and MD changes were noted in corona radiata, indicating some restoration of spared white matter tracts. Temporal changes in the DTI metrics suggest progressing degeneration in different regions of CST. These spatiotemporal changes in DTI metrics suggest continued WD in injured fibers along with simultaneous reorganization of spared white matter fibers, which may contribute to changing neurological status in chronic SCI patients. © 2008 Wiley-Liss, Inc. [source]

Delay Discounting Behavior and White Matter Microstructure Abnormalities in Youth With a Family History of Alcoholism

ALCOHOLISM, Issue 9 2010
Megan M. Herting
Background:, Youth with family history of alcohol abuse have a greater risk of developing an alcohol use disorder (AUD). Brain and behavior differences may underlie this increased vulnerability. The current study examined delay discounting behavior and white matter microstructure in youth at high risk for alcohol abuse, as determined by a family history of alcoholism (FH+), and youth without such family history (FH,). Methods:, Thirty-three healthy youth (FH+ = 15, FH, = 18), ages 11 to 15 years, completed a delay discounting task and underwent diffusion tensor imaging. Tract-based spatial statistics (Smith et al., 2006), as well as follow-up region-of-interest analyses, were performed to compare fractional anisotropy (FA) between FH+ and FH, youth. Results:, FH+ youth showed a trend toward increased discounting behavior and had significantly slower reaction times (RTs) on the delay discounting paradigm compared to FH, youth. Group differences in FA were seen in several white matter tracts. Furthermore, lower FA in the left inferior longitudinal fasciculus and the right optic radiation statistically mediated the relationship between FH status and slower RTs on the delay discounting task. Conclusions:, Youth with a family history of substance abuse have disrupted white matter microstructure, which likely contributes to less efficient cortical processing and may act as an intrinsic risk factor contributing to an increased susceptibility of developing AUD. In addition, FHP youth showed a trend toward greater impulsive decision making, possibly representing an inherent personal characteristic that may facilitate substance use onset and abuse in high-risk youth. [source]

Global,Local Interference is Related to Callosal Compromise in Alcoholism: A Behavior-DTI Association Study

ALCOHOLISM, Issue 3 2009
Eva M. Müller-Oehring
Background:, Visuospatial ability is a multifactorial process commonly impaired in chronic alcoholism. Identification of which features of visuospatial processing are affected and which are spared in alcoholism, however, has not been clearly determined. We used a global,local paradigm to assess component processes of visuospatial ability and MR diffusion tensor imaging (DTI) to examine whether alcoholism-related microstructural degradation of the corpus callosum contributes to disruption of selective lateralized visuospatial and attention processes. Methods:, A hierarchical letter paradigm was devised, where large global letters were composed of small local letters. The task required identification of target letters among distractors presented at global, local, both, or neither level. Attention was either selectively directed to global or local levels or divided between levels. Participants were 18 detoxified chronic alcoholics and 22 age-matched healthy controls. DTI provided quantitative assessment of the integrity of corpus callosal white matter microstructure. Results:, Alcoholics generally had longer reaction times than controls but obtained similar accuracy scores. Both groups processed local targets faster than global targets and showed interference from targets at the unattended level. Alcoholics exhibited moderate compromise in selectively attending to the global level when the global stimuli were composed of local targets. Such local interference was less with longer abstinence. Callosal microstructural integrity compromise predicted degree of interference from stimulus incongruency in the alcoholic group. This relationship was not observed for lateral or third ventricular volumes, which are measures of nonspecific cortical volume deficits. Conclusion:, Global,local feature perception was generally spared in abstinent chronic alcoholics, but impairments were observed when directing attention to global features and when global and local information interfered at stimulus or response levels. Furthermore, the interference-callosal integrity relationship in alcoholics indicates that compromised visuospatial functions include those requiring bilateral integration of information. [source]