Mapping covariance in brain FDG uptake to structural connectivity

Abstract Purpose Inter-subject covariance of regional 18F-fluorodeoxyglucose (FDG) PET measures (FDGcov) as proxy of brain connectivity has been gaining an increasing acceptance in the community. Yet, it is still unclear to what extent FDGcov is underlied by actual structural connectivity via white matter fiber tracts. In this study, we quantified the degree of spatial overlap between FDGcov and structural connectivity networks. Methods We retrospectively analyzed neuroimaging data from 303 subjects, both patients with suspected neurodegenerative disorders and healthy individuals. For each subject, structural magnetic resonance, diffusion tensor imaging, and FDG-PET data were available. The images were spatially normalized to a standard space and segmented into 62 anatomical regions using a probabilistic atlas. Sparse inverse covariance estimation was employed to estimate FDGcov. Structural connectivity was measured by streamline tractography through fiber assignment by continuous tracking. Results For the whole brain, 55% of detected connections were found to be convergent, i.e., present in both FDGcov and structural networks. This metric for random networks was significantly lower, i.e., 12%. Convergent were 80% of intralobe connections and only 30% of interhemispheric interlobe connections. Conclusion Structural connectivity via white matter fiber tracts is a relevant substrate of FDGcov, underlying around a half of connections at the whole brain level. Short-range white matter tracts appear to be a major substrate of intralobe FDGcov connections.

Download Full-text

Integrative Structural Brain Network Analysis In Diffusion Tensor Imaging

10.1101/129015 ◽

2017 ◽

Cited By ~ 1

Author(s):

Moo K. Chung ◽

Jamie L. Hanson ◽

Nagesh Adluru ◽

Andrew L. Alexander ◽

Richard J. Davidson ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Diffusion Tensor ◽

Structural Connectivity ◽

Brain Regions ◽

Brain Network ◽

Node Degree ◽

Fiber Tracts ◽

White Matter Fiber Tracts ◽

Structural Brain Network ◽

Structural Networks

AbstractIn diffusion tensor imaging, structural connectivity between brain regions is often measured by the number of white matter fiber tracts connecting them. Other features such as the length of tracts or fractional anisotropy (FA) are also used in measuring the strength of connectivity. In this study, we investigated the effects of incorporating the number of tracts, the tract length and FA-values into the connectivity model. Using various node-degree based graph theory features, the three connectivity models are compared. The methods are applied in characterizing structural networks between normal controls and maltreated children, who experienced maltreatment while living in post-institutional settings before being adopted by families in the US.

Download Full-text

Motor cortex gliomas induces microstructural changes of large fiber tracts revealed by TBSS

Scientific Reports ◽

10.1038/s41598-020-73746-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Xiangdong Wang ◽

Chunyao Zhou ◽

Lei Wang ◽

Yinyan Wang ◽

Tao Jiang

Keyword(s):

White Matter ◽

Motor Cortex ◽

Diffusion Tensor ◽

Early Stage ◽

Mean Diffusivity ◽

Cerebral White Matter ◽

Control Group ◽

Fiber Tracts ◽

3.0 T ◽

White Matter Fiber Tracts

Abstract Gliomas grow and invade along white matter fiber tracts. This study assessed the effects of motor cortex gliomas on the cerebral white matter fiber bundle skeleton. The motor cortex glioma group included 21 patients, and the control group comprised 14 healthy volunteers. Both groups underwent magnetic resonance imaging-based 3.0 T diffusion tensor imaging. We used tract-based spatial statistics to analyze the characteristics of white matter fiber bundles. The left and right motor cortex glioma groups were analyzed separately from the control group. Results were statistically corrected by the family-wise error rate. Compared with the controls, patients with left motor cortex gliomas exhibited significantly reduced fractional anisotropy and an increased radial diffusivity in the corpus callosum. The alterations in mean diffusivity (MD) and the axial diffusivity (AD) were widely distributed throughout the brain. Furthermore, atlas-based analysis showed elevated MD and AD in the contralateral superior fronto-occipital fasciculus. Motor cortex gliomas significantly affect white matter fiber microstructure proximal to the tumor. The range of affected white matter fibers may extend beyond the tumor-affected area. These changes are primarily related to early stage tumor invasion.

