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Dynamic functional connectivity

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https://www.readbyqxmd.com/read/28428738/improved-localization-of-seizure-onset-zones-using-spatiotemporal-constraints-and-time-varying-source-connectivity
#1
Juan D Martinez-Vargas, Gregor Strobbe, Kristl Vonck, Pieter van Mierlo, German Castellanos-Dominguez
Presurgical evaluation of brain neural activity is commonly carried out in refractory epilepsy patients to delineate as accurately as possible the seizure onset zone (SOZ) before epilepsy surgery. In practice, any subjective interpretation of electroencephalographic (EEG) recordings is hindered mainly because of the highly stochastic behavior of the epileptic activity. We propose a new method for dynamic source connectivity analysis that aims to accurately localize the seizure onset zones by explicitly including temporal, spectral, and spatial information of the brain neural activity extracted from EEG recordings...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28425971/%C3%AF-%C3%A2-cells-feature-de-ubiquitination-of-slc-transporters-and-increased-levels-and-fluxes-of-amino-acids
#2
André Bordinassi Medina, Marcin Banaszczak, Yang Ni, Ina Aretz, David Meierhofer
Solute carrier (SLC) transporters are a diverse group of membrane transporter proteins that regulate the cellular flux and distribution of endogenous and xenobiotic compounds. Post-translational modifications (PTMs), such as ubiquitination, have recently emerged as one of the major regulatory mechanisms in protein function and localization. Previously, we showed that SLC amino acid transporters were on average 6-fold de-ubiquitinated and increased amino acid levels were detected in ρ⁰ cells (lacking mitochondrial DNA, mtDNA) compared to parental cells...
April 20, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28424599/electrophysiological-sequelae-of-hemispherotomy-in-ipsilateral-human-cortex
#3
Ammar H Hawasli, Ravi Chacko, Nicholas P Szrama, David T Bundy, Mrinal Pahwa, Chester K Yarbrough, Brian J Dlouhy, David D Limbrick, Dennis L Barbour, Matthew D Smyth, Eric C Leuthardt
Objectives: Hemispheric disconnection has been used as a treatment of medically refractory epilepsy and evolved from anatomic hemispherectomy to functional hemispherectomies to hemispherotomies. The hemispherotomy procedure involves disconnection of an entire hemisphere with limited tissue resection and is reserved for medically-refractory epilepsy due to diffuse hemispheric disease. Although it is thought to be effective by preventing seizures from spreading to the contralateral hemisphere, the electrophysiological effects of a hemispherotomy on the ipsilateral hemisphere remain poorly defined...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28423507/tgf-%C3%AE-independent-ctgf-induction-regulates-cell-adhesion-mediated-drug-resistance-by-increasing-collagen-i-in-hcc
#4
Yeonhwa Song, Jin-Sun Kim, Eun Kyung Choi, Joon Kim, Kang Mo Kim, Haeng Ran Seo
Hepatocellular carcinoma (HCC) is resistant to conventional chemotherapeutic agents and remains an unmet medical need. Here, we demonstrate a mechanism of cell adhesion-mediated drug resistance using a variety of HCC spheroid models to overcome environment-mediated drug resistance in HCC. We classified spheroids into two groups, tightly compacted and loosely compacted aggregates, based on investigation of dynamics of spheroid formation. Our results show that compactness of HCC spheroids correlated with fibroblast-like characteristics, collagen 1A1 (COL1A1) content, and capacity for chemoresistance...
March 28, 2017: Oncotarget
https://www.readbyqxmd.com/read/28423313/power-grid-protection-of-the-muscle-mitochondrial-reticulum
#5
Brian Glancy, Lisa M Hartnell, Christian A Combs, Armel Fenmou, Junhui Sun, Elizabeth Murphy, Sriram Subramaniam, Robert S Balaban
Mitochondrial network connectivity enables rapid communication and distribution of potential energy throughout the cell. However, this connectivity puts the energy conversion system at risk, because damaged elements could jeopardize the entire network. Here, we demonstrate the mechanisms for mitochondrial network protection in heart and skeletal muscle (SKM). We find that the cardiac mitochondrial reticulum is segmented into subnetworks comprising many mitochondria linked through abundant contact sites at highly specific intermitochondrial junctions (IMJs)...
