scholarly journals Virtual electrodes generated by focused penta‐polar current stimulation for neuromodulation

2020 ◽  
Vol 15 (6) ◽  
pp. 374-377
Author(s):  
Shinyong Shim ◽  
Jeong Hoan Park ◽  
Sung June Kim
Keyword(s):  
Virtual Electrodes

Multi-Angular Electroretinography (maERG): Topographic mapping of the retinal function combining real and virtual electrodes

2021 ◽  
pp. 1-1
Author(s):  
Mercedes Gauthier ◽  
Antoine Brassard-Simard ◽  
Mathieu Gauvin ◽  
Pierre Lachapelle ◽  
Jean-Marc Lina
Keyword(s):  
Retinal Function ◽  
Topographic Mapping ◽  
Virtual Electrodes

scholarly journals VirtEl - Software for Magnetic Encephalography Data Analysis by the Method of Virtual Electrodes

2019 ◽  
Vol 14 (1) ◽  
pp. 340-354 ◽  
Author(s):  
S.D. Rykunov ◽  
E.D. Rykunova ◽  
A.I. Boyko ◽  
M.N. Ustinin
Keyword(s):  
Time Series ◽  
Brain Area ◽  
Three Dimensional ◽  
Large Radius ◽  
Magnetic Encephalography ◽  
Electrode Method ◽  
The Fourier Transform ◽  
Virtual Electrodes ◽  
The Brain ◽  
Virtual Electrode

A new method of analyzing magnetic encephalography data, the virtual electrode method, was developed. According to magnetic encephalography data, a functional tomogram is constructed — the spatial distribution of field sources on a discrete grid. A functional tomogram displays on the head space the information contained in the multichannel time series of an encephalogram. This is achieved by solving the inverse problem for all elementary oscillations extracted using the Fourier transform. Each oscillation frequency corresponds to a three-dimensional grid node in which the source is located. The user sets the location, size and shape of the brain area for a detailed study of the frequency structure of a functional tomogram - a virtual electrode. The set of oscillations that fall into a given region represents the partial spectrum of this region. The time series of the encephalogram measured by the virtual electrode is restored using this spectrum. The method was applied to the analysis of magnetic encephalography data in two variations - a virtual electrode of a large radius and a point virtual electrode.

scholarly journals Development of an anatomically detailed MRI-derived rabbit ventricular model and assessment of its impact on simulations of electrophysiological function

2010 ◽  
Vol 298 (2) ◽  
pp. H699-H718 ◽  
Author(s):  
Martin J. Bishop ◽  
Gernot Plank ◽  
Rebecca A. B. Burton ◽  
Jürgen E. Schneider ◽  
David J. Gavaghan ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Complex Model ◽  
Patient Specific ◽  
Small Scale ◽  
Data Simulation ◽  
Simplified Models ◽  
Anatomical Features ◽  
Patient Specific Modeling ◽  
Rule Based Approach ◽  
Virtual Electrodes

Recent advances in magnetic resonance (MR) imaging technology have unveiled a wealth of information regarding cardiac histoanatomical complexity. However, methods to faithfully translate this level of fine-scale structural detail into computational whole ventricular models are still in their infancy, and, thus, the relevance of this additional complexity for simulations of cardiac function has yet to be elucidated. Here, we describe the development of a highly detailed finite-element computational model (resolution: ∼125 μm) of rabbit ventricles constructed from high-resolution MR data (raw data resolution: 43 × 43 × 36 μm), including the processes of segmentation (using a combination of level-set approaches), identification of relevant anatomical features, mesh generation, and myocyte orientation representation (using a rule-based approach). Full access is provided to the completed model and MR data. Simulation results were compared with those from a simplified model built from the same images but excluding finer anatomical features (vessels/endocardial structures). Initial simulations showed that the presence of trabeculations can provide shortcut paths for excitation, causing regional differences in activation after pacing between models. Endocardial structures gave rise to small-scale virtual electrodes upon the application of external field stimulation, which appeared to protect parts of the endocardium in the complex model from strong polarizations, whereas intramural virtual electrodes caused by blood vessels and extracellular cleft spaces appeared to reduce polarization of the epicardium. Postshock, these differences resulted in the genesis of new excitation wavefronts that were not observed in more simplified models. Furthermore, global differences in the stimulus recovery rates of apex/base regions were observed, causing differences in the ensuing arrhythmogenic episodes. In conclusion, structurally simplified models are well suited for a large range of cardiac modeling applications. However, important differences are seen when behavior at microscales is relevant, particularly when examining the effects of external electrical stimulation on tissue electrophysiology and arrhythmia induction. This highlights the utility of histoanatomically detailed models for investigations of cardiac function, in particular for future patient-specific modeling.

Creating virtual electrodes with 2D current steering

2018 ◽  
Vol 15 (3) ◽  
pp. 035002 ◽  
Author(s):  
Thomas C Spencer ◽  
James B Fallon ◽  
Mohit N Shivdasani
Keyword(s):  
Current Steering ◽  
Virtual Electrodes

Shock-induced virtual electrodes inside the myocardial wall

Heart Rhythm ◽  
2005 ◽  
Vol 2 (5) ◽  
pp. S141-S142
Author(s):  
Christian W. Zemlin ◽  
Sergey F. Mironov ◽  
Arkady M. Pertsov
Keyword(s):  
Myocardial Wall ◽  
Virtual Electrodes

The neural basis of the right visual field advantage in reading: An MEG analysis using virtual electrodes

2011 ◽  
Vol 118 (3) ◽  
pp. 53-71 ◽  
Author(s):  
Laura Barca ◽  
Piers Cornelissen ◽  
Michael Simpson ◽  
Uzma Urooj ◽  
Will Woods ◽  
...  
Keyword(s):  
Visual Field ◽  
Right Visual Field ◽  
Neural Basis ◽  
The Right ◽  
Virtual Electrodes

Biological Applications of Programmable Optoelectrofluidic Manipulation

2009 ◽  
Vol 1173 ◽  
Author(s):  
Je-Kyun Park
Keyword(s):  
Liquid Crystal Display ◽  
Particle Diameter ◽  
Discrimination Performance ◽  
Local Concentration ◽  
Display Device ◽  
Ac Electroosmosis ◽  
Friction Forces ◽  
Ac Electrokinetics ◽  
Virtual Electrodes

AbstractThis paper presents a new programmable particle manipulation using a lab-on-a-display platform, which is a kind of optoelectrofluidic platform applying a liquid crystal display (LCD) as a display device for generating virtual electrodes in optoelectronic tweezers. The reconfigurable virtual electrodes in the lab-on-a-display are more advantageous than other devices which apply the micro-patterned electrodes, because we can freely control the size and position of electrodes as well as the voltage conditions, which affect the particle movements such as concentration and separation of particles. Due to its simple structures, cheap manufacturing costs, and high performances, this new LCD-based optoelectrofluidic platform can be applied to the interactive manipulation of polystyrene microspheres and blood cells. In addition, a method to discriminate normal oocytes for in vitro fertilization is demonstrated by combining the gravity effect with the optically induced positive dielectrophoresis (DEP). The discrimination performance can be enhanced due to the reduction of friction forces acting on the oocytes which are relatively large and heavy cells being affected by the gravity field. With the same device, we also demonstrate the size-dependent microparticle separation as well as the local concentration and assembly of microparticles originated from the image-driven AC electrokinetics such as DEP and AC electroosmosis. The particle movements result from the frequency-dependent behavior according to the particle diameter. This novel technique can be applied to rapidly concentrate, separate and pattern micro-/nanoparticles and biomolecules in many biological and chemical applications.

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