Download Full-text

Diffusion tensor imaging study of white matter fiber tracts in adolescent attention-deficit/hyperactivity disorder

Psychiatry Research Neuroimaging ◽

10.1016/j.pscychresns.2012.11.008 ◽

2013 ◽

Vol 211 (2) ◽

pp. 186-187 ◽

Cited By ~ 23

Author(s):

Tzu-Chao Chuang ◽

Ming-Ting Wu ◽

Sheng-Po Huang ◽

Mei-Jui Weng ◽

Pinchen Yang

Keyword(s):

Attention Deficit Hyperactivity Disorder ◽

Diffusion Tensor Imaging ◽

White Matter ◽

Attention Deficit ◽

Diffusion Tensor ◽

Imaging Study ◽

Hyperactivity Disorder ◽

Fiber Tracts ◽

White Matter Fiber Tracts ◽

Diffusion Tensor Imaging Study

Download Full-text

Postshunting corpus callosum swelling with depiction on tractography

Journal of Neurosurgery Pediatrics ◽

10.3171/2012.10.peds1242 ◽

2013 ◽

Vol 11 (2) ◽

pp. 178-180 ◽

Cited By ~ 1

Author(s):

Daniel T. Ginat ◽

Sanjay P. Prabhu ◽

Joseph R. Madsen

Keyword(s):

Diffusion Tensor Imaging ◽

White Matter ◽

Corpus Callosum ◽

Posterior Margin ◽

Diffusion Tensor ◽

The Body ◽

Transverse Orientation ◽

Chronic Hydrocephalus ◽

Fiber Tracts ◽

White Matter Fiber Tracts

Alterations in the appearance of the corpus callosum occasionally occur following successful ventricular decompression in patients with chronic hydrocephalus. There are certain features on imaging that suggest the diagnosis of what the authors propose be termed “postshunting corpus callosum swelling,” including diffuse high T2 signal predominantly affecting the body of the corpus callosum, with transverse orientation along the crossing white matter tracts and scalloping along the posterior margin of the structure. In this report, the authors demonstrate preservation of the corpus callosum white matter fiber tracts by using diffusion tensor imaging with tractography.

Download Full-text

Diffusion tensor imaging correlates of hippocampal sclerosis and anterior temporal lobe T2 signal changes in pharmacoresistant epilepsy

International Journal of Epilepsy ◽

10.1016/j.ijep.2014.05.003 ◽

2014 ◽

Vol 01 (01) ◽

pp. 001-007 ◽

Cited By ~ 1

Author(s):

Kevin Spitler ◽

Francis Tirol ◽

Itzhak Fried ◽

Jerome Engel ◽

Noriko Salamon

Keyword(s):

Diffusion Tensor Imaging ◽

White Matter ◽

Temporal Lobe ◽

Diffusion Tensor ◽

Hippocampal Sclerosis ◽

Anterior Temporal Lobe ◽

Pharmacoresistant Epilepsy ◽

Fiber Tracts ◽

White Matter Fiber Tracts ◽

The Right

AbstractBackground and purpose Our goal was to determine fiber tract integrity in hippocampal sclerosis (HS) using diffusion tensor imaging (DTI) and to correlate white matter damage with other pathology in this disease.Methods Twenty-six patients and eight controls were studied with DTI tractography for 8 pairs of white matter fiber tracts and 2 commissural tracts. Fractional anisotropy (FA) of the fiber tracts was compared with controls. The FA of select fiber tracts was also compared with change in T2 signal in the anterior temporal lobe (ATC), and the performance on neuropsychological tests.Results In comparison with controls, subjects with left sided hippocampal sclerosis (L-HS) had 3 ipsilateral fiber tracts with decreased FA. The FA of fiber tracts was similar in right sided HS (R-HS) to controls. The ipsilateral inferior longitudinal fasciculus had a decrease in FA that correlated with the ATC (T2 signal change). The right superior longitudinal fasciculus had a decrease in FA proportional to lower performance on tests of memory and language.Conclusion The subjects with L-HS had more extensive structural abnormalities involving white matter tracts, both ipsilateral and contralateral. In contrast, subjects with R-HS had limited changes in white matter integrity. Pathology of white matter appears to be involved in deficits associated with HS, including ATC and cognitive performance.