April 18, 2017: Cell Reports
https://www.readbyqxmd.com/read/28421767/base-layer-influence-on-protonated-aminosilane-gradient-wettability
#6
Kayesh M Ashraf, Chenyu Wang, Sithara S Nair, Kenneth J Wynne, Daniel A Higgins, Maryanne M Collinson
Protonated amine gradients have been prepared on silicon wafers via programmed controlled rate infusion (CRI) with varying degrees of hydrophobicity and characterized by X-ray photoelectron spectroscopy (XPS) and static and Wilhelmy plate dynamic contact angle measurements. Initially, base layers were spin coated from sols containing tetramethoxysilane (TMOS) and either phenyltrimethoxysilane (PTMOS), dimethyldimethoxysilane (DMDMOS), or octyltrimethoxysilane (OTMOS, C8). Amine gradients were then prepared from 3-aminopropyltriethoxysilane (APTEOS) via CRI...
April 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28419208/interhemispheric-synchrony-of-spontaneous-cortical-states-at-the-cortical-column-level
#7
Kazunori O'Hashi, Tomer Fekete, Thomas Deneux, Rina Hildesheim, Cees van Leeuwen, Amiram Grinvald
In cat early visual cortex, neural activity patterns resembling evoked orientation maps emerge spontaneously under anesthesia. To test if such patterns are synchronized between hemispheres, we performed bilateral imaging in anesthetized cats using a new improved voltage-sensitive dye. We observed map-like activity patterns spanning early visual cortex in both hemispheres simultaneously. Patterns virtually identical to maps associated with the cardinal and oblique orientations emerged as leading principal components of the spontaneous fluctuations, and the strength of transient orientation states was correlated with their duration, providing evidence that these maps are transiently attracting states...
April 13, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28417233/a-posterior-to-anterior-shift-of-brain-functional-dynamics-in-aging
#8
Han Zhang, Annie Lee, Anqi Qiu
Convergent evidence from task-based functional magnetic resonance imaging (fMRI) studies suggests a posterior-to-anterior shift as an adaptive compensatory scaffolding mechanism for aging. This study aimed to investigate whether brain functional dynamics at rest follow the same scaffolding mechanism for aging using a large Chinese sample aged from 22 to 79 years (n = 277). We defined a probability of brain regions being hubs over a period of time to characterize functional hub dynamic, and defined variability of the functional connectivity to characterize dynamic functional connectivity using resting-state fMRI...
April 17, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28416459/the-error-of-broca-from-the-traditional-localizationist-concept-to-a-connectomal-anatomy-of-human-brain
#9
REVIEW
Hugues Duffau
Neurology, especially aphasiology, was mainly built on behavioral-structural correlations ("lesion method"). In this setting, Broca's area has been considered as the "speech area"; moreover, this observation led to localizationism. However, advances in brain mapping techniques, as functional neuroimaging and direct electrical stimulation in patients undergoing awake surgery for gliomas, has resulted in a paradigmatic shift regarding models of neural architecture. In fact, the brain is organized in distributed complex networks underpinning sensorimotor, visuospatial, language, cognitive and emotional functions...
