Visual P300 Stimulator with Non Uniform Background and Non Symmetric Stimulation Markers

Brain–computer interfaces (BCI) are a type of assistive technology that uses the brain signals of users to establish a communication and control channel between them and an external device. BCI systems may be a suitable tool to restore communication skills in severely motor-disabled patients, as BCI do not rely on muscular control. The loss of communication is one of the most negative consequences reported by such patients. This paper presents a BCI system focused on the control of four mainstream messaging applications running in a smartphone: WhatsApp, Telegram, e-mail and short message service (SMS). The control of the BCI is achieved through the well-known visual P300 row-column paradigm (RCP), allowing the user to select control commands as well as spelling characters. For the control of the smartphone, the system sends synthesized voice commands that are interpreted by a virtual assistant running in the smartphone. Four tasks related to the four mentioned messaging services were tested with 15 healthy volunteers, most of whom were able to accomplish the tasks, which included sending free text e-mails to an address proposed by the subjects themselves. The online performance results obtained, as well as the results of subjective questionnaires, support the viability of the proposed system.

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Vortex–Vortex Interactions for the Maintenance of Blocking. Part II: Numerical Experiments

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-12-0132.1 ◽

2013 ◽

Vol 70 (3) ◽

pp. 743-766 ◽

Cited By ~ 5

Author(s):

Akira Yamazaki ◽

Hisanori Itoh

Keyword(s):

Numerical Experiments ◽

Channel Model ◽

Spherical Model ◽

Zonal Flow ◽

Selective Absorption ◽

Absorption Mechanism ◽

Vortex Interactions ◽

Maintenance Mechanism ◽

Uniform Background

Abstract The selective absorption mechanism (SAM), newly proposed in Part I of this study on the maintenance mechanism of blocking, is verified through numerical experiments. The experiments were based on the nonlinear equivalent-barotropic potential vorticity equation, with varying conditions with respect to the shape and amplitude of blocking, and characteristics of storm tracks (displacement and strength) and background zonal flow. The experiments indicate that the SAM effectively maintains blocking, irrespective of the above conditions. At first, by applying a channel model on a β plane, numerical experiments were conducted using a uniform background westerly with and without a jet. The results show that the presence of a jet promotes the effectiveness of the SAM. Then, two types of spherical model experiments were also performed. In idealized experiments, the SAM was as effective as the β-plane model in explaining the maintenance of blocking. Moreover, experiments performed under realistic meteorological conditions showed that the SAM maintained a real block, demonstrating that the SAM is effective. These results, and the case study in Part I, verify that the SAM is the effective general maintenance mechanism for blocking.

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Background Synaptic Activity as a Switch Between Dynamical States in a Network

Neural Computation ◽

10.1162/089976603321891756 ◽

2003 ◽

Vol 15 (7) ◽

pp. 1439-1475 ◽

Cited By ~ 49

Author(s):

Emilio Salinas

Keyword(s):

Random Network ◽

Red Light ◽

Theoretical Models ◽

Reciprocal Inhibition ◽

Synaptic Activity ◽

Dynamic State ◽

Motor Action ◽

Sustained Activity ◽

Uniform Background ◽

Background Input

A bright red light may trigger a sudden motor action in a driver crossing an intersection: stepping at once on the brakes. The same red light, however, may be entirely inconsequential if it appears, say, inside a movie theater. Clearly, context determines whether a particular stimulus will trigger a motor response, but what is the neural correlate of this? How does the nervous system enable or disable whole networks so that they are responsive or not to a given sensory signal? Using theoretical models and computer simulations, I show that networks of neurons have a built-in capacity to switch between two types of dynamic state: one in which activity is low and approximately equal for all units, and another in which different activity distributions are possible and may even change dynamically. This property allows whole circuits to be turned on or off by weak, unstructured inputs. These results are illustrated using networks of integrate-and-fire neurons with diverse architectures. In agreement with the analytic calculations, a uniform background input may determine whether a random network has one or two stable firing levels; it may give rise to randomly alternating firing episodes in a circuit with reciprocal inhibition; and it may regulate the capacity of a center-surround circuit to produce either self-sustained activity or traveling waves. Thus, the functional properties of a network may be drastically modified by a simple, weak signal. This mechanism works as long as the network is able to exhibit stable firing states, or attractors.

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Transient global ischemia specifically modulates visual P300 scalp distribution

Clinical Neurophysiology ◽

10.1016/s1388-2457(00)00480-6 ◽

2000 ◽

Vol 111 (12) ◽

pp. 2245-2254 ◽

Cited By ~ 5

Author(s):

Markus Ullsperger ◽

Axel Mecklinger ◽

Gabi Matthes-von Cramon ◽

D Yves von Cramon

Keyword(s):

Global Ischemia ◽

Scalp Distribution ◽

Transient Global Ischemia ◽

Visual P300

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Reduction of visual P300 during transient global amnesia

Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section ◽

10.1016/0168-5597(94)90019-1 ◽

1994 ◽

Vol 92 (5) ◽

pp. 422-425 ◽

Cited By ~ 10

Author(s):

