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https://www.readbyqxmd.com/read/29454104/functional-brain-connectivity-is-predictable-from-anatomic-network-s-laplacian-eigen-structure
#1
Farras Abdelnour, Michael Dayan, Orrin Devinsky, Thomas Thesen, Ashish Raj
How structural connectivity (SC) gives rise to functional connectivity (FC) is not fully understood. Here we mathematically derive a simple relationship between SC measured from diffusion tensor imaging, and FC from resting state fMRI. We establish that SC and FC are related via (structural) Laplacian spectra, whereby FC and SC share eigenvectors and their eigenvalues are exponentially related. This gives, for the first time, a simple and analytical relationship between the graph spectra of structural and functional networks...
February 14, 2018: NeuroImage
https://www.readbyqxmd.com/read/29453244/white-matter-change-with-apathy-and-impulsivity-in-frontotemporal-lobar-degeneration-syndromes
#2
Claire J Lansdall, Ian T S Coyle-Gilchrist, P Simon Jones, Patricia Vázquez Rodríguez, Alicia Wilcox, Eileen Wehmann, Katrina M Dick, Trevor W Robbins, James B Rowe
OBJECTIVE: To identify the white matter correlates of apathy and impulsivity in the major syndromes associated with frontotemporal lobar degeneration, using diffusion-weighted imaging and data from the PiPPIN (Pick's Disease and Progressive Supranuclear Palsy: Prevalence and Incidence) study. We included behavioral and language variants of frontotemporal dementia, corticobasal syndrome, and progressive supranuclear palsy. METHODS: Seventy patients and 30 controls underwent diffusion tensor imaging at 3-tesla after detailed assessment of apathy and impulsivity...
February 16, 2018: Neurology
https://www.readbyqxmd.com/read/29448399/probabilistic-low-rank-factorization-accelerates-tensor-network-simulations-of-critical-quantum-many-body-ground-states
#3
Lucas Kohn, Ferdinand Tschirsich, Maximilian Keck, Martin B Plenio, Dario Tamascelli, Simone Montangero
We provide evidence that randomized low-rank factorization is a powerful tool for the determination of the ground-state properties of low-dimensional lattice Hamiltonians through tensor network techniques. In particular, we show that randomized matrix factorization outperforms truncated singular value decomposition based on state-of-the-art deterministic routines in time-evolving block decimation (TEBD)- and density matrix renormalization group (DMRG)-style simulations, even when the system under study gets close to a phase transition: We report linear speedups in the bond or local dimension of up to 24 times in quasi-two-dimensional cylindrical systems...
January 2018: Physical Review. E
https://www.readbyqxmd.com/read/29417492/quantitative-susceptibility-mapping-as-a-biomarker-for-evaluating-white-matter-alterations-in-parkinson-s-disease
#4
Xiaojun Guan, Peiyu Huang, Qiaoling Zeng, Chunlei Liu, Hongjiang Wei, Min Xuan, Quanquan Gu, Xiaojun Xu, Nian Wang, Xinfeng Yu, Xiao Luo, Minming Zhang
Myelinated white matter showing diamagnetic susceptibility is important for information transfer in the brain. In Parkinson's disease (PD), the white matter is also suffering degenerative alterations. Quantitative susceptibility mapping (QSM) is a novel technique for noninvasive assessment of regional white matter ultrastructure, and provides different information of white matter in addition to standard diffusion tensor imaging (DTI). In this study, we used QSM to detect spatial white matter alterations in PD patients (n = 65) and age- and sex-matched normal controls (n = 46)...
February 7, 2018: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/29408589/identification-of-stria-medullaris-fibers-in-the-massa-intermedia-using-diffusion-tensor-imaging
#5
Ryan B Kochanski, Robert Dawe, Mehmet Kocak, Sepehr Sani
BACKGROUND: The massa intermedia (MI) or interthalamic adhesion is an inconsistent band spanning between bilateral medial thalami that is absent in up to 20-30% of individuals. Little is known of its significance, especially in regards to functional pathways. Probabilistic diffusion tensor imaging (DTI) has recently been used to seed the lateral habenula (LHb) and define its afferent white matter pathway, the stria medullaris thalami (SM). We sought to determine if the MI serves as a conduit for crossing of limbic fibers such as the SM...
