Determination of information flow direction among brain structures by a modified directed transfer function (dDTF) method

Transmission of EEG activity during a visual and auditory version of the working memory task based on the paradigm of linear syllogism was investigated. Our aim was to find possible similarities and differences in the synchronization patterns between brain structures during the same mental activity performed on different modality stimuli. The EEG activity transmission was evaluated by means of full frequency Directed Transfer Function (ffDTF) and short-time Directed Transfer Function (SDTF). SDTF provided information on dynamical propagation of EEG activity. The assortative mixing approach was applied to quantify coupling between regions of interest encompassing frontal, central and two posterior modules. The results showed similar schemes of coupling for both modalities with stronger coupling within the regions of interests than between them, which is concordant with the theories concerning efficient wiring and metabolic energy saving. The patterns of transmission showed main sources of activity in the anterior and posterior regions communicating intermittently in a broad frequency range. The differences between the patterns of transmission between the visual and auditory versions of working memory tasks were subtle and involved bigger propagation from the posterior electrodes towards the frontal ones during the visual task as well as from the temporal sites to the frontal ones during the auditory task.

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Studies on the Bottom-Up and Top-Down Neural Information Flow Alterations in Neurodegeneration

Journal of Alzheimer s Disease ◽

10.3233/jad-200590 ◽

2020 ◽

Vol 78 (1) ◽

pp. 169-183

Author(s):

Abolfazl Alipour ◽

Azadeh Mozhdehfarahbakhsh ◽

Saba Nouri ◽

Peyman Petramfar ◽

Mahshid Tahamtan ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Transfer Function ◽

Information Flow ◽

Healthy Controls ◽

Beta Band ◽

Top Down ◽

Directed Transfer Function ◽

Bottom Up ◽

Neural Information

Background: A proper explanation for perceptual symptoms in neurodegenerative disorders including Alzheimer’s disease and Parkinson’s disease (PD) is still lacking. Objective: This study aimed at investigating the imbalance between ‘bottom-up’ and ‘top-down’ information flow (IF) and processing in PD in relation with visual hallucination symptoms. Methods: Here, we looked at bottom-up and top-down IF markers using resting state electroencephalographic (EEG) data from PD patients analyzed through three different IF measures (direct Directed Transfer Function (dDTF), full frequency Directed Transfer Function (ff-DTF), and renormalized Partial Directed Coherence (rPDC). Results: We observed an increased gamma band IF and a reduced beta band IF in PD patients compared to healthy controls. Additionally, we noticed a reduced theta band IF in PD patients using dDTF as a measure of IF. By source localizing the EEG activity of the PD patients and healthy controls, we looked at the alterations of IF in the prefrontal cortex of PD patients as well. Conclusion: In line with previous studies, our results suggest that the delicate balance between bottom-up and top-down IF is disrupted in Parkinson’s disease potentially contributing to the cognitive symptoms of PD patients.

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Determination of positive realizations with reduced numbers of delays or without delays for discrete-time linear systems

Archives of Control Sciences ◽

10.2478/v10170-011-0035-x ◽

2012 ◽

Vol 22 (4) ◽

pp. 451-465 ◽

Cited By ~ 2

Author(s):

Tadeusz Kaczorek

Keyword(s):

Transfer Function ◽

Linear Systems ◽

Discrete Time ◽

Sufficient Conditions ◽

Diagram Method ◽

State Variable ◽

Discrete Time Systems ◽

Time Systems ◽

Time Linear

A new modified state variable diagram method is proposed for determination of positive realizations with reduced numbers of delays and without delays of linear discrete-time systems for a given transfer function. Sufficient conditions for the existence of the positive realizations of given proper transfer function are established. It is shown that there exists a positive realization with reduced numbers of delays if there exists a positive realization without delays but with greater dimension. The proposed methods are demonstrated on a numerical example.

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Error analyses of a Multi-Input-Multi-Output cantilever beam test

Journal of Vibration and Control ◽

10.1177/10775463211033733 ◽

2021 ◽

pp. 107754632110337

Author(s):

Arup Maji ◽

Fernando Moreu ◽

James Woodall ◽

Maimuna Hossain

Keyword(s):

