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Cortical connectome

Giuseppina Caiazzo, Michele Fratello, Federica Di Nardo, Francesca Trojsi, Gioacchino Tedeschi, Fabrizio Esposito
PURPOSE: Advances in computational network analysis have enabled the characterization of topological properties of human brain networks (connectomics) from high angular resolution diffusion imaging (HARDI) MRI structural measurements. In this study, the effect of changing the diffusion weighting (b value) and sampling (number of gradient directions) was investigated in ten healthy volunteers, with specific focus on graph theoretical network metrics used to characterize the human connectome...
March 8, 2018: Neuroradiology
Nicolas Honnorat, Christos Davatzikos
The introduction of graph theory in neuroimaging has provided invaluable tools for the study of brain connectivity. These methods require the definition of a graph, which is typically derived by estimating the effective connectivity between brain regions through the optimization of an ill-posed inverse problem. Considerable efforts have been devoted to the development of methods extracting sparse connectivity graphs. The present paper aims at highlighting the benefits of an alternative approach. We investigate low-rank L2 regularized matrices recently introduced under the denomination of Riccati regularized precision matrices...
June 2017: Information Processing in Medical Imaging: Proceedings of the ... Conference
You Zhai, Jian Zhai
This paper uses a newly defined functional connectome and connectome values calculated in time domain of simulated neurotransmitter release (NTR) from an electrocorticogram (ECoG) to distinguish between conditioned and unconditioned stimuli. The NTR derived from multiple channels releasing one quantum at the same time suggests that one functional connectome occurs across those channels at that time. During the first 600 ms after conditional stimulation, the connectome indexes of the 64-channel NTR trains were sorted from the 8 to 20 Hz band obtained from filtered rabbit ECoGs recorded from the visual cortices...
2018: Frontiers in Behavioral Neuroscience
Csaba Kerepesi, Bálint Varga, Balázs Szalkai, Vince Grolmusz
In the applications of the graph theory, it is unusual that one considers numerous, pairwise different graphs on the very same set of vertices. In the case of human braingraphs or connectomes, however, this is the standard situation: the nodes correspond to anatomically identified cerebral regions, and two vertices are connected by an edge if a diffusion MRI-based workflow identifies a fiber of axons, running between the two regions, corresponding to the two vertices. Therefore, if we examine the braingraphs of n subjects, then we have n graphs on the very same, anatomically identified vertex set...
February 26, 2018: Neuroscience Letters
J Matias Palva, Sheng H Wang, Satu Palva, Alexander Zhigalov, Simo Monto, Matthew J Brookes, Jan-Mathijs Schoffelen, Karim Jerbi
When combined with source modeling, magneto- (MEG) and electroencephalography (EEG) can be used to study long-range interactions among cortical processes non-invasively. Estimation of such inter-areal connectivity is nevertheless hindered by instantaneous field spread and volume conduction, which artificially introduce linear correlations and impair source separability in cortical current estimates. To overcome the inflating effects of linear source mixing inherent to standard interaction measures, alternative phase- and amplitude-correlation based connectivity measures, such as imaginary coherence and orthogonalized amplitude correlation have been proposed...
February 22, 2018: NeuroImage
Edwin van Dellen, Iris E Sommer, Marc M Bohlken, Prejaas Tewarie, Laurijn Draaisma, Andrew Zalesky, Maria Di Biase, Jesse A Brown, Linda Douw, Willem M Otte, René C W Mandl, Cornelis J Stam
One of the challenges of brain network analysis is to directly compare network organization between subjects, irrespective of the number or strength of connections. In this study, we used minimum spanning tree (MST; a unique, acyclic subnetwork with a fixed number of connections) analysis to characterize the human brain network to create an empirical reference network. Such a reference network could be used as a null model of connections that form the backbone structure of the human brain. We analyzed the MST in three diffusion-weighted imaging datasets of healthy adults...
February 21, 2018: Human Brain Mapping
Michel R T Sinke, Willem M Otte, Daan Christiaens, Oliver Schmitt, Alexander Leemans, Annette van der Toorn, R Angela Sarabdjitsingh, Marian Joëls, Rick M Dijkhuizen
Diffusion MRI (dMRI)-based tractography offers unique abilities to map whole-brain structural connections in human and animal brains. However, dMRI-based tractography indirectly measures white matter tracts, with suboptimal accuracy and reliability. Recently, sophisticated methods including constrained spherical deconvolution (CSD) and global tractography have been developed to improve tract reconstructions through modeling of more complex fiber orientations. Our study aimed to determine the accuracy of connectome reconstruction for three dMRI-based tractography approaches: diffusion tensor (DT)-based, CSD-based and global tractography...