January 31, 2018: World Neurosurgery
https://www.readbyqxmd.com/read/29400493/einstein-equations-from-varying-complexity
#6
Bartłomiej Czech
A recent proposal equates the circuit complexity of a quantum gravity state with the gravitational action of a certain patch of spacetime. Since Einstein's equations follow from varying the action, it should be possible to derive them by varying complexity. I present such a derivation for vacuum solutions of pure Einstein gravity in three-dimensional asymptotically anti-de Sitter space. The argument relies on known facts about holography and on properties of tensor network renormalization, an algorithm for coarse-graining (and optimizing) tensor networks...
January 19, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29395749/reduced-white-matter-connectivity-associated-with-auditory-verbal-hallucinations-in-first-episode-and-chronic-schizophrenia-a-diffusion-tensor-imaging-study
#7
Xiaoling Zhang, Jie Gao, Feng Zhu, Wei Wang, Yajuan Fan, Qingyan Ma, Xiancang Ma, Jian Yang
This study aims to explore whether auditory verbal hallucinations (AVH) in schizophrenia are associated with the white matter abnormalities in tracts connecting language, auditory and memory/limbic networks in first-episode and chronic schizophrenia patients. 21 first-episode (FE-AVH) and 12 chronic (chronic-AVH group) patients who suffered from auditory verbal hallucinations and 26 healthy controls (HC group) were enrolled. Diffusion tensor imaging with tract-based spatial statistics was performed to assess the white matter changes between the two patient groups and HC group...
January 25, 2018: Psychiatry Research
https://www.readbyqxmd.com/read/29389126/quasi-2d-heisenberg-antiferromagnets-cux-pyz-2-bf4-with-x-cl-and-br
#8
Mariusz Kubus, Arianna Lanza, Rebecca Scatena, Leonardo H R Dos Santos, Björn Wehinger, Nicola Casati, Christoph Fiolka, Lukas Keller, Piero Macchi, Christian Rüegg, Karl W Krämer
Two Cu2+ coordination polymers [CuCl(pyz)2](BF4) 1 and [CuBr(pyz)2](BF4) 2 (pyz = pyrazine) were synthesized in the family of quasi two-dimensional (2D) [Cu(pyz)2]2+ magnetic networks. The layer connectivity by monatomic halide ligands results in significantly shorter interlayer distances. Structures were determined by single-crystal X-ray diffraction. Temperature-dependent X-ray diffraction of 1 revealed rigid [Cu(pyz)2]2+ layers that do not expand between 5 K and room temperature, whereas the expansion along the c-axis amounts to 2%...
February 1, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29374846/structural-and-functional-papez-circuit-integrity-in-amyotrophic-lateral-sclerosis
#9
Ana Paula Arantes Bueno, Walter Hugo L Pinaya, Luciana M Moura, Maxime Bertoux, Ratko Radakovic, Matthew C Kiernan, Antonio Lucio Teixeira, Leonardo Cruz de Souza, Michael Hornberger, João Ricardo Sato
Cognitive impairment in amyotrophic lateral sclerosis (ALS) is heterogeneous but now recognized as a feature in non-demented patients and no longer exclusively attributed to executive dysfunction. However, despite common reports of temporal lobe changes and memory deficits in ALS, episodic memory has been less explored. In the current study, we examined how the Papez circuit-a circuit known to participate in memory processes-is structurally and functionally affected in ALS patients (n = 20) compared with healthy controls (n = 15), and whether these changes correlated with a commonly used clinical measure of episodic memory...
January 27, 2018: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/29367447/unraveling-als-due-to-sod1-mutation-through-the-combination-of-brain-and-cervical-cord-mri
#10
Federica Agosta, Edoardo Gioele Spinelli, Ivan V Marjanovic, Zorica Stevic, Elisabetta Pagani, Paola Valsasina, Biljana Salak-Djokic, Milena Jankovic, Dragana Lavrnic, Vladimir S Kostic, Massimo Filippi
OBJECTIVE: To explore structural and functional changes of the brain and cervical cord in patients with amyotrophic lateral sclerosis (ALS) due to mutation in the superoxide dismutase (SOD1) gene compared with sporadic ALS. METHODS: Twenty patients with SOD1 ALS, 11 with sporadic ALS, and 33 healthy controls underwent clinical evaluation and brain MRI. Cortical thickness analysis, diffusion tensor MRI of the corticospinal tracts (CST) and corpus callosum, and resting-state functional connectivity were performed...