April 14, 2017: Journal of Chemical Neuroanatomy
https://www.readbyqxmd.com/read/28415249/traveling-waves-and-breathers-in-an-excitatory-inhibitory-neural-field
#10
Stefanos E Folias
We study existence and stability of traveling activity bump solutions in an excitatory-inhibitory (E-I) neural field with Heaviside firing rate functions by deriving existence conditions for traveling bumps and an Evans function to analyze their spectral stability. Subsequently, we show that these existence and stability results reduce, in the limit of wave speed c→0, to the equivalent conditions developed for the stationary bump case. Using the results for the stationary bump case, we show that drift bifurcations of stationary bumps serve as a mechanism for generating traveling bump solutions in the E-I neural field as parameters are varied...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415244/effect-of-the-salt-induced-micellar-microstructure-on-the-nonlinear-shear-flow-behavior-of-ionic-cetylpyridinium-chloride-surfactant-solutions
#11
D Gaudino, R Pasquino, H Kriegs, N Szekely, W Pyckhout-Hintzen, M P Lettinga, N Grizzuti
The shear flow dynamics of linear and branched wormlike micellar systems based on cetylpyridinium chloride and sodium salicylate in brine solution is investigated through rheometric and scattering techniques. In particular, the flow and the structural flow response are explored via velocimetry measurements and rheological and rheometric small-angle neutron scattering (SANS) experiments, respectively. Although all micellar solutions display a similar shear thinning behavior in the nonlinear regime, the experimental results show that shear banding sets in only when the micelle contour length L[over ¯] is sufficiently long, independent of the nature of the micellar connections (either linear or branched micelles)...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28412440/transient-networks-of-spatio-temporal-connectivity-map-communication-pathways-in-brain-functional-systems
#12
Alessandra Griffa, Benjamin Ricaud, Kirell Benzi, Xavier Bresson, Alessandro Daducci, Pierre Vandergheynst, Jean-Philippe Thiran, Patric Hagmann
The study of brain dynamics enables us to characterize the time-varying functional connectivity among distinct neural groups. However, current methods suffer from the absence of structural connectivity information. We propose to integrate infra-slow neural oscillations and anatomical-connectivity maps, as derived from functional and diffusion MRI, in a multilayer-graph framework that captures transient networks of spatio-temporal connectivity. These networks group anatomically wired and temporary synchronized brain regions and encode the propagation of functional activity on the structural connectome...
April 12, 2017: NeuroImage
https://www.readbyqxmd.com/read/28412156/tyrosine-oxidation-and-nitration-in-transmembrane-peptides-is-connected-to-lipid-peroxidation
#13
Silvina Bartesaghminni, Daniel Herrera, Débora M Martinez, Ariel Petruk, Verónica Demicheli, Madia Trujillo, Marcelo A Martí, Darío A Estrín, Rafael Radi
Tyrosine nitration is an oxidative post-translational modification that can occur in proteins associated to hydrophobic bio-structures such as membranes and lipoproteins. In this work, we have studied tyrosine nitration in membranes using a model system consisting of phosphatidylcholine liposomes with pre-incorporated tyrosine-containing 23 amino acid transmembrane peptides. Tyrosine residues were located at positions 4, 8 or 12 of the amino terminal, resulting in different depths in the bilayer. Tyrosine nitration was accomplished by exposure to peroxynitrite and a peroxyl radical donor or hemin in the presence of nitrite...
April 13, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28409572/-fret-based-biosensors-in-cell-migration-research
#14
Sławomir Lasota, Zbigniew Baster, Tomasz Witko, Eliza Zimoląg, Jolanta Sroka, Zenon Rajfur, Zbigniew Madeja
Cell migration is a complicated process, which is crucial for functioning of multicellular organisms. Multiple signalling pathways are deeply involved in the precise control of consecutive cell migration stages based on remodelling of the actin cytoskeleton. Small Rho GTPases (RhoA, Rac1 and Cdc42) as well as multiple protein and lipid kinases, calcium ions and mechanosensors are crucial components in this process. Exploration of those complicated correlations is possible with constant advancement of fluorescence microscopy...
2017: Postepy Biochemii
https://www.readbyqxmd.com/read/28405356/nonlinear-growth-an-origin-of-hub-organization-in-complex-networks
#15
Roman Bauer, Marcus Kaiser
Many real-world networks contain highly connected nodes called hubs. Hubs are often crucial for network function and spreading dynamics. However, classical models of how hubs originate during network development unrealistically assume that new nodes attain information about the connectivity (for example the degree) of existing nodes. Here, we introduce hub formation through nonlinear growth where the number of nodes generated at each stage increases over time and new nodes form connections independent of target node features...
