LRH fue apoyada por la Ciencias e Ingeniería de Investigación Natural (NSERC), de Canadá. SD fue apoyado en parte por el programa de NSERC CREATE.

Todos los experimentos fueron aprobados por el comité de ética York y todos los participantes firmaron formularios de consentimiento informado. Los experimentos se realizaron de acuerdo con el Tratado de Helsinki. 1. Los estímulos <ol><li> Estímulo de detección táctiles <ol><li> Use un contactor (1.17 &quot;de diámetro y 0.30&quot; de espesor) para entregar estímulos táctiles de la vibración 250 Hz durante 100 ms. El uso de un contactor especialmente diseñada ofrece una relación lineal entre la cantidad de viajes y el voltaje aplicado. </li><li> Controlar el suministro de estímulo táctil con una tarjeta de sonido de 64 bits. <ol><li> Para conducir el contactor, lo tratan como un altavoz. Conectar un amplificador de audio estéreo a una tarjeta de sonido estéreo equipo de 64 bits. Conectar el contactor a una de las salidas del amplificador (por ejemplo, la &quot;izquierda altavoz hacia fuera &#39;). Conectar el segundo canal (por ejemplo, el &quot;altavoz derecho a cabo &#39;) del amplificador a un altavoz regular para proporcionar señales auditivas a la parpante. </li><li> En el código de ordenador que controla el experimento, generar la forma de onda que se utilizará para hacer vibrar el contactor (por ejemplo, una onda sinusoidal de 250 Hz de la duración de 100 ms), y otra forma de onda para la señal de sonido (por ejemplo, una onda sinusoidal 3000 Hz con una duración de 100 ms). Véase el ejemplo de código 1 en el archivo de código suplementario. </li><li> Ponga cada una de estas dos formas de onda en una matriz de dos dimensiones. Para la matriz contactor poner la señal en la primera dimensión y establecer la segunda dimensión a todos los ceros. Para la matriz de sonido poner la señal en la segunda dimensión y establecer el primero en todos los ceros. Juega la matriz adecuada para la tarjeta de sonido en el punto apropiado en el programa. Véase el ejemplo de código 1 en el archivo de código suplementario para una demostración de cómo se hace esto. </li></ol></li><li> Acople el contactor a una correa de sujeción con un producto basado en la mecánica. </li></ol></li><li> estímulo de enmascaramiento <ol><li> Proporcionar el estímulo de enmascaramiento por una eléctrica, jand-sostenido (4 cm de diámetro; 83 Hz cuando se encuentra en &quot;baja&quot;) vibrador. </li><li> Sobre la base de las áreas en las que el enmascaramiento se va a probar, seleccionar los sitios en los que el estímulo de enmascaramiento se va a aplicar. </li></ol></li></ol> 2. Configuración Experimental y Diseño <ol><li> Disponga el equipo y el equipo en un escritorio, una silla frente a ella, por el experimentador. </li><li> Establecer una mesa sobre la que descansan los participantes su brazo (prueba) a la izquierda. Coloque una silla para el lado derecho de la tabla. Ponga un stand reposabrazos al lado de la silla en la que los participantes descansar el codo (enmascaramiento brazo) derecha. Añadir amortiguación a la mesa y apoyabrazos para una mayor comodidad. </li><li> Organizar un altavoz en una superficie mecánicamente aislado. Organizar pedales (conectado a los botones izquierdo y derecho de un ratón de ordenador), de modo que los pies de los participantes van a descansar cómodamente en ellos (Figura 1). </li><li> Elija los parámetros del estudio, incluyendo el número apropiado de ensayos requeridospara obtener una estimación fiable del umbral (típicamente, entre 40 a 50 ensayos) y el número de bloques en el que el experimento se va a dividir (por ejemplo, dos bloques de 20-25 ensayos por condición). </li><li> Haga una lista de la orden en el que se ejecutarán las condiciones. Utilice esta lista para determinar dónde llevar a cabo el estímulo de enmascaramiento para cada bloque. </li><li> Introduce el número de ensayos directamente en el código de programa de ordenador (por ejemplo, ntrials = 25; Ver archivo de código suplementario). Asegúrese de que cada bloque ya no es de 10 minutos para mantener la atención. </li><li> Programar una forzada de dos alternativas de opción-tarea de detección táctil 11 en el que la intensidad del estímulo se controla con un procedimiento psicométrica escalera psicofísica adaptativo bayesiano 12. <ol><li> Para cada ensayo, presentes dos intervalos de 1 segundo, marcado por tres pitidos (5 kHz, 3 kHz y 5 kHz, duración de 100 ms), con el estímulo táctil presentado en medio de uno de los intervalos. Tener el participante indicate intervalo en el que el estímulo fue presentado por medio de pedales (de izquierda para el primer, segundo por la derecha). Ver Ejemplo de código 2, que muestra cómo los intervalos se ejecutan y se anotó. Nota: Las calificaciones de ordenador como la respuesta &quot;correcta&quot; o &quot;incorrecta&quot; y la escalera de adaptación selecciona el siguiente valor que se presentará en consecuencia. Nota: Este método determina un valor umbral para la detección de la vibración en el sitio de prueba. </li></ol></li></ol><img alt="Figura 1" src="/files/ftp_upload/53733/53733fig1.jpg" /> Figura 1. Diseño experimental. Esta figura muestra la puesta en marcha del experimento y los materiales utilizados. Véase el texto para más detalles. 