Download Full-text

Effects of Lifelong Musicianship on White Matter Integrity and Cognitive Brain Reserve

Brain Sciences ◽

10.3390/brainsci11010067 ◽

2021 ◽

Vol 11 (1) ◽

pp. 67

Author(s):

Edna Andrews ◽

Cyrus Eierud ◽

David Banks ◽

Todd Harshbarger ◽

Andrew Michael ◽

...

Keyword(s):

White Matter ◽

Life Span ◽

Categorical Perception ◽

Diffusion Tensor ◽

Linear Regression Analysis ◽

Structural Connectivity ◽

Subcortical White Matter ◽

Brain Reserve ◽

Functional Changes ◽

Fiber Tracts

There is a significant body of research that has identified specific, high-end cognitive demand activities and lifestyles that may play a role in building cognitive brain reserve, including volume changes in gray matter and white matter, increased structural connectivity, and enhanced categorical perception. While normal aging produces trends of decreasing white matter (WM) integrity, research on cognitive brain reserve suggests that complex sensory–motor activities across the life span may slow down or reverse these trends. Previous research has focused on structural and functional changes to the human brain caused by training and experience in both linguistic (especially bilingualism) and musical domains. The current research uses diffusion tensor imaging to examine the integrity of subcortical white matter fiber tracts in lifelong musicians. Our analysis, using Tortoise and ICBM-81, reveals higher fractional anisotropy, an indicator of greater WM integrity, in aging musicians in bilateral superior longitudinal fasciculi and bilateral uncinate fasciculi. Statistical methods used include Fisher’s method and linear regression analysis. Another unique aspect of this study is the accompanying behavioral performance data for each participant. This is one of the first studies to look specifically at musicianship across the life span and its impact on bilateral WM integrity in aging.

Download Full-text

The missing role of gray matter in studying brain controllability

10.1101/2020.04.07.030015 ◽

2020 ◽

Author(s):

Hamidreza Jamalabadi ◽

Agnieszka Zuberer ◽

Vinod Jangir Kumar ◽

Meng Li ◽

Sarah Alizadeh ◽

...

Keyword(s):

White Matter ◽

Gray Matter ◽

Gray Matter Volume ◽

Structural Connectivity ◽

Matter Volume ◽

Fiber Tracts ◽

White Matter Fiber Tracts ◽

Structural Architecture ◽

Actual Energy Consumption ◽

Connectivity Strength

1AbstractBrain controllability properties are normally derived from the white matter fiber tracts in which the neural substrate of the actual energy consumption, namely the gray matter, has been widely ignored. Here, we study the relationship between gray matter volume of regions across the whole cortex and their respective control property derived from the structural architecture of the white matter fiber tracts. The data suggests that the ability of white fiber tracts to exhibit control at specific nodes not only depends on the connection strength of the structural connectome but additionally strongly depends on gray matter volume at the host nodes. Our data indicates that connectivity strength and gray matter volume interact with respect to the brain’s control properties, such that gray matter exerts the great impact in regions with high structural connectivity. Disentangling effects of the regional gray matter volume and connectivity strength, we found that frontal and sensory areas play crucial roles in controllability. Together these results suggest that structural and regional properties of the white matter and gray matter provide complementary information in studying the control properties of the intrinsic structural and functional architectural of the brain.