February 20, 2018: Brain Structure & Function
Carme Uribe, Barbara Segura, Hugo Cesar Baggio, Alexandra Abos, Anna Isabel Garcia-Diaz, Anna Campabadal, Maria Jose Marti, Francesc Valldeoriola, Yaroslau Compta, Eduard Tolosa, Carme Junque
INTRODUCTION: Cortical brain atrophy detectable with MRI in non-demented advanced Parkinson's disease (PD) is well characterized, but its presence in early disease stages is still under debate. We aimed to investigate cortical atrophy patterns in a large sample of early untreated PD patients using a hypothesis-free data-driven approach. METHODS: Seventy-seven de novo PD patients and 50 controls from the Parkinson's Progression Marker Initiative database with T1-weighted images in a 3-tesla Siemens scanner were included in this study...
February 8, 2018: Parkinsonism & related Disorders
Hikaru Fukutomi, Matthew F Glasser, Hui Zhang, Joonas A Autio, Timothy S Coalson, Tomohisa Okada, Kaori Togashi, David C Van Essen, Takuya Hayashi
We present distinct patterns of neurite distribution in the human cerebral cortex using diffusion magnetic resonance imaging (MRI). We analyzed both high-resolution structural (T1w and T2w images) and diffusion MRI data in 505 subjects from the Human Connectome Project. Neurite distributions were evaluated using the neurite orientation dispersion and density imaging (NODDI) model, optimized for gray matter, and mapped onto the cortical surface using a method weighted towards the cortical mid-thickness to reduce partial volume effects...
February 12, 2018: NeuroImage
Alexander Woodward, Tsutomu Hashikawa, Masahide Maeda, Takaaki Kaneko, Keigo Hikishima, Atsushi Iriki, Hideyuki Okano, Yoko Yamaguchi
We present a new 3D digital brain atlas of the non-human primate, common marmoset monkey (Callithrix jacchus), with MRI and coregistered Nissl histology data. To the best of our knowledge this is the first comprehensive digital 3D brain atlas of the common marmoset having normalized multi-modal data, cortical and sub-cortical segmentation, and in a common file format (NIfTI). The atlas can be registered to new data, is useful for connectomics, functional studies, simulation and as a reference. The atlas was based on previously published work but we provide several critical improvements to make this release valuable for researchers...
February 13, 2018: Scientific Data
Răzvan Gămănuţ, Henry Kennedy, Zoltán Toroczkai, Mária Ercsey-Ravasz, David C Van Essen, Kenneth Knoblauch, Andreas Burkhalter
The inter-areal wiring pattern of the mouse cerebral cortex was analyzed in relation to a refined parcellation of cortical areas. Twenty-seven retrograde tracer injections were made in 19 areas of a 47-area parcellation of the mouse neocortex. Flat mounts of the cortex and multiple histological markers enabled detailed counts of labeled neurons in individual areas. The observed log-normal distribution of connection weights to each cortical area spans 5 orders of magnitude and reveals a distinct connectivity profile for each area, analogous to that observed in macaques...
February 7, 2018: Neuron
Haixiao Du, Mingrui Xia, Kang Zhao, Xuhong Liao, Huazhong Yang, Yu Wang, Yong He
The recent collection of unprecedented quantities of neuroimaging data with high spatial resolution has led to brain network big data. However, a toolkit for fast and scalable computational solutions is still lacking. Here, we developed the PArallel Graph-theoretical ANalysIs (PAGANI) Toolkit based on a hybrid central processing unit-graphics processing unit (CPU-GPU) framework with a graphical user interface to facilitate the mapping and characterization of high-resolution brain networks. Specifically, the toolkit provides flexible parameters for users to customize computations of graph metrics in brain network analyses...
February 7, 2018: Human Brain Mapping
Gabriel Mangeat, Atef Badji, Russell Ouellette, Constantina A Treaba, Elena Herranz, Tobias Granberg, Céline Louapre, Nikola Stikov, Jacob A Sloane, Pierre Bellec, Caterina Mainero, Julien Cohen-Adad
The aim of this study was to investigate the interplay between structural connectivity and cortical demyelination in early multiple sclerosis. About 27 multiple sclerosis patients and 18 age-matched controls underwent two MRI scanning sessions. The first was done at 7T and involved acquiring quantitative T1 and T2 * high-resolution maps to estimate cortical myelination. The second was done on a Connectom scanner and consisted of acquiring high angular resolution diffusion-weighted images to compute white matter structural connectivity metrics: strength, clustering and local efficiency...
February 6, 2018: Human Brain Mapping
Frithjof Kruggel
The human neocortex shows a considerable individual structural variability. While primary gyri and sulci are found in all normally developed brains and bear clear-cut gross structural descriptions, secondary structures are highly variable and not present in all brains. The blend of common and individual structures poses challenges when comparing structural and functional results from quantitative neuroimaging studies across individuals, and sets limits on the precision of location information much above the spatial resolution of current neuroimaging methods...