3. Procedimiento experimental <ol><li> Obtener el consentimiento informado por escrito. Asentar el participante en la silla con sus pies descansando cómodamente en los pedales de respuesta y explicar el procedimiento experimental. &lt;/ Li&gt; <li> Medir y registrar la longitud de la superficie dorsal del antebrazo izquierdo. Aplicar la correa de modo que el contactor se coloca en el medio de la mitad del brazo entre el ángulo interno del codo y el pliegue de la muñeca. </li><li> Envolver un vendaje tensor libremente alrededor del brazo varias veces para mantener el contactor en su lugar. </li><li> Instruir a los participantes a poner su brazo izquierdo sobre la mesa y descansar su codo derecho en el reposabrazos. Venda de los ojos del participante para evitar que mirar el estímulo o enmascarar lugar y darles instrucciones para mirar hacia adelante a lo largo del experimento. </li><li> Comience con un bloque de 20 ensayos de práctica (sin el estímulo de enmascaramiento) con el fin de familiarizar a los participantes con la tarea de detección táctil y que les permita familiarizarse con los estímulos táctiles. </li><li> A raíz de los ensayos de práctica, comenzar el experimento, la ejecución de los bloques de condiciones en un orden aleatorio, con contrapeso. Antes de comenzar cada bloque, garantizar que las armas y el enmascaramiento Stimulus están en las posiciones correctas. <ol><li> Para cada condición, mantenga el estímulo de enmascarar en el sitio elegido, en referencia a la lista de las condiciones anteriores. Tachar cada condición en que se ejecuta. Mantenga el estímulo de enmascarar lo largo de cada bloque de ensayos de recogida de datos se mantiene la presión aproximadamente constante. El estímulo de enmascaramiento se puede aplicar a través de la tela delgada. </li><li> Ejecutar el programa experimental que se desarrollará a través de un número determinado de intentos, lo que previamente seleccionada. Introducir un período de descanso de 2 minutos después de cada secuencia corta de los ensayos. Después de que se complete un bloque determinado de ensayos, seleccione el siguiente sitio para el estímulo de enmascaramiento y ejecutar el programa de nuevo. Repita hasta que se hayan completado todos los ensayos. </li></ol></li></ol> Análisis 4. Datos <ol><li> Para visualizar y confirmar la estimación del valor de umbral devuelto por el programa de escalera de adaptación 12, ajustar los datos de los participantes con una gaussiana acumulativa La fórmula para una gaussiana acumulativa(Sigmoide) que va desde el 50% (nivel de azar - igual número de 0s - mal y 1&#39;s- correcta) a 100% (todo de 1, los correctos) es: probabilidad de una respuesta correcta = 0,5 + 0,5 / (1 + exp (- (x-x0) / std)) donde x es el valor de la intensidad probado, x0 es el valor umbral de 75%, y std es la desviación estándar de la estimación. Esta fórmula se puede ajustar a los datos utilizando el software de ajuste de curvas y el valor x0 resultante en comparación con el valor adaptativo escalera. <ol><li> Asegúrese de que la curva va entre 50% (rendimiento de probabilidad) y 100%. Llevar a cabo análisis estadísticos (por ejemplo, pruebas t o ANOVA) en los valores umbral del 75% obtenidos en cada condición del experimento (por ejemplo, entre los diferentes sitios de enmascaramiento) para determinar si hay diferencias entre las condiciones ensayadas. </li></ol></li><li> Con el fin de identificar los valores atípicos, calcular la media y la desviación estándar para una condición dada. Comparar la puntuación de cada participante con la media y lasi una puntuación individual es más de 2 desviación estándar a partir de ese entonces significa considerar esta partitura como un valor atípico y sacarlo del análisis. Criterios alternativos se pueden usar si se desea. </li><li> Para estandarizar los valores de la intensidad de los contactores (que están en en unidades arbitrarias), las convierten en decibelios con relación a los umbrales de control (medidos cuando el estímulo de enmascaramiento se aplica al sitio de control, por ejemplo, el hombro). Utilice esta fórmula: dB = 10 x log 10 (valor umbral de valor umbral / control). </li></ol>