January 24, 2018: Neurology
https://www.readbyqxmd.com/read/29362992/white-matter-integrity-correlates-with-residual-consciousness-in-patients-with-severe-brain-injury
#11
Lubin Wang, Yi Yang, Shanshan Chen, Mingmei Ge, Jianghong He, Zheng Yang, Pan Lin, Xinhuai Wu
Previous studies have suggested that white matter disruption plays an important role in disorders of consciousness (DOC) after severe brain injury. Nevertheless, the integrity of white matter architecture supporting consciousness and its relations with clinical severity in patients with DOC remain to be established. In this study, diffusion tensor imaging (DTI) data was collected from 14 DOC patients and 15 healthy control subjects. We combined tract-based spatial statistics (TBSS) with region of interest (ROI) analysis to examine differences of DTI metrics on white matter skeletons between DOC patients and healthy controls, and the association between white matter integrity and patients' residual consciousness assessed by Coma Recovery Scale-Revised (CRS-R)...
January 23, 2018: Brain Imaging and Behavior
https://www.readbyqxmd.com/read/29357675/stuck-in-a-state-of-inattention-functional-hyperconnectivity-as-an-indicator-of-disturbed-intrinsic-brain-dynamics-in-adolescents-with-concussion-a-pilot-study
#12
Angela M Muller, Naznin Virji-Babul
Sports-related concussion in youth is a major public health issue. Evaluating the diffuse and often subtle changes in structure and function that occur in the brain, particularly in this population, remains a significant challenge. The goal of this pilot study was to evaluate the relationship between the intrinsic dynamics of the brain using resting-state functional magnetic resonance imaging (rs-fMRI) and relate these findings to structural brain correlates from diffusion tensor imaging in a group of adolescents with sports-related concussions ( n = 6) and a group of healthy adolescent athletes ( n = 6)...
January 2018: ASN Neuro
https://www.readbyqxmd.com/read/29354585/neuroanatomical-mechanism-of-cerebellar-mutism-after-stroke
#13
Sekwang Lee, Yoon Hye Na, Hyun Im Moon, Woo Suk Tae, Sung-Bom Pyun
Cerebellar mutism (CM) is a rare neurological condition characterized by lack of speech due to cerebellar lesions. CM is often reported in children. We describe a rare case of CM after spontaneous cerebellar hemorrhage. The patient showed mutism, irritability, decreased spontaneous movements and oropharyngeal apraxia. Diffusion tensor imaging revealed significant volume reduction of medial frontal projection fibers from the corpus callosum. In Tracts Constrained by UnderLying Anatomy (TRACULA) analysis, forceps major and minor and bilateral cingulum-angular bundles were not visualized...
December 2017: Annals of Rehabilitation Medicine
https://www.readbyqxmd.com/read/29353280/microstructure-of-strategic-white-matter-tracts-and-cognition-in-memory-clinic-patients-with-vascular-brain-injury
#14
J Matthijs Biesbroek, Alexander Leemans, Hanna den Bakker, Marco Duering, Benno Gesierich, Huiberdina L Koek, Esther van den Berg, Albert Postma, Geert Jan Biessels
BACKGROUND: White matter injury is an important factor for cognitive impairment in memory clinic patients. We determined the added value of diffusion tensor imaging (DTI) of strategic white matter tracts in explaining variance in cognition in memory clinic patients with vascular brain injury. METHODS: We included 159 patients. Conventional MRI markers (white matter hyperintensity volume, lacunes, nonlacunar infarcts, brain atrophy, and microbleeds), and fractional anisotropy and mean diffusivity (MD) of the whole brain white matter and of 18 white matter tracts were related to cognition using linear regression and Bayesian network analysis...
January 19, 2018: Dementia and Geriatric Cognitive Disorders
https://www.readbyqxmd.com/read/29347868/differential-white-matter-regional-alterations-in-motor-subtypes-of-early-drug-naive-parkinson-s-disease-patients
#15
Ming-Ching Wen, Hannah S E Heng, Zhonghao Lu, Zheyu Xu, Ling Ling Chan, Eng King Tan, Louis C S Tan
BACKGROUND: Parkinson's disease (PD) can be classified into tremor dominant (TD) and postural instability and gait difficulty (PIGD) subtypes with TD considered as the benign subtype. The neural alterations of the 2 subtypes in the early stages before administration of medications remain elusive. OBJECTIVE: This study assessed the subtype-related white matter (WM) microstructural features in newly diagnosed and drug-naive PD patients from the Parkinson's Progression Markers Initiative (PPMI)...
