scholarly journals Temporal order of attentional disengagement and reengagement investigated by steady-state visual evoked potentials and event-related potentials

2013 ◽  
Vol 13 (9) ◽  
pp. 1187-1187
Author(s):  
S. Shioiri ◽  
Y. Kashiwase ◽  
N. Omori ◽  
K. Matsumiya ◽  
I. Kuriki
Keyword(s):  
Steady State ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Temporal Order ◽  
Event Related Potentials ◽  
Attentional Disengagement ◽  
Related Potentials ◽  
Visual Evoked

scholarly journals PARIETAL CONTRIBUTIONS TO ABSTRACT NUMEROSITY MEASURED WITH STEADY STATE VISUAL EVOKED POTENTIALS

2020 ◽  
Author(s):  
Peter J. Kohler ◽  
Elham Barzegaran ◽  
Anthony M. Norcia ◽  
Bruce D. McCandliss
Keyword(s):  
Steady State ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Distance Effect ◽  
Event Related Potentials ◽  
Occipital Cortex ◽  
Transient Event ◽  
Related Potentials ◽  
Symbolic Number ◽  
Visual Evoked

AbstractNon-symbolic number changes produce transient Event Related Potentials over parietal electrodes, while numerosity effects measured with Steady-State Visual Evoked Potentials (SSVEPs) appear to originate in occipital cortex. We hypothesized that the stimulation rates used in previous SSVEP studies may be too rapid to drive parietal numerosity mechanisms. Here we recorded SSVEPs and behavioral reports over a slower range of temporal frequencies than previously used. Isoluminant dot stimuli updated at a consistent “carrier” frequency (3-6 Hz) while periodic changes in numerosity (e.g. 8→5) formed an even slower “oddball” frequency (0.5-1 Hz). Each numerosity oddball condition had a matched control condition where the number of dots did not change. Carrier frequencies induced SSVEPs with midline occipital topographies that did not differentiate the presence or absence of numerosity oddballs. By contrast, SSVEPs at oddball frequencies had parietal topographies and responded more strongly when oddballs were present. Consistent with our hypothesis, numerosity effects were stronger at slower stimulation rates. In a second study, the numerosity change was either supra-threshold (e.g. 8→5 dots) or near the threshold required for detecting numerosity changes (e.g. 8→9 dots). We found robust parietal responses for the supra-threshold case only, indicating a numerical distance effect. A third study replicated the parietal oddball SSVEP effect across four distinct suprathreshold numerosity-change conditions and showed that number change direction does not influence the effect. These findings show that SSVEP oddball paradigms can probe parietal computations of abstract numerosity, and may provide a rapid, portable approach to quantifying number sense within educational settings.

scholarly journals Control asíncrono de sistemas BCI basados en ERP mediante la detección de potenciales evocados visuales de estado estable provocados por los estímulos periféricos del paradigma oddball.

2019 ◽  
Author(s):  
Eduardo Santamaría-Vázquez ◽  
Víctor Martínez-Cagigal ◽  
Javier Gomez-Pilar ◽  
Roberto Hornero
Keyword(s):  
Steady State ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Brain Computer Interface ◽  
Event Related Potentials ◽  
Computer Interface ◽  
Calidad De Vida ◽  
El Sistema ◽  
Related Potentials ◽  
Visual Evoked

Los sistemas Brain-Computer Interface (BCI) permiten la comunicación en tiempo real entre el cerebro y el entorno midiendo la actividad neuronal, sin la necesidad de que intervengan músculos o nervios periféricos. En la práctica, normalmente se emplea el electroencefalograma (EEG) para registrar la actividad cerebral, debido a que se realiza con un equipo portable, no invasivo y de bajo coste en comparación con otras técnicas disponibles. Una vez adquirida la señal EEG, esta es analizada en tiempo real por un software que determina las intenciones del usuario y las traduce en comandos de la aplicación, proporcionando una realimentación visual o auditiva. En concreto, los sistemas BCI basados en potenciales relacionados con eventos (event related potentials, ERP) utilizan el llamado paradigma oddball. Este paradigma presenta una matriz de comandos, cuyas filas y columnas se iluminan de manera secuencial. Para seleccionar un comando, el usuario debe mirar a fijamente a la celda correspondiente de la matriz. Los estímulos visuales, percibidos con la región central de su campo visual, provocan un ERP en la señal de EEG. Posteriormente, el sistema determina el comando que quiere seleccionar el usuario mediante la detección de estos ERP. Actualmente, una de las mayores limitaciones de los sistemas BCI basados en ERP es que son inherentemente síncronos. La aplicación selecciona un comando después de un número predefinido de iluminaciones, aunque el usuario no esté atendiendo a los estímulos. Esta limitación restringe el uso de estos sistemas en la vida real, donde los usuarios deberían poder dejar de prestar atención a la aplicación para realizar otras tareas sin que se seleccionen comandos indeseados. Esta característica es especialmente importante en aplicaciones BCI enfocadas al aumento de la calidad de vida de personas con grave discapacidad, como navegadores web o sistemas de control de sillas de ruedas. Para resolver esta limitación, es necesario añadir al sistema un método que detecte en tiempo real si el usuario realmente quiere seleccionar un comando. En este estudio presentamos un novedoso método de asincronía para detectar en tiempo real el estado de control del usuario en los sistemas BCI basados en EPR. Con este objetivo, el sistema detecta los potenciales evocados visuales de estado estable (steady-state visual evoked potentials, SSVEP) provocados por los estímulos periféricos del paradigma oddball. Estas ondas son la respuesta oscilatoria que aparece en la señal de EEG cuando se recibe una estimulación repetitiva a una frecuencia constante. Las iluminaciones periféricas del paradigma oddball provocan un SSVEP a la frecuencia de estimulación, que aparece únicamente cuando el usuario está mirando a la matriz. Por tanto, la detección de esta componente permite determinar si el usuario quiere seleccionar un comando o no. El método propuesto ha sido validado de manera offline con 5 sujetos sanos, alcanzando una precisión media en la detección del estado de control del usuario del 99.7% con 15 secuencias de estimulación. Estos resultados sugieren que esta metodología permite un control asíncrono fiable del sistema BCI, lo que es de gran utilidad en aplicaciones para la mejora de la calidad de las personas con grave discapacidad.

