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Granger causality

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https://www.readbyqxmd.com/read/27915993/directed-functional-connectivity-of-posterior-cingulate-cortex-and-whole-brain-in-alzheimer-s-disease-and-mild-cognitive-impairment
#1
Enyan Yu, Zhengluan Liao, Dewang Mao, Qi Zhang, Gongjun Ji, Yumei Li, Zhongxiang Ding
BACKGROUND: Impaired functional connectivity in the default mode network (DMN) is supposedly involved in Alzheimer's disease (AD) progression. The posterior cingulate cortex (PCC) might be an imaging marker for monitoring AD progression. OBJECTIVE: To investigate the alterations in the directed functional connectivity between the PCC and whole brain in patients with AD, patients with mild cognitive impairment (MCI), and healthy controls. METHODS: A total of 116 enrolled participants were divided into three groups: AD (n=32), MCI (n=26), and controls (n=58)...
December 1, 2016: Current Alzheimer Research
https://www.readbyqxmd.com/read/27913167/gamma-band-directional-interactions-between-basal-forebrain-and-visual-cortex-during-wake-and-sleep-states
#2
Jayakrishnan Nair, Arndt-Lukas Klaassen, Jordan Poirot, Alexei Vyssotski, Björn Rasch, Gregor Rainer
The basal forebrain (BF) is an important regulator of cortical excitability and responsivity to sensory stimuli, and plays a major role in wake-sleep regulation. While the impact of BF on cortical EEG or LFP signals has been extensively documented, surprisingly little is known about LFP activity within BF. Based on bilateral recordings from rats in their home cage, we describe endogenous LFP oscillations in the BF during quiet wakefulness, rapid eye movement (REM) and slow wave sleep (SWS) states. Using coherence and Granger causality methods, we characterize directional influences between BF and visual cortex (VC) during each of these states...
November 29, 2016: Journal of Physiology, Paris
https://www.readbyqxmd.com/read/27905073/critical-comments-on-eeg-sensor-space-dynamical-connectivity-analysis
#3
Frederik Van de Steen, Luca Faes, Esin Karahan, Jitkomut Songsiri, Pedro A Valdes-Sosa, Daniele Marinazzo
Many different analysis techniques have been developed and applied to EEG recordings that allow one to investigate how different brain areas interact. One particular class of methods, based on the linear parametric representation of multiple interacting time series, is widely used to study causal connectivity in the brain. However, the results obtained by these methods should be interpreted with great care. The goal of this paper is to show, both theoretically and using simulations, that results obtained by applying causal connectivity measures on the sensor (scalp) time series do not allow interpretation in terms of interacting brain sources...
November 30, 2016: Brain Topography
https://www.readbyqxmd.com/read/27880004/causal-relationships-among-neurons-of-the-nucleus-incertus-and-the-hippocampal-theta-activity-in-the-rat
#4
Sergio Martínez-Bellver, Ana Cervera-Ferri, Aina Luque-García, Joana Martínez-Ricós, Alfonso Valverde-Navarro, Manuel Bataller, Juan Guerrero, Vicent Teruel-Marti
In recent years, a body of evidence has shown that the nucleus incertus (NI), in the dorsal tegmental pons, is a key node of the brainstem circuitry involved in hippocampal theta rhythmicity. Ascending reticular brainstem system activation evokes hippocampal theta rhythm with coupled neuronal activity in the NI. In a recent paper, we showed three populations of neurons in the NI with differential firings during hippocampal theta activation. The objective of this work is to better evaluate the causal relationship between the activity of NI neurons and the hippocampus during theta activation in order to further understand the role of the NI in the theta network...