January 1, 2018: Neurorehabilitation and Neural Repair
https://www.readbyqxmd.com/read/29344935/progressive-topological-disorganization-of-brain-network-in-focal-epilepsy
#16
K M Park, B I Lee, K J Shin, S Y Ha, J Park, T H Kim, C W Mun, S E Kim
OBJECTIVE: Increasing evidence has suggested that epilepsy is a network disease. Graph theory is a mathematical tool that allows for the analysis and quantification of the brain network. We aimed to evaluate the influences of duration of epilepsy on the topological organization of brain network in focal epilepsy patients with normal MRI using the graph theoretical analysis based on diffusion tenor imaging. METHODS: We prospectively enrolled 66 patients with focal epilepsy (18/66 patients were newly diagnosed) and 84 healthy subjects...
January 17, 2018: Acta Neurologica Scandinavica
https://www.readbyqxmd.com/read/29344465/grey-and-white-matter-alterations-in-juvenile-myoclonic-epilepsy-a-comprehensive-review
#17
REVIEW
Ji Hyun Kim
Juvenile myoclonic epilepsy (JME) has been classified as a syndrome of idiopathic generalized epilepsy and is characterized by a strong genetic basis, age-specific onset of seizures, specific types of seizures, generalized spike-wave discharges on electroencephalography, and a lack of focal abnormality on magnetic resonance imaging (MRI). Recently, a wide range of advanced neuroimaging techniques have been utilized to elucidate the neuroanatomical substrates and pathophysiological mechanisms underlying JME...
December 2017: Journal of Epilepsy Research
https://www.readbyqxmd.com/read/29341752/tensor-network-simulations-of-the-surface-code-under-realistic-noise
#18
Andrew S Darmawan, David Poulin
The surface code is a many-body quantum system, and simulating it in generic conditions is computationally hard. While the surface code is believed to have a high threshold, the numerical simulations used to establish this threshold are based on simplified noise models. We present a tensor-network algorithm for simulating error correction with the surface code under arbitrary local noise. We use this algorithm to study the threshold and the subthreshold behavior of the amplitude damping and systematic rotation channels...
July 28, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29323797/relations-between-cortical-thickness-serotonin-1a-receptor-binding-and-structural-connectivity-a-multimodal-imaging-study
#19
Rajapillai L I Pillai, Ashwin Malhotra, Deborah D Rupert, Bennett Weschler, John C Williams, Mengru Zhang, Jie Yang, J John Mann, Maria A Oquendo, Ramin V Parsey, Christine DeLorenzo
Serotonin 1A (5-HT1A ) receptors play a direct role in neuronal development, cell proliferation, and dendritic branching. We hypothesized that variability in 5-HT1A binding can affect cortical thickness, and may account for a subtype of major depressive disorder (MDD) in which both are altered. To evaluate this, we measured cortical thickness from structural magnetic resonance imaging (MRI) and 5-HT1A binding by positron emission tomography (PET) in an exploratory study. To examine a range of 5-HT1A binding and cortical thickness values, we recruited 25 healthy controls and 19 patients with MDD...
February 2018: Human Brain Mapping
https://www.readbyqxmd.com/read/29321969/the-two-year-progression-of-structural-and-functional-cerebral-mri-in-amyotrophic-lateral-sclerosis
#20
R A L Menke, M Proudfoot, K Talbot, M R Turner
MRI has emerged as one of several urgently needed candidate disease progression biomarkers for the neurodegenerative disorder amyotrophic lateral sclerosis (ALS), not least due to its unique ability to non-invasively assess structural and functional cerebral pathology. We sought to identify the extent of detectable change in cerebral MRI metrics over a more prolonged period. Analysis of multi-modal MRI data was performed in a cohort of sixteen patients (13 ALS and 3 with primary lateral sclerosis) in whom it was possible to acquire six-monthly images over two years...
2018: NeuroImage: Clinical
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