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Los autores declaran que no tienen intereses financieros en competencia.

Aquí, se describe un protocolo detallado para el enmascaramiento táctil contralateral y los resultados publicados anteriormente utilizando la técnica de poner a prueba los umbrales de detección táctiles se muestran. La ventaja de este método es que los umbrales se miden utilizando una técnica psychophysically riguroso. La elección forzada procedimiento de dos alternativa (2AFC) es relativamente insensible a sesgo de respuesta y por lo tanto de los efectos de atención. El procedimiento escalera de adaptación pa...

enmascaramiento táctil es donde un estímulo táctil en un lugar en el cuerpo altera la percepción de un toque en otro lugar. Esta es una técnica por primera vez por von Békésy 1 para revelar interacciones ubicación, especialmente la inhibición lateral, entre las zonas de la piel que son adyacentes en la superficie del cuerpo. Mientras enmascaramiento táctil se ha estudiado ampliamente en los últimos años, la investigación ha investigado sobre todo enmascaramiento ipsilateral táctil mediante la estimulación eléctrica 2, 3, 4 presión, y la estimulación vibrotáctil 5, 6. Por el contrario, pocos estudios han examinado el enmascaramiento contralateral táctil en la que los sitios de enmascaramiento y las sondas pueden ser quitados lejos. De largo alcance efectos de enmascaramiento táctiles se han mostrado entre los puntos de simetría de espejo en la mano y el brazo 5, 7 - 9, pero estos estudios se han limitado en gran medida a mirar las manos y los dedos 7, 10, con más extensas partes de todo el cuerpo está en gran medida ignorados. Uno de los objetivos de tales experimentos de enmascaramiento de largo alcance es indicar cómo los componentes de la representación del cuerpo en el cerebro pueden estar relacionados funcionalmente. Aquí, el fenómeno de largo alcance enmascaramiento táctil es explorado por la investigación de cómo la vibración aplicada a un antebrazo podría afectar umbrales de sensibilidad táctil en el antebrazo opuesto. Umbral se refiere al estímulo mínimo que se necesita para detectar un estímulo. Definimos esto como la intensidad a la que se detecta el estímulo 75% del tiempo. Se utilizó una técnica de enmascaramiento táctil en la que la sensibilidad táctil (el recíproco de umbral) en un antebrazo se mide en la presencia de un estímulo vibratorio (la máscara) en otra parte del cuerpo. Enmascaramiento efectivo es revelado por un aumento en el umbral de detección es decir, una reducción de la sensibilidad. La técnica se puede utilizar en combinación con otras manipulaciones tales como variando posición de las extremidades or movimiento para explorar sus efectos sobre la eficacia de enmascaramiento. Aquí hemos utilizado estímulos vibrotactile como el estímulo de enmascaramiento. La ventaja de esto es que la frecuencia, y por lo tanto el tipo de receptor que estimula pueden ser controlados. La técnica podría extenderse a mirar dolor utilizando estímulos eléctricos como la sonda o máscara o ambos. También, cualquier sitio puede utilizarse como el sitio de enmascaramiento que permite la investigación de los sitios de acupuntura por ejemplo.