February 1, 2018: NeuroImage
Mohsen Alavash, Sung-Joo Lim, Christiane Thiel, Bernhard Sehm, Lorenz Deserno, Jonas Obleser
Dopamine underlies important aspects of cognition, and has been suggested to boost cognitive performance. However, how dopamine modulates the large-scale cortical dynamics during cognitive performance has remained elusive. Using functional MRI during a working memory task in healthy young human listeners, we investigated the effect of levodopa (l-dopa) on two aspects of cortical dynamics, blood oxygen-level-dependent (BOLD) signal variability and the functional connectome of large-scale cortical networks. We here show that enhanced dopaminergic signaling modulates the two potentially interrelated aspects of large-scale cortical dynamics during cognitive performance, and the degree of these modulations is able to explain inter-individual differences in l-dopa-induced behavioral benefits...
February 2, 2018: NeuroImage
Antonios Makropoulos, Emma C Robinson, Andreas Schuh, Robert Wright, Sean Fitzgibbon, Jelena Bozek, Serena J Counsell, Johannes Steinweg, Katy Vecchiato, Jonathan Passerat-Palmbach, Gregor Lenz, Filippo Mortari, Tencho Tenev, Eugene P Duff, Matteo Bastiani, Lucilio Cordero-Grande, Emer Hughes, Nora Tusor, Jacques-Donald Tournier, Jana Hutter, Anthony N Price, Rui Pedro A G Teixeira, Maria Murgasova, Suresh Victor, Christopher Kelly, Mary A Rutherford, Stephen M Smith, A David Edwards, Joseph V Hajnal, Mark Jenkinson, Daniel Rueckert
The Developing Human Connectome Project (dHCP) seeks to create the first 4-dimensional connectome of early life. Understanding this connectome in detail may provide insights into normal as well as abnormal patterns of brain development. Following established best practices adopted by the WU-MINN Human Connectome Project (HCP), and pioneered by FreeSurfer, the project utilises cortical surface-based processing pipelines. In this paper, we propose a fully automated processing pipeline for the structural Magnetic Resonance Imaging (MRI) of the developing neonatal brain...
January 30, 2018: NeuroImage
Xavier Guell, John D E Gabrieli, Jeremy D Schmahmann
Delineation of functional topography is critical to the evolving understanding of the cerebellum's role in a wide range of nervous system functions. We used data from the Human Connectome Project (n = 787) to analyze cerebellar fMRI task activation (motor, working memory, language, social and emotion processing) and resting-state functional connectivity calculated from cerebral cortical seeds corresponding to the peak Cohen's d of each task contrast. The combination of exceptional statistical power, activation from both motor and multiple non-motor tasks in the same participants, and convergent resting-state networks in the same participants revealed novel aspects of the functional topography of the human cerebellum...
February 1, 2018: NeuroImage
Marc Tittgemeyer, Lionel Rigoux, Thomas R Knösche
One of the major challenges in systems neuroscience is to identify brain networks and unravel their significance for brain function -this has led to the concept of the 'connectome'. Connectomes are currently extensively studied in large-scale international efforts at multiple scales, and follow different definitions with respect to their connections as well as their elements. Perhaps the most promising avenue for defining the elements of connectomes originates from the notion that individual brain areas maintain distinct (long-range) connection profiles...
January 30, 2018: NeuroImage
Lachlan T Strike, Narelle K Hansell, Baptiste Couvy-Duchesne, Paul M Thompson, Greig I de Zubicaray, Katie L McMahon, Margaret J Wright
Quantifying the genetic architecture of the cerebral cortex is necessary for understanding disease and changes to the brain across the lifespan. Prior work shows that both surface area (SA) and cortical thickness (CT) are heritable. However, we do not yet understand the extent to which region-specific genetic factors (i.e., independent of global effects) play a dominant role in the regional patterning or inter-regional associations across the cortex. Using a population sample of young adult twins (N = 923), we show that the heritability of SA and CT varies widely across regions, generally independent of measurement error...
January 25, 2018: Cerebral Cortex
Xiao Liu, Jacco A de Zwart, Marieke L Schölvinck, Catie Chang, Frank Q Ye, David A Leopold, Jeff H Duyn
Cortical activity during periods of rest is punctuated by widespread, synchronous events in both electrophysiological and hemodynamic signals, but their behavioral relevance remains unclear. Here we report that these events correspond to momentary drops in cortical arousal and are associated with activity changes in the basal forebrain and thalamus. Combining fMRI and electrophysiology in macaques, we first establish that fMRI transients co-occur with spectral shifts in local field potentials (LFPs) toward low frequencies...
January 26, 2018: Nature Communications
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