Transfer Function ◽

Frequency Domain ◽

Cantilever Beam ◽

Transfer Functions ◽

Linear Superposition ◽

Transfer Function Matrix ◽

Error Analyses ◽

Pseudo Inverse ◽

Function Matrix

Multi-Input-Multi-Output vibration testing typically requires the determination of inputs to achieve desired response at multiple locations. First, the responses due to each input are quantified in terms of complex transfer functions in the frequency domain. In this study, two Inputs and five Responses were used leading to a 5 × 2 transfer function matrix. Inputs corresponding to the desired Responses are then computed by inversion of the rectangular matrix using Pseudo-Inverse techniques that involve least-squared solutions. It is important to understand and quantify the various sources of errors in this process toward improved implementation of Multi-Input-Multi-Output testing. In this article, tests on a cantilever beam with two actuators (input controlled smart shakers) were used as Inputs while acceleration Responses were measured at five locations including the two input locations. Variation among tests was quantified including its impact on transfer functions across the relevant frequency domain. Accuracy of linear superposition of the influence of two actuators was quantified to investigate the influence of relative phase information. Finally, the accuracy of the Multi-Input-Multi-Output inversion process was investigated while varying the number of Responses from 2 (square transfer function matrix) to 5 (full-rectangular transfer function matrix). Results were examined in the context of the resonances and anti-resonances of the system as well as the ability of the actuators to provide actuation energy across the domain. Improved understanding of the sources of uncertainty from this study can be used for more complex Multi-Input-Multi-Output experiments.

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Betweenness centrality for temporal multiplexes

Scientific Reports ◽

10.1038/s41598-021-84418-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Silvia Zaoli ◽

Piero Mazzarisi ◽

Fabrizio Lillo

Keyword(s):

Information Flow ◽

Real World ◽

Betweenness Centrality ◽

Temporal Structure ◽

Shortest Paths ◽

Single Layer ◽

Distance Metric ◽

Definition Of

AbstractBetweenness centrality quantifies the importance of a vertex for the information flow in a network. The standard betweenness centrality applies to static single-layer networks, but many real world networks are both dynamic and made of several layers. We propose a definition of betweenness centrality for temporal multiplexes. This definition accounts for the topological and temporal structure and for the duration of paths in the determination of the shortest paths. We propose an algorithm to compute the new metric using a mapping to a static graph. We apply the metric to a dataset of $$\sim 20$$ ∼ 20 k European flights and compare the results with those obtained with static or single-layer metrics. The differences in the airports rankings highlight the importance of considering the temporal multiplex structure and an appropriate distance metric.

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Ein neues Verfahren zur Bestimmung der Übertragungsfunktion G (s) aus den Zustandsraum-Parametern/A new method for the determination of the transfer function G (s) from the parameters of the space-state-representation

at - Automatisierungstechnik ◽

10.1524/auto.1979.27.112.52 ◽

1979 ◽

Vol 27 (1-12) ◽

Author(s):

K. ZEISKE

Keyword(s):

Transfer Function ◽

New Method ◽

State Representation ◽

Space State

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Multiresolution directed transfer function approach for segment-wise seizure classification of epileptic EEG signal

Cognitive Neurodynamics ◽

10.1007/s11571-021-09773-z ◽

2022 ◽

Author(s):

Dhanalekshmi P. Yedurkar ◽

Shilpa P. Metkar ◽

Thompson Stephan

Keyword(s):

Transfer Function ◽

Function Approach ◽

Eeg Signal ◽

Directed Transfer Function ◽

Seizure Classification

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METHOD OF INCREASING THE STABILITY OF THE INFORMATION AND COMMUNICATION NETWORK UNDER THE INFLUENCE OF THE ENEMY BASED ON THE DETERMINATION OF THE REFERENCE NETWORK VERSION

Электросвязь ◽

10.34832/elsv.2020.10.9.008 ◽

2020 ◽

Author(s):

С.А. БАГРЕЦОВ ◽

Э.А. БУДАРИН ◽

О.С. ЛАУТА ◽

М.В. МИТРОФАНОВ

Keyword(s):

Communication Network ◽

Information Flow ◽

Network Traffic ◽

Communication Systems ◽

Reference Network ◽

Computing Systems ◽

Electronic Warfare ◽

Information And Communication ◽

The Stability

Сетевой трафик, проходящий через современные вычислительные системы, представляет собой огромный информационный поток, который содержит сведения различной степени важности. Показана необходимость использования наиболее рациональных приемов повышения устойчивости сети в радиоэлектронной борьбе, чтобы заставить противника затрачивать больше времени на подбор новых принципов воздействия на системы связи. Network traffic passing through modern computing systems is a huge information flow, which contains information of varying degrees of importance. It is shown the necessity of using the most rational methods of increasing the stability of the network in electronic warfare to force the enemy to spend more time on selecting new principles of influence on communication systems.

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