<table><tbody><tr><td>C-2 tactor</td><td>ATAC Technology; Engineering Acoustics, Inc.</td><td></td><td>http://www.atactech.com/PR_tactors.html</td></tr><tr><td>Magic Wand</td><td>Hitachi</td><td></td><td>http://magicwandoriginal.com/magic-wand-original/</td></tr><tr><td>FC5 Foot Pedals</td><td>Yamaha Corporation</td><td></td><td>http://ca.yamaha.com/en/products/music-production/accessories/footpedals/fc5/?mode=model</td></tr><tr><td>MATLAB</td><td>The Mathworks, Inc.</td><td></td><td>http://www.mathworks.com/products/matlab/</td></tr><tr><td>Velcro</td><td>Velcro Industries B.V.</td><td></td><td>http://www.velcro.com/</td></tr></tbody></table>

testing tactile masking between the forearms

Masking, in which one stimulus affects the detection of another, is a classic technique that has been used in visual, auditory, and tactile research, usually using stimuli that are close together to reveal local interactions. Masking effects have also been demonstrated in which a tactile stimulus alters the perception of a touch at a distant location. Such effects can provide insight into how components of the body's representations in the brain may be linked. Occasional reports have indicated that touches on one hand or forearm can affect tactile sensitivity at corresponding contralateral locations. To explore the matching of corresponding points across the body, we can measure the spatial tuning and effect of posture on contralateral masking. Careful controls are required to rule out direct effects of the remote stimulus, for example by mechanical transmission, and also attention effects in which thresholds may be altered by the participant's attention being drawn away from the stimulus of interest. The use of this technique is beneficial as a behavioural measure for exploring which parts of the body are functionally connected and whether the two sides of the body interact in a somatotopic representation. This manuscript describes a behavioural protocol that can be used for studying contralateral tactile masking.

Los análisis de los datos se informaron en el 13. Sensibilidad táctil (expresado en relación con los umbrales medidos en la condición de control) en el antebrazo se redujo significativamente (umbrales se incrementaron significativamente) cuando la estimulación vibrotáctil enmascaramiento se aplicó al brazo opuesto (figura 2A), lo que demuestra un efecto de enmascaramiento contralateral entre antebrazos. El efecto dependía de la posición del estímulo ...

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Testing Tactile Masking between the Forearms

Las pruebas táctil enmascaramiento entre los antebrazos

Here we explore contralateral tactile masking between the forearms in which tactile detection thresholds are modulated by vibration applied to a remote site. The details of which remote sites have an effect can tell us about how the body is represented in the brain.

Masking, in which one stimulus affects the detection of another, is a classic technique that has been used in visual, auditory, and tactile research, ...

testing-tactile-masking-between-the-forearms

Research

JoVE Journal

Behavior

6.3K vistas.  York University. Here we explore contralateral tactile masking between the forearms in which tactile detection thresholds are modulated by vibration applied to a remote site. The details of which remote sites have an effect can tell us about how the body is represented in the brain. 