November 23, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27875123/synergetic-and-redundant-information-flow-detected-by-unnormalized-granger-causality-application-to-resting-state-fmri
#5
Sebastiano Stramaglia, Leonardo Angelini, Guorong Wu, Jesus M Cortes, Luca Faes, Daniele Marinazzo
OBJECTIVES: We develop a framework for the analysis of synergy and redundancy in the pattern of information flow between subsystems of a complex network. METHODS: The presence of redundancy and/or synergy in multivariate time series data renders difficulty to estimate the neat flow of information from each driver variable to a given target. We show that adopting an unnormalized definition of Granger causality, one may put in evidence redundant multiplets of variables influencing the target by maximizing the total Granger causality to a given target, over all the possible partitions of the set of driving variables...
December 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/27868393/atypical-effective-connectivity-of-thalamo-cortical-circuits-in-autism-spectrum-disorder
#6
Heng Chen, Lucina Q Uddin, Youxue Zhang, Xujun Duan, Huafu Chen
Autism spectrum disorder (ASD) is a neurodevelopment disorder characterized by atypical connectivity within and across multiple brain systems. We aimed to explore information transmission from the sensory periphery to information processing centers of the brain across thalamo-cortical circuits in ASD. A large multicenter dataset from the autism brain imaging data exchange was utilized. A thalamus template derived from the Automatic Anatomic Labeling atlas was subdivided into six subregions corresponding to six cortical regions using a "winner-takes-all" strategy...
November 2016: Autism Research: Official Journal of the International Society for Autism Research
https://www.readbyqxmd.com/read/27867351/advice-taking-from-humans-and-machines-an-fmri-and-effective-connectivity-study
#7
Kimberly Goodyear, Raja Parasuraman, Sergey Chernyak, Poornima Madhavan, Gopikrishna Deshpande, Frank Krueger
With new technological advances, advice can come from different sources such as machines or humans, but how individuals respond to such advice and the neural correlates involved need to be better understood. We combined functional MRI and multivariate Granger causality analysis with an X-ray luggage-screening task to investigate the neural basis and corresponding effective connectivity involved with advice utilization from agents framed as experts. Participants were asked to accept or reject good or bad advice from a human or machine agent with low reliability (high false alarm rate)...
2016: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/27856312/empirical-validation-of-directed-functional-connectivity
#8
Ravi D Mill, Anto Bagic, Andreea Bostan, Walter Schneider, Michael W Cole
Mapping directions of influence in the human brain connectome represents the next phase in understanding its functional architecture. However, a host of methodological uncertainties have impeded the application of directed connectivity methods, which have primarily been validated via "ground truth" connectivity patterns embedded in simulated functional MRI (fMRI) and magneto-/electro-encephalography (MEG/EEG) datasets. Such simulations rely on many generative assumptions, and we hence utilized a different strategy involving empirical data in which a ground truth directed connectivity pattern could be anticipated with confidence...
November 14, 2016: NeuroImage
https://www.readbyqxmd.com/read/27846290/altered-effective-connectivity-of-the-primary-motor-cortex-in-stroke-a-resting-state-fmri-study-with-granger-causality-analysis
#9
Zhiyong Zhao, Xiangmin Wang, Mingxia Fan, Dazhi Yin, Limin Sun, Jie Jia, Chaozheng Tang, Xiaohui Zheng, Yuwei Jiang, Jie Wu, Jiayu Gong
The primary motor cortex (M1) is often abnormally recruited in stroke patients with motor disabilities. However, little is known about the alterations in the causal connectivity of M1 following stroke. The purpose of the present study was to investigate whether the effective connectivity of the ipsilesional M1 is disturbed in stroke patients who show different outcomes in hand motor function. 23 patients with left-hemisphere subcortical stroke were selected and divided into two subgroups: partially paralyzed hands (PPH) and completely paralyzed hands (CPH)...
