scholarly journals Apparent thinning of visual cortex during childhood is associated with myelination, not pruning

2018 ◽  
Author(s):  
Vaidehi S. Natu ◽  
Jesse Gomez ◽  
Michael Barnett ◽  
Brianna Jeska ◽  
Evgeniya Kirilina ◽  
...  
Keyword(s):  
White Matter ◽  
Temporal Cortex ◽  
Mean Diffusivity ◽  
Tissue Growth ◽  
Childhood Development ◽  
Cortical Thinning ◽  
T1 Relaxation ◽  
Functional Development ◽  
Ventral Temporal Cortex ◽  
And Diffusion

AbstractMicrostructural mechanisms underlying apparent cortical thinning during childhood development are unknown. Using functional, quantitative, and diffusion magnetic resonance imaging in children and adults, we tested if tissue growth (lower T1 relaxation time and mean diffusivity (MD)) or pruning (higher T1 and MD) underlies cortical thinning in ventral temporal cortex (VTC). After age 5, T1 and MD decreased in mid and deep cortex of functionally-defined regions in lateral VTC, and in their adjacent white matter. T1 and MD decreases were (i) consistent with tissue growth related to myelin proliferation, which we verified with adult postmortem histology and (ii) correlated with apparent cortical thinning. Thus, contrary to prevailing theories, cortical tissue does not thin during childhood, it becomes more myelinated, shifting the gray-white matter boundary deeper into cortex. As tissue growth is prominent in regions with protracted functional development, our data suggest an intriguing hypothesis that functional development and myelination are interlinked.

scholarly journals Apparent thinning of human visual cortex during childhood is associated with myelination

2019 ◽  
Vol 116 (41) ◽  
pp. 20750-20759 ◽  
Author(s):  
Vaidehi S. Natu ◽  
Jesse Gomez ◽  
Michael Barnett ◽  
Brianna Jeska ◽  
Evgeniya Kirilina ◽  
...  
Keyword(s):  
White Matter ◽  
Temporal Cortex ◽  
Mean Diffusivity ◽  
Brain Regions ◽  
Tissue Growth ◽  
Quantitative Mri ◽  
Childhood Development ◽  
Cortical Thinning ◽  
Ventral Temporal Cortex

Human cortex appears to thin during childhood development. However, the underlying microstructural mechanisms are unknown. Using functional magnetic resonance imaging (fMRI), quantitative MRI (qMRI), and diffusion MRI (dMRI) in children and adults, we tested what quantitative changes occur to gray and white matter in ventral temporal cortex (VTC) from childhood to adulthood, and how these changes relate to cortical thinning. T1 relaxation time from qMRI and mean diffusivity (MD) from dMRI provide independent and complementary measurements of microstructural properties of gray and white matter tissue. In face- and character-selective regions in lateral VTC, T1 and MD decreased from age 5 to adulthood in mid and deep cortex, as well as in their adjacent white matter. T1 reduction also occurred longitudinally in children’s brain regions. T1 and MD decreases 1) were consistent with tissue growth related to myelination, which we verified with adult histological myelin stains, and 2) were correlated with apparent cortical thinning. In contrast, in place-selective cortex in medial VTC, we found no development of T1 or MD after age 5, and thickness was related to cortical morphology. These findings suggest that lateral VTC likely becomes more myelinated from childhood to adulthood, affecting the contrast of MR images and, in turn, the apparent gray–white boundary. These findings are important because they suggest that VTC does not thin during childhood but instead gets more myelinated. Our data have broad ramifications for understanding both typical and atypical brain development using advanced in vivo quantitative measurements and clinical conditions implicating myelin.

scholarly journals Cortical Thickness and Diffusion Properties in the Injured Brain: The Influence of Chronic Health Complaints

2020 ◽  
Vol 185 (Supplement_1) ◽  
pp. 168-175
Author(s):  
Maheen M Adamson ◽  
Keith L Main ◽  
Anna-Clare Milazzo ◽  
Salil Soman ◽  
Jennifer Kong ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
White Matter ◽  
Cortical Thickness ◽  
Mean Diffusivity ◽  
Self Report ◽  
Control Group ◽  
Cortical Thinning ◽  
And Diffusion ◽  
Diffusion Properties