Video: Testing Tactile Masking between the Forearms

The Crossmodal Congruency Task as a Means to Obtain an Objective Behavioral Measure in the Rubber Hand Illusion Paradigm

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden hand is touched. If the viewed and felt touches are given at the same time then this is sufficient to induce the compelling experience that the rubber hand is one's own hand. The RHI can be used to investigate exactly how the brain constructs distinct body representations for one's own body. Such representations are crucial for successful interactions with the external world. To obtain a subjective measure of the RHI, researchers typically ask participants to rate statements such as "I felt as if the rubber hand were my hand". Here we demonstrate how the crossmodal congruency task can be used to obtain an objective behavioral measure within this paradigm.
The variant of the crossmodal congruency task we employ involves the presentation of tactile targets and visual distractors. Targets and distractors are spatially congruent (i.e. same finger) on some trials and incongruent (i.e. different finger) on others. The difference in performance between incongruent and congruent trials - the crossmodal congruency effect (CCE) - indexes multisensory interactions. Importantly, the CCE is modulated both by viewing a hand as well as the synchrony of viewed and felt touch which are both crucial factors for the RHI.
The use of the crossmodal congruency task within the RHI paradigm has several advantages. It is a simple behavioral measure which can be repeated many times and which can be obtained during the illusion while participants view the artificial hand. Furthermore, this measure is not susceptible to observer and experimenter biases. The combination of the RHI paradigm with the crossmodal congruency task allows in particular for the investigation of multisensory processes which are critical for modulations of body representations as in the RHI.

We demonstrate how an objective measure can be employed in the widely employed rubber hand illusion paradigm. This measure is obtained by modifying the well-established crossmodal congruency task. This task allows the investigation of multisensory processes which are critical for modulations of body representations as in the rubber hand illusion.

El Grupo de Congruencia crossmodal como medio para obtener una medida del comportamiento objetivo de la Guía Caucho mano Illusion Paradigm

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden ...

Investigación

Comportamiento

Creating Virtual-hand and Virtual-face Illusions to Investigate Self-representation

Studies investigating how people represent themselves and their own body often use variants of &#34;ownership illusions&#34;, such as the traditional rubber-hand illusion or the more recently discovered enfacement illusion. However, these examples require rather artificial experimental setups, in which the artificial effector needs to be stroked in synchrony with the participants&#39; real hand or face&#8212;a situation in which participants have no control over the stroking or the movements of their real or artificial effector. Here, we describe a technique to establish ownership illusions in a setup that is more realistic, more intuitive, and of presumably higher ecological validity. It allows creating the virtual-hand illusion by having participants control the movements of a virtual hand presented on a screen or in virtual space in front of them. If the virtual hand moves in synchrony with the participants&#39; own real hand, they tend to perceive the virtual hand as part of their own body. The technique also creates the virtual-face illusion by having participants control the movements of a virtual face in front of them, again with the effect that they tend to perceive the face as their own if it moves in synchrony with their real face. Studying the circumstances that illusions of this sort can be created, increased, or reduced provides important information about how people create and maintain representations of themselves.

Here, we describe virtual-hand and virtual-face illusion paradigms that can be used to study body-related self-perception/-representation. They have already been used in various studies to demonstrate that, under specific conditions, a virtual hand or face can be incorporated into one&#39;s body representation, suggesting that body representations are rather flexible.

Creando ilusiones virtual a mano y Virtual-cara de investigar las auto-representación

Studies investigating how people represent themselves and their own body often use variants of &#34;ownership illusions&#34;, such as the traditional ...