2016: PloS One
https://www.readbyqxmd.com/read/27833547/new-insights-into-signed-path-coefficient-granger-causality-analysis
#10
Jian Zhang, Chong Li, Tianzi Jiang
Granger causality analysis, as a time series analysis technique derived from econometrics, has been applied in an ever-increasing number of publications in the field of neuroscience, including fMRI, EEG/MEG, and fNIRS. The present study mainly focuses on the validity of "signed path coefficient Granger causality," a Granger-causality-derived analysis method that has been adopted by many fMRI researches in the last few years. This method generally estimates the causality effect among the time series by an order-1 autoregression, and defines a positive or negative coefficient as an "excitatory" or "inhibitory" influence...
2016: Frontiers in Neuroinformatics
https://www.readbyqxmd.com/read/27833546/measures-of-coupling-between-neural-populations-based-on-granger-causality-principle
#11
REVIEW
Maciej Kaminski, Aneta Brzezicka, Jan Kaminski, Katarzyna J Blinowska
This paper shortly reviews the measures used to estimate neural synchronization in experimental settings. Our focus is on multivariate measures of dependence based on the Granger causality (G-causality) principle, their applications and performance in respect of robustness to noise, volume conduction, common driving, and presence of a "weak node." Application of G-causality measures to EEG, intracranial signals and fMRI time series is addressed. G-causality based measures defined in the frequency domain allow the synchronization between neural populations and the directed propagation of their electrical activity to be determined...
2016: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/27832153/inferring-weighted-directed-association-network-from-multivariate-time-series-with-a-synthetic-method-of-partial-symbolic-transfer-entropy-spectrum-and-granger-causality
#12
Yanzhu Hu, Huiyang Zhao, Xinbo Ai
Complex network methodology is very useful for complex system explorer. However, the relationships among variables in complex system are usually not clear. Therefore, inferring association networks among variables from their observed data has been a popular research topic. We propose a synthetic method, named small-shuffle partial symbolic transfer entropy spectrum (SSPSTES), for inferring association network from multivariate time series. The method synthesizes surrogate data, partial symbolic transfer entropy (PSTE) and Granger causality...
2016: PloS One
https://www.readbyqxmd.com/read/27830769/graphlet-characteristics-in-directed-networks
#13
Igor Trpevski, Tamara Dimitrova, Tommy Boshkovski, Nikola Stikov, Ljupcho Kocarev
Graphlet analysis is part of network theory that does not depend on the choice of the network null model and can provide comprehensive description of the local network structure. Here, we propose a novel method for graphlet-based analysis of directed networks by computing first the signature vector for every vertex in the network and then the graphlet correlation matrix of the network. This analysis has been applied to brain effective connectivity networks by considering both direction and sign (inhibitory or excitatory) of the underlying directed (effective) connectivity...
November 10, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27828859/aberrant-pulvinar-effective-connectivity-in-generalized-social-anxiety-disorder
#14
Reza Tadayonnejad, Heide Klumpp, Olusola Ajilore, Alex Leow, Kinh Luan Phan
Recent neuroimaging findings in general social anxiety disorder (gSAD) have extended our understanding of the neural mechanisms of gSAD beyond an amygdala-centric fear-based hyperactivity model to include other brain regions and networks relevant to salient cues. In particular, higher order areas compromising visual networks that process emotional and social information have been implicated. The pulvinar anchors this network and is a key regulatory node that mediates complex sensory inputs and the integration between limbic and frontal brain systems...
November 2016: Medicine (Baltimore)
https://www.readbyqxmd.com/read/27826091/detectability-of-granger-causality-for-subsampled-continuous-time-neurophysiological-processes
#15
Lionel Barnett, Anil K Seth
BACKGROUND: Granger causality is well established within the neurosciences for inference of directed functional connectivity from neurophysiological data. These data usually consist of time series which subsample a continuous-time biophysiological process. While it is well known that subsampling can lead to imputation of spurious causal connections where none exist, less is known about the effects of subsampling on the ability to reliably detect causal connections which do exist. NEW METHOD: We present a theoretical analysis of the effects of subsampling on Granger-causal inference...