ABSTRACT Introduction Cortical thickness and diffusion properties can be served as an indicator of aging and other brain changes such as those related to brain injury. It can additionally provide another platform by which we can characterize the injury and its associated symptoms, especially in the chronic condition. Methods We examined the changes in cortical thickness and diffusion properties in white matter tracts in 51 patients with and without traumatic brain injury (TBI) and/or self-report chronic symptoms. Results Significant cortical thinning was observed in the frontal lobe and temporal lobe for TBI patients with chronic symptoms, but not for TBI patients without chronic symptoms, compared with control group. Significant reduction in fractional anisotropy occurred on average across left and right major fiber tracts for TBI patients with chronic symptoms. No mean diffusivity changes were found in any individual white matter tract for TBI patients with or without chronic symptoms. Conclusions Traumatic brain injury patients with chronic symptoms have more significant cortical thinning or degeneration of diffusion properties than the mild to severe TBI patients without chronic symptoms. This finding suggests that symptom reporting should be assessed in line with objective measures in clinical practice.

scholarly journals White matter fascicles and cortical microstructure predict reading-related responses in human ventral temporal cortex

2020 ◽  
Author(s):  
Mareike Grotheer ◽  
Jason Yeatman ◽  
Kalanit Grill-Spector
Keyword(s):  
White Matter ◽  
Gray Matter ◽  
Linear Models ◽  
Temporal Cortex ◽  
Spatial Relationship ◽  
Spatial Layout ◽  
Proton Relaxation ◽  
Imaging Data ◽  
Data Driven Approach ◽  
Ventral Temporal Cortex

AbstractReading-related responses in the lateral ventral temporal cortex (VTC) show a consistent spatial layout across individuals, which is puzzling, since reading skills are acquired during childhood. Here, we tested the hypothesis that white matter fascicles and gray matter microstructure predict the location of reading-related responses in lateral VTC. We obtained functional (fMRI), diffusion (dMRI), and quantitative (qMRI) magnetic resonance imaging data in 30 adults. fMRI was used to map reading-related responses by contrasting responses in a reading task with those in adding and color tasks; dMRI was used to identify the brain’s fascicles and to map their endpoints density in lateral VTC; qMRI was used to measure proton relaxation time (T1), which depends on cortical tissue microstructure. We fit linear models that predict reading-related responses in lateral VTC from endpoint density and T1 and used leave-one-subject-out cross-validation to assess prediction accuracy. Using a subset of our participants (N=10, feature selection set), we find that i) endpoint density of the arcuate fasciculus (AF), inferior longitudinal fasciculus (ILF), and vertical occipital fasciculus (VOF) are significant predictors of reading-related responses, and ii) cortical T1 of lateral VTC further improves the predictions of the fascicle model. Next, in the remaining 20 participants (validation set), we showed that a linear model that includes T1, AF, ILF and VOF significantly predicts i) the map of reading-related responses across lateral VTC and ii) the location of the visual word form area, a region critical for reading. Overall, our data-driven approach reveals that the AF, ILF, VOF and cortical microstructure have a consistent spatial relationship with an individual’s reading-related responses in lateral VTC.HighlightsThe ILF, AF, and VOF predict the spatial layout of reading-related responses in VTCGray matter microstructure improves the prediction of reading-related responsesFascicles and gray matter structure together predict the location of the VWFA

scholarly journals Functionally Defined White Matter Reveals Segregated Pathways in Human Ventral Temporal Cortex Associated with Category-Specific Processing

Neuron ◽  
2015 ◽  
Vol 85 (1) ◽  
pp. 216-227 ◽  
Author(s):  
Jesse Gomez ◽  
Franco Pestilli ◽  
Nathan Witthoft ◽  
Golijeh Golarai ◽  
Alina Liberman ◽  
...  
Keyword(s):  
White Matter ◽  
Temporal Cortex ◽  
Ventral Temporal Cortex

scholarly journals Increased hippocampal-inferior temporal cortex white matter connectivity following donepezil treatment in patients with mild cognitive impairment: A diffusion tensor probabilistic tractography study

2021 ◽  
Author(s):  
Gwang-Won Kim ◽  
Kwangsung Park ◽  
Gwang-Woo Jeong
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
White Matter ◽  
Diffusion Tensor ◽  
Early Stage ◽  
Structural Connectivity ◽  
Temporal Cortex ◽  
Mean Diffusivity ◽  
Inferior Temporal Cortex ◽  
Probabilistic Tractography