Hirokazu Bokura ◽

Shuhei Yamaguchi ◽

Haruhisa Tsuchiya ◽

Kazuya Yamashita ◽

Shotai Kobayashi

Keyword(s):

Transient Global Amnesia ◽

Global Amnesia ◽

Visual P300

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The nonlinear electromigration of analytes into confined spaces

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2012.0221 ◽

2012 ◽

Vol 468 (2146) ◽

pp. 3139-3152 ◽

Cited By ~ 3

Author(s):

Zhen Chen ◽

Sandip Ghosal

Keyword(s):

Electric Field ◽

Background Electrolyte ◽

Ionic Transport ◽

Wave Shape ◽

One Dimensional ◽

Sample Concentration ◽

Confined Spaces ◽

Electrokinetic Injection ◽

Sudden Contraction ◽

Uniform Background

We consider the problem of electromigration of a sample ion (analyte) within a uniform background electrolyte when the confining channel undergoes a sudden contraction. One example of such a situation arises in microfluidics in the electrokinetic injection of the analyte into a micro-capillary from a reservoir of much larger size. Here, the sample concentration propagates as a wave driven by the electric field. The dynamics is governed by the Nerst–Planck–Poisson system of equations for ionic transport. A reduced one-dimensional nonlinear equation, describing the evolution of the sample concentration, is derived. We integrate this equation numerically to obtain the evolution of the wave shape and determine how the injected mass depends on the sample concentration in the reservoir. It is shown that due to the nonlinear coupling of the ionic concentrations and the electric field, the concentration of the injected sample could be substantially less than the concentration of the sample in the reservoir.

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Changes in prefrontal cortex near infrared spectroscopy activity as a function of difficulty in a visual P300 paradigm

Journal of Near Infrared Spectroscopy ◽

10.1177/0967033518791320 ◽

2018 ◽

Vol 26 (4) ◽

pp. 222-228 ◽

Cited By ~ 4

Author(s):

Will Rizer ◽

Jacob S Aday ◽

Joshua M Carlson

Keyword(s):

Prefrontal Cortex ◽

Task Difficulty ◽

Near Infrared ◽

Nir Spectroscopy ◽

Event Related Potential ◽

Attentional Resources ◽

Oddball Task ◽

The Right ◽

Visual P300 ◽

P300 Event Related Potential

The P300 event-related potential is an index of attentional resources related to target detection. Source localization and functional magnetic resonance imaging (fMRI) research has indicated that, among other regions, the prefrontal cortex contributes to the generation of the P300. Similar to fMRI, near infrared (NIR) spectroscopy measures change in blood oxygen levels, but offers several advantages including portability, low expense, and superior temporal resolution. No studies to date have examined the extent to which prefrontal cortex NIR spectroscopy measures are active during the P300 paradigm. To address this knowledge gap, participants completed a two-difficulty visual oddball task in which NIR spectroscopy and P300 data were collected in a counterbalanced order. Confirmatory results indicate that the P300 event-related potential is attenuated as a function of task difficulty. Similarly, NIR spectroscopy measures of oxygenated hemoglobin in the right medial prefrontal cortex are attenuated as a function of task difficulty. The results suggest that prefrontal cortex NIR spectroscopy measures are sensitive to task difficulty in a visual P300 oddball task.

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Vector fields created by Fourier transform of video signals

Radioengineering ◽

10.18127/j00338486-202107-17 ◽

2021 ◽

Author(s):

A.V. Bogoslovsky ◽

V.A. Sukharev ◽

I.V. Zhigulina ◽

M.A. Pantyukhin

Keyword(s):

Vector Field ◽

Power Spectrum ◽

Vector Fields ◽

Amplitude Spectrum ◽

Power Spectra ◽

Field Work ◽

Signal Process ◽

Video Signals ◽

Uniform Background ◽

Pixel Brightness

The power spectrum and autocorrelation are widely used in video signals processing. The phase-frequency spectrum contains more information than the amplitude spectrum. However, the amplitude spectrum is used more often in the video signal process. It is possible to combine the advantages of these two spectra to obtain a vector function such as phase-energy spectrum. This spectrum is sensitive even to a small difference in pixel brightness but at the same time it is as stable as the power spectrum. In this paper, we explored the properties of the phase-power spectrum and related amplitude of partials vector field. We showed that phase-power spectrum has conservative as well as solenoidal components and so it creates curl’s vector field. We also found the components of phase-power spectra that contain pixels with a different degree of contrast on the uniform background. We showed the possibility to use solenoidal component of the phase-power vector field to find the circulation (i.e. field work). We concluded that the circulation along any of brightness contour constants, which is symmetrical to the origin, is equal zero. We explored two-dimensional vector field of the phase-power spectrum. Finally, we determined an effect of pixels with different degree of brightness and their relative position to the image’s edges on vector field’s components formation.

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Age-related differences in visual P300 ERP during dual-task postural balance

10.1109/embc46164.2021.9630088 ◽

2021 ◽

Author(s):

Stefano Tortora ◽

Maria Rubega ◽

Emanuela Formaggio ◽

Roberto Di Marco ◽

Stefano Masiero ◽

...

Keyword(s):

Dual Task ◽

Postural Balance ◽

Age Related ◽

Visual P300

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