Download Full-text

Dorsal-to-ventral imbalance in the superior longitudinal fasciculus mediates methylphenidate’s effect on beta oscillations in ADHD

10.1101/2020.09.23.309526 ◽

2020 ◽

Author(s):

C. Mazzetti ◽

C. G. Damatac ◽

E. Sprooten ◽

N. ter Huurne ◽

J.K. Buitelaar ◽

...

Keyword(s):

White Matter ◽

Diffusion Tensor ◽

Structural Connectivity ◽

Superior Longitudinal Fasciculus ◽

Beta Oscillations ◽

Double Blind ◽

Attention Task ◽

White Matter Tracts ◽

Fiber Tracts ◽

Beta Power

AbstractBackgroundWhile pharmacological treatment with Methylphenidate (MPH) is a first line intervention for ADHD, its mechanisms of action have yet to be elucidated. In a previous MEG study, we demonstrated that MPH in ADHD normalizes beta depression in preparation to motor responses (1). We here seek to identify the white matter tracts that mediate MPH’s effect on beta oscillations.MethodsWe implemented a double-blind placebo-controlled crossover design, where boys diagnosed with ADHD underwent behavioral and MEG measurements during a spatial attention task while on and off MPH. Results were compared with an age/IQ-matched typically developing (TD) group performing the same task. Estimates of white matter tracts were obtained through diffusion tensor imaging (DTI). Based on aprioristic selection model criteria, we sought to determine the fiber tracts associated with electrophysiological, behavioral and clinical features of attentional functions.ResultsWe identified three main tracts: the anterior thalamic radiation (ATR), the Superior Longitudinal Fasciculus (‘parietal endings’) (SLFp) and Superior Longitudinal Fasciculus (‘temporal endings’) (SLFt). ADHD symptoms severity was associated with lower fractional anisotropy (FA) within the ATR. In addition, individuals with relatively higher FA in SLFp compared to SLFt showed faster and more accurate behavioral responses to MPH. Furthermore, the same parieto-temporal FA gradient explained the effects of MPH on beta modulation: subjects with ADHD exhibiting higher FA in SLFp compared to SLFt also displayed greater effects of MPH on beta power during response preparation.ConclusionsBased on MPH’s modulatory effects on striatal dopamine levels, our data suggest that the behavioral deficits and aberrant oscillatory modulations observed in ADHD depend on a structural connectivity imbalance within the SLF, caused by a diffusivity gradient in favor of temporal rather than parietal, fiber tracts.

Download Full-text

Enhanced White Matter Fiber Tracts in Advanced Jazz Improvisers

Brain Sciences ◽

10.3390/brainsci11040506 ◽

2021 ◽

Vol 11 (4) ◽

pp. 506

Author(s):

Kiran Dhakal ◽

Martin Norgaard ◽

Mukesh Dhamala

Keyword(s):

White Matter ◽

Imaging Study ◽

Human Cognition ◽

Functional Networks ◽

Fiber Tracts ◽

Neuronal Interactions ◽

Musical Improvisation ◽

White Matter Fiber Tracts ◽

Structural Networks ◽

And Behavior

Human cognition and behavior arise from neuronal interactions over brain structural networks. These neuronal interactions cause changes in structural networks over time. How a creative activity such as musical improvisation performance changes the brain structure is largely unknown. In this diffusion magnetic resonance imaging study, we examined the brain’s white matter fiber properties in previously identified functional networks and compared the findings between advanced jazz improvisers and non-musicians. We found that, for advanced improvisers compared with non-musicians, the normalized quantitative anisotropy (NQA) is elevated in the lateral prefrontal areas and supplementary motor area, and the underlying white matter fiber tracts connecting these areas. This enhancement of the diffusion anisotropy along the fiber pathway connecting the lateral prefrontal and supplementary motor is consistent with the functional networks during musical improvisation tasks performed by expert jazz improvisers. These findings together suggest that experts’ creative skill is associated with the task-relevant, long-timescale brain structural network changes, in support of related cognitive underpinnings.

Download Full-text