Abstract The incidence of Alzheimer’s disease (AD) has been increasing each year; however, few methods are available to identify the effects of treatment for AD. Defective hippocampus has been associated with mild cognitive impairment (MCI), an early stage of AD. However, the effect of donepezil treatment on hippocampus-related networks is unknown. The purpose of this study was to evaluate the hippocampal white matter (WM) connectivity following donepezil treatment in patients with MCI using probabilistic tractography, and to further determine the WM integrity and changes in brain volume. Magnetic resonance imaging and diffusion tensor imaging (DTI) data of patients with MCI before and after 6-month donepezil treatment were acquired. Volumes and DTI scalars of 11 regions of interest comprising the frontal and temporal cortices and subcortical regions were measured. Seed-based structural connectivity analyses were focused on the hippocampus. Compared with healthy controls, patients with MCI showed significantly decreased hippocampal volume and WM connectivity with the superior frontal gyrus, as well as increased mean diffusivity (MD) and radial diffusivity (RD) in the amygdala (p < 0.05, Bonferroni-corrected). After six months of donepezil treatment, patients with MCI showed increased hippocampal-inferior temporal gyrus (ITG) WM connectivity (p < 0.05, Bonferroni-corrected), which was normalized to the healthy control. These findings will be useful in developing theories to describe the etiology of MCI and the therapeutic role of anticholinesterases.

scholarly journals The Interplay Between Gray Matter and White Matter Neurodegeneration in Subjective Cognitive Decline

2020 ◽  
Author(s):  
Nira Cedres ◽  
Patricia Diaz-Galvan ◽  
Lucio Diaz-Flores ◽  
J-Sebastian Muehlboeck ◽  
Yaiza Molina ◽  
...  
Keyword(s):  
White Matter ◽  
Cognitive Decline ◽  
Gray Matter ◽  
Mean Diffusivity ◽  
Occipital Lobe ◽  
Hippocampal Volume ◽  
Subjective Cognitive Decline ◽  
Community Based ◽  
Cortical Thinning ◽  
Behavioral Marker

Abstract AIMS: To investigate the interplay between gray matter (GM) and white matter (WM) neurodegeneration in subjective cognitive decline (SCD), including thickness across the whole cortical mantle, hippocampal volume, and integrity across the whole WM. METHODS: We included 225 cognitively unimpaired individuals from a community-based cohort, of whom 123 endorsed one or more subjective cognitive complaints. GM neurodegeneration was assessed through measures of cortical thickness across the whole mantle and hippocampal volume. WM neurodegeneration was assessed through measures of mean diffusivity (MD) across the whole WM skeleton. Mediation analysis and multiple linear regression were conducted to investigate the interplay between the measures of GM and WM neurodegeneration.RESULTS: A higher number of complaints was associated with reduced hippocampal volume, cortical thinning in several frontal and temporal areas and the insula, and higher MD across the WM skeleton, with a tendency to spare the occipital lobe. SCD-related cortical thinning and increased MD were associated with each other and jointly contributed to the complaints, but the contribution of cortical thinning to SCD was stronger.CONCLUSIONS: Neurodegeneration processes affecting the GM and WM seem to be associated with each other in SCD and include brain areas other than those typically targeted by Alzheimer’s disease (AD). Our findings suggest that SCD may be a sensitive behavioral marker of heterogeneous brain pathologies in individuals recruited from the community.

scholarly journals Late-life depression accentuates cognitive weaknesses in older adults with small vessel disease

2021 ◽  
Author(s):  
Lauren E. Oberlin ◽  
Matteo Respino ◽  
Lindsay Victoria ◽  
Lila Abreu ◽  
Matthew J. Hoptman ◽  
...  
Keyword(s):  
Older Adults ◽  
White Matter ◽  
Small Vessel Disease ◽  
Mean Diffusivity ◽  
Vascular Pathology ◽  
Late Life Depression ◽  
Older Adulthood ◽  
Vessel Disease ◽  
The Relationship ◽  
And Diffusion