Using Facial Electromyography to Assess Facial Muscle Reactions to Experienced and Observed Affective Touch in Humans

"Affective" touch is believed to be processed in a manner distinct from discriminatory touch and to involve activation of C-tactile (CT) afferent fibers. Touch that optimally activates CT fibers is consistently rated as hedonically pleasant. Patient groups with impaired social-emotional functioning also show disordered affective touch ratings. However, relying on self-reported ratings of touch has many limitations, including recall bias and communication barriers. Here, we describe a methodological approach to study affective responses to touch via facial electromyography (EMG) that circumvents the reliance on self-report ratings. Facial EMG is an objective, quantitative, and non-invasive method to measure facial muscle activity indicative of affective responses. Responses can be assessed across healthy and patient populations without the need for verbal communication. Here, we provide two separate datasets demonstrating that CT-optimal and non-optimal touch elicit distinct facial muscle reactions. Moreover, facial EMG responses are consistent across stimulus modalities, e.g. tactile (experienced touch) and visual (observed touch). Finally, the temporal resolution of facial EMG can detect responses on timescales that supersede that of verbal reporting. Together, our data suggest that facial EMG is a suitable methodology for use in affective tactile research that can be used to supplement, or in some cases, supplant, existing measures.

We describe a protocol to assess facial muscle activity in response to experienced and observed tactile stimulation using facial electromyography.

Usando la electromiografía Facial para evaluar las reacciones del músculo Facial tacto afectivo experimentado y observado en los seres humanos

"Affective" touch is believed to be processed in a manner distinct from discriminatory touch and to involve activation of C-tactile (CT) afferent fibers. ...

Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback

The application of incongruent sensory signals that involves disrupted tactile feedback is rarely explored, specifically with the presence of vibrotactile feedback (VTF). This protocol aims to test the effect of VTF on the response to incongruent visual-tactile stimuli. The tactile feedback is acquired by grasping a block and moving it across a partition. The visual feedback is a real-time virtual presentation of the moving block, acquired using a motion capture system. The congruent feedback is the reliable presentation of the movement of the block, so that the subject feels that the block is grasped and see it move along with the path of the hand. The incongruent feedback appears as the movement of the block diverts from the actual movement path, so that it seems to drop from the hand when it is actually still held by the subject, thereby contradicting the tactile feedback. Twenty subjects (age 30.2 &#177; 16.3) repeated 16 block transfers, while their hand was hidden. These were repeated with VTF and without VTF (total of 32 block transfers). Incongruent stimuli were presented randomly twice within the 16 repetitions in each condition (with and without VTF). Each subject was asked to rate the difficulty level of performing the task with and without the VTF. There were no statistically significant differences in the length of the hand paths and durations between transfers recorded with congruent and incongruent visual-tactile signals &#8211; with and without the VTF. The perceived difficulty level of performing the task with the VTF significantly correlated with the normalized path length of the block with VTF (r = 0.675, p = 0.002). This setup is used to quantify the additive or reductive value of VTF during motor function that involves incongruent visual-tactile stimuli. Possible applications are prosthetics design, smart sport-wear, or any other garments that incorporate VTF.

We present a protocol to apply incongruent visual-tactile stimuli during an object transfer task. Specifically, during block transfers, performed while the hand is hidden, a virtual presentation of the block shows random occurrences of false block drops. The protocol also describes adding vibrotactile feedback while performing the motor task.

Aplicación de estímulos visuales-táctiles incongruentes durante la transferencia de objetos con retroalimentación Vibro-táctil

The application of incongruent sensory signals that involves disrupted tactile feedback is rarely explored, specifically with the presence of vibrotactile ...