November 5, 2016: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/27824611/uncoupling-of-cardiac-and-respiratory-rhythm-in-atrial-fibrillation
#16
Mirjana M Platiša, Tijana Bojić, Siniša U Pavlović, Nikola N Radovanović, Aleksandar Kalauzi
Rearranged origin of heart rhythm in patients with atrial fibrillation (AF) influences the regulation of the heart and consequently the respiratory rhythm, and the bidirectional interaction of these rhythms not documented. Hence, we examined coupling of the RR interval and the respiration (Resp) signal by coherence, Granger causality and the cross-sample entropy method of time series analysis in patients with AF and a healthy control group. In healthy subjects, the influence of respiration on cardiac rhythm was found as increased coherence at the breathing frequency (BF) range, significantly stronger interaction and synchrony from Resp to RR than from RR to Resp...
December 1, 2016: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/27810830/gait-influence-diagrams-in-parkinson-s-disease
#17
Peng Ren, Esin Karahan, Chao Chen, Ruixue Luo, Yayuan Geng, Jorge Francisco Bosch Bayard, Maria L Bringas, Dezhong Yao, Keith M Kendrick, Pedro A Valdes-Sosa
Previous studies have shown that gait patterns differ between Parkinson's disease (PD) patients and controls. However, almost all these studies focused only on univariate time series of a single variable. This approach cannot reveal detailed information of foot loading dynamics and the cooperative relationships of different anatomical plantar foot areas when the subjects walk. By contrast, we propose a novel multivariate method for analyzing gait patterns of the PD patients: Gait Influence Diagrams (GIDs). These are constructed by analyzing the Wiener-Akaike-Granger-Schweder influences between vertical ground reaction force signals at different plantar areas of both feet...
October 27, 2016: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/27810354/human-sensory-cortex-structure-and-top-down-controlling-brain-network-determine-individual-differences-in-perceptual-alternations
#18
Na Sang, Lijie Zhang, Lei Hao, Yongchao Wang, Xiaogang Wang, Fan Zhang, Hui Huang, Xin Hou, Yu Mao, Taiyong Bi, Jiang Qiu
Bistable perception is a type of subjective perception that spontaneously alternates between two perceptual interpretations of an ambiguous sensory input. Past functional magnetic resonance imaging (fMRI) studies have examined the activation patterns underlying bistable perception, yet the variability between individuals in the alternations is not well understood. Therefore, voxel-based morphometry (VBM) was introduced in this study to correlate the GM of the sensory cortex with the alternations of Rubin face-vase illusion in a large group of young adults...
October 31, 2016: Neuroscience Letters
https://www.readbyqxmd.com/read/27808125/decoding-of-top-down-cognitive-processing-for-ssvep-controlled-bmi
#19
Byoung-Kyong Min, Sven Dähne, Min-Hee Ahn, Yung-Kyun Noh, Klaus-Robert Müller
We present a fast and accurate non-invasive brain-machine interface (BMI) based on demodulating steady-state visual evoked potentials (SSVEPs) in electroencephalography (EEG). Our study reports an SSVEP-BMI that, for the first time, decodes primarily based on top-down and not bottom-up visual information processing. The experimental setup presents a grid-shaped flickering line array that the participants observe while intentionally attending to a subset of flickering lines representing the shape of a letter...
November 3, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27796968/the-causal-nexus-between-carbon-dioxide-emissions-and-agricultural-ecosystem-an-econometric-approach
#20
Samuel Asumadu-Sarkodie, Phebe Asantewaa Owusu
Achieving a long-term food security and preventing hunger include a better nutrition through sustainable systems of production, distribution, and consumption. Nonetheless, the quest for an alternative to increasing global food supply to meet the growing demand has led to the use of poor agricultural practices that promote climate change. Given the contribution of the agricultural ecosystem towards greenhouse gas (GHG) emissions, this study investigated the causal nexus between carbon dioxide emissions and agricultural ecosystem by employing a data spanning from 1961 to 2012...
October 27, 2016: Environmental Science and Pollution Research International
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