March 2017: Royal Society Open Science
https://www.readbyqxmd.com/read/28400717/listening-to-rhythmic-music-reduces-connectivity-within-the-basal-ganglia-and-the-reward-system
#16
Hans P Brodal, Berge Osnes, Karsten Specht
Music can trigger emotional responses in a more direct way than any other stimulus. In particular, music-evoked pleasure involves brain networks that are part of the reward system. Furthermore, rhythmic music stimulates the basal ganglia and may trigger involuntary movements to the beat. In the present study, we created a continuously playing rhythmic, dance floor-like composition where the ambient noise from the MR scanner was incorporated as an additional instrument of rhythm. By treating this continuous stimulation paradigm as a variant of resting-state, the data was analyzed with stochastic dynamic causal modeling (sDCM), which was used for exploring functional dependencies and interactions between core areas of auditory perception, rhythm processing, and reward processing...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28390385/segment-scale-force-level-theory-of-mesoscopic-dynamic-localization-and-entropic-elasticity-in-entangled-chain-polymer-liquids
#17
Zachary E Dell, Kenneth S Schweizer
We develop a segment-scale, force-based theory for the breakdown of the unentangled Rouse model and subsequent emergence of isotropic mesoscopic localization and entropic elasticity in chain polymer liquids in the absence of ergodicity-restoring anisotropic reptation or activated hopping motion. The theory is formulated in terms of a conformational N-dynamic-order-parameter generalized Langevin equation approach. It is implemented using a universal field-theoretic Gaussian thread model of polymer structure and closed at the level of the chain dynamic second moment matrix...
April 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28390361/the-role-of-li-ions-in-the-gas-phase-dehydrohalogenation-and-dehydration-reactions-of-i-c3h7br-and-i-c3h7oh-molecules-studied-by-radiofrequency-guided-ion-beam-techniques-and-ab-initio-methods
#18
E López, J M Lucas, J de Andrés, M Albertí, J M Bofill, A Aguilar
Gas phase reactive collisions between lithium ions and i-C3H7X (X = Br, OH) molecules have been studied under single collision conditions in the center of mass (CM) 0.01-10.00 eV energy range using a radiofrequency-guided ion beam apparatus. Mass spectrometry analysis of the products did show the presence of [C3H6-Li](+), [HX-Li](+), C3H7(+), and C2H3(+) as well as of the [Li-i-C3H7Br](+) adduct while [Li-i-C3H7OH](+) was hardly detected. For all these reactive processes, the corresponding cross sections have been measured in absolute units as a function of the CM collision energy...
April 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28390165/default-mode-and-task-positive-networks-connectivity-during-the-n-back-task-in-remitted-depressed-patients-with-or-without-emotional-residual-symptoms
#19
Pauline Delaveau, Tiago Arruda Sanchez, Ricardo Steffen, Karine Deschet, Maritza Jabourian, Vincent Perlbarg, Emerson Leandro Gasparetto, Stéphanie Dubal, Jorge Costa E Silva, Philippe Fossati
Clinical remission of depression may be associated with emotional residual symptoms. We studied the association of emotional blunting, rumination with neural networks dynamics in remitted depressed patients and cognitive performance during an N-Back task. Twenty-six outpatients in remission of depression (Hamilton Depressive rating scale score <7) performed an N-Back task during fMRI assessment. All patients had been treated by paroxetine for a minimum of 4 months. Two subgroups of patients [Nonemotionally blunted (NEB) = 14 and emotionally blunted (EB) = 12] were determined...
April 8, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28386778/gaba-content-within-medial-prefrontal-cortex-predicts-the-variability-of-fronto-limbic-effective-connectivity
#20
Stefano Delli Pizzi, Piero Chiacchieretta, Dante Mantini, Giovanna Bubbico, Richard A Edden, Marco Onofrj, Antonio Ferretti, Laura Bonanni
The amygdala-medial prefrontal cortex (mPFC) circuit plays a key role in social behavior. The amygdala and mPFC are bidirectionally connected, functionally and anatomically, via the uncinate fasciculus. Recent evidence suggests that GABA-ergic neurotransmission within the mPFC could be central to the regulation of amygdala activity related to emotions and anxiety processing. However, the functional and neurochemical interactions within amygdala-mPFC circuits are unclear. In the current study, multimodal magnetic resonance imaging techniques were combined to investigate effective connectivity within the amygdala-mPFC network and its relationship with mPFC neurotransmission in 22 healthy subjects aged between 41 and 88 years...
April 6, 2017: Brain Structure & Function
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