AbstractNeuroimaging features of small vessel disease (SVD) are highly prevalent in older adulthood and associated with significant variability in clinical symptoms, yet the factors predicting these symptom disparities are poorly understood. We employed a novel metric of SVD, peak width of skeletonized mean diffusivity (PSMD), to elucidate the relationship of late-life depression (LLD) to the cognitive presentation of vascular pathology. A total of 109 older adults without a diagnosis of a neurocognitive disorder were enrolled in the study; 44 with major depressive disorder and 65 age-matched controls. Subjects completed neuropsychological testing and magnetic resonance imaging including FLAIR and diffusion tensor imaging sequences, from which white matter hyperintensity volume and diffusion metrics (fractional anisotropy, mean diffusivity, PSMD) were quantified. In hierarchical models, the relationship between vascular burden and cognitive performance varied as a function of diagnostic status, such that the negative association between PSMD and processing speed was significantly stronger in participants with LLD compared to controls. Greater PSMD also predicted poorer performance on delayed memory and executive function tasks specifically among those with LLD, while there were no associations between PSMD and task performance among controls. PSMD outperformed conventional SVD and diffusion markers in predicting cognitive performance and dysexecutive behaviors in participants with LLD. These data suggest that LLD may confer a vulnerability to the cognitive manifestations of white matter abnormalities in older adulthood. PSMD, a novel biomarker of diffuse microstructural changes in SVD, may be a more sensitive marker of subtle cognitive deficits stemming from vascular pathology in LLD.

scholarly journals Longitudinal Structural and Diffusion Weighted Neuroimaging of Young Children Born Preterm

2021 ◽  
Author(s):  
Julia Anna Adrian ◽  
Carolyn Sawyer ◽  
Roger Bakeman ◽  
Frank Haist ◽  
Natacha Akshoomoff
Keyword(s):  
Preterm Birth ◽  
Brain Injury ◽  
White Matter ◽  
Young Children ◽  
Brain Development ◽  
Mean Diffusivity ◽  
Full Term ◽  
Developmental Trajectory ◽  
Diffusion Weighted ◽  
And Diffusion

Children born preterm are at risk for diffuse injury to subcortical gray and white matter. This study’s objective was to examine structural brain development of young children born preterm. Participants were 47 children born preterm (less than 33 weeks gestational age) and 28 children born full-term. None of the children born preterm had significant brain injury. Children received structural and diffusion weighted MRI scans at 5, 6, and 7 years of age. The effect of preterm birth on volume of subcortical gray matter, and volume, fractional anisotropy (FA) and mean diffusivity (MD) of white matter tracts was examined via general linear models. Volumes of thalamus, brain stem, cerebellar white matter, and several cerebral fiber tracts were smaller, and ventricles were larger in children born preterm compared to full-term controls. We found no significant effect of preterm birth on diffusivity measures. Despite developmental changes and growth, group differences were present and similarly strong at all three ages. Even in the absence of significant neonatal brain injury, preterm birth has a persistent impact on early brain development. The lack of a significant birth status by age interaction suggests a delayed developmental trajectory.

scholarly journals Cortical recycling in high-level visual cortex during childhood development

2020 ◽  
Author(s):  
Marisa Nordt ◽  
Jesse Gomez ◽  
Vaidehi Natu ◽  
Alex A. Rezai ◽  
Dawn Finzi ◽  
...  
Keyword(s):  
Temporal Cortex ◽  
Childhood Development ◽  
School Age Children ◽  
School Age ◽  
Cortical Function ◽  
Longitudinal Development ◽  
Face Selectivity ◽  
Ventral Temporal Cortex ◽  
High Level ◽  
Atypical Brain Development

AbstractHuman ventral temporal cortex (VTC) contains category-selective regions that respond preferentially to ecologically-relevant categories such as faces, bodies, places, and words, which are causally involved in the perception of these categories. How do these regions develop during childhood? We used functional MRI to measure longitudinal development of category-selectivity in school-age children over 1 to 5 years. We discovered that from young childhood to the teens, face- and word-selective regions in VTC expand and become more category-selective, but limb-selective regions shrink and lose their preference for limbs. Critically, as a child develops, increases in face- and word-selectivity are directly linked to decreases in limb-selectivity, revealing that during childhood limb-selectivity in VTC is repurposed into word- and face-selectivity. These data provide evidence for cortical recycling during childhood development. This has important implications for understanding typical as well as atypical brain development and necessitates a rethinking of how cortical function develops during childhood.

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