Visual evoked potentials and long latency event-related potentials in chronic renal failure

Neurology ◽  
1983 ◽  
Vol 33 (9) ◽  
pp. 1219-1219 ◽  
Author(s):  
S. N. Cohen ◽  
K. Syndulko ◽  
B. Rever ◽  
J. Kraut ◽  
J. Coburn ◽  
...  
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Event Related Potentials ◽  
Long Latency ◽  
Related Potentials ◽  
Visual Evoked

Event-related potentials in an invertebrate: crayfish emit ‘omitted stimulus potentials’

2001 ◽  
Vol 204 (24) ◽  
pp. 4291-4300
Author(s):  
Fidel Ramón ◽  
Oscar H. Hernández ◽  
Theodore H. Bullock
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Internal State ◽  
Light Flash ◽  
Optic Tract ◽  
Event Related Potentials ◽  
Ambient Light ◽  
Stimulus Interval ◽  
Related Potentials ◽  
Visual Evoked

SUMMARY Electrical signs of neural activity correlated with stimuli or states include a subclass called event-related potentials. These overlap with, but can often be distinguished from, simple stimulus-bound evoked potentials by their greater dependence on endogenous (internal state) factors. Studied mainly in humans, where they are commonly associated with cognition, they are considered to represent objective signs of moderately high-level brain processing. We tested the hypothesis that invertebrates lack such signs by looking in the crayfish Procambarus clarkii for a class of OFF-effects shown in humans to index expectancy. Disproving the hypothesis, we find, using chronic, implanted preparations, that a good omitted stimulus potential is reliably present. The system learns in a few cycles of a regularly repeated light flash to expect one on schedule. Omitted stimulus potentials are found in the protocerebrum, the circumesophageal connective and in the optic tract – perhaps arising in the retina, as in vertebrates. These potentials can be very local and can include loci with and without direct visual evoked potentials in response to each flash. In some loci, the omitted stimulus potential has a slow wave component, in others only a spike burst. Omitted stimulus potentials are more endogenous than visual evoked potentials, with little dependence on flash or ambient light intensity or on train duration. They vary little in size at different times of the day, but abruptly fail to appear if the ambient light is cut off. They can occur during walking, eating or the maintained defense posture but are diminished by ‘distraction’ and are often absent from an inert crayfish until it is aroused. We consider this form of apparent expectation of a learned rhythm (a property that makes it ‘cognitive’ in current usage), to be one of low level, even though some properties suggest endogenous factors. The flashes in a train have an inhibitory effect on a circuit that quickly ‘learns’ the stimulus interval so that the omitted stimulus potential, ready to happen after the learned interval, is prevented by each flash, until released by a missing stimulus.

Electrophysiology in developmental populations: Key methods and findings

2020 ◽  
Author(s):  
Ryan Barry-Anwar ◽  
Tracy Riggins ◽  
Lisa S. Scott
Keyword(s):  
Steady State ◽  
Evoked Potentials ◽  
Human Development ◽  
Visual Evoked Potentials ◽  
Event Related Potentials ◽  
Eeg Signal ◽  
Electrophysiological Studies ◽  
Related Potentials ◽  
Electroencephalogram Eeg ◽  
Electrophysiological Methods

This chapter aims to provide a methodological and empirical overview of electrophysiological techniques used to study human development including: 1) electroencephalogram (EEG), 2) event-related potentials (ERPs), and 3) steady-state visual evoked potentials (ssVEPs). This overview is written to encourage the use of multiple techniques in electrophysiological studies of development. The chapter begins with an introduction to electrophysiological methods and the underlying neural events that give rise to the EEG signal. Second, each technique is described and important electrophysiological empirical contributions to our understanding of development from infancy through childhood and into adolescence are highlighted. Third, considerations and recommendations for the collection, processing, analysis, and publication of developmental electrophysiological data are discussed. Finally, the chapter ends with a look at the future of electrophysiology for the study of development.

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