A Tactile Automated Passive-Finger Stimulator (TAPS)

Although tactile spatial acuity tests are used in both neuroscience research and clinical assessment, few automated devices exist for delivering controlled spatially structured stimuli to the skin. Consequently, investigators often apply tactile stimuli manually. Manual stimulus application is time consuming, requires great care and concentration on the part of the investigator, and leaves many stimulus parameters uncontrolled. We describe here a computer-controlled tactile stimulus system, the Tactile Automated Passive-finger Stimulator (TAPS), that applies spatially structured stimuli to the skin, controlling for onset velocity, contact force, and contact duration. TAPS is a versatile, programmable system, capable of efficiently conducting a variety of psychophysical procedures. We describe the components of TAPS, and show how TAPS is used to administer a two-interval forced-choice tactile grating orientation test.
Corresponding Author: Daniel Goldreich

A Tactile Automated Passive-Finger Stimulator TAPS

We describe a computer-controlled device for investigating the sense of touch: the Tactile Automated Passive-finger Stimulator (TAPS). We describe the components of TAPS, and show how TAPS is used to administer a two-interval forced-choice tactile grating orientation test.

A táctil automático pasivo-Finger Stimulator (TAPS)

Although tactile spatial acuity tests are used in both neuroscience research and clinical assessment, few automated devices exist for delivering ...

Biología

Tactile Semiautomatic Passive-Finger Angle Stimulator (TSPAS)

Passive tactile perception is the ability to passively and statically perceive stimulus information coming from the skin; for example, the ability to sense spatial information is the strongest in the skin on the hands. This ability is termed tactile spatial acuity, and is measured by the tactile threshold or discrimination threshold. At present, the two-point threshold is extensively used as a measure of tactile spatial acuity, although many studies have indicated that critical deficits exist in two-point discrimination. Therefore, a computer-controlled tactile stimulus system was developed, the tactile semiautomated passive-finger angle stimulator (TSPAS), using the tactile angle discrimination threshold as a new measure for tactile spatial acuity. The TSPAS is a simple, easily operated system that applies raised angle stimuli to a subject&#39;s passive fingerpad, while controlling movement speed, distance, and contact duration. The components of the TSPAS are described in detail as well as the procedure to calculate the tactile angle discrimination threshold.

Tactile Semiautomatic Passive-Finger Angle Stimulator TSPAS

Presented is the tactile semiautomated passive-finger angle stimulator TSPAS, a new way to assess tactile spatial acuity and tactile angle discrimination using a computer-controlled tactile stimulus system that applies raised angle stimuli to a subject&#39;s passive fingerpad, while controlling for movement speed, distance, and contact duration.

Estimulador de ángulo de dedo pasivo semiautomático táctil (TSPAS)

Passive tactile perception is the ability to passively and statically perceive stimulus information coming from the skin; for example, the ability to ...

Virtual Hand with Ambiguous Movement between the Self and Other Origin: Sense of Ownership and 'Other-Produced' Agency

The feeling that a body part is one&#8217;s own body (sense of ownership; SoO) and the feeling based on the causal relationship between one&#8217;s will and action (sense of agency; SoA) have been recognized as the basis of our bodily self-consciousness. Previously, the illusory SoO over a fake body part (e.g., rubber hand) was introduced as the rubber hand illusion (RHI). Furthermore, it was determined that one could also evoke a SoA over an object with movements linked to the one&#8217;s prior intention. On the other hand, the postdictivity of our spontaneity implies that it is essentially inseparable whether actions originate from self or others. In other words, our SoA or daily experiences are obtained in such as inseparable scenario. Previous research, however, has maintained the premise that self- and other-origin movements are perceptually distinguishable. Here, we implement a protocol to make these aspects ambiguous for the participants and to estimate whether they can feel SoO and/or SoA and how. To this end, we employ an experiment using virtual reality, under which participants observe virtual fingers moving very slowly (or quickly or not moving) while their own fingers do not move. For evaluation of the illusory SoO, measurements of skin conductance responses against a knife threat are adopted. Additionally, we introduce face-to-face interviews to determine whether the feelings regarding the slow movement match the conventional SoA definition. Our representative results suggest that the SoO is evoked over the hand, and various attitudes to accept its movement as the participant&#8217;s own with awareness that they did not originate it are reported by the majority. As the results show, the novelty of this protocol is discovering that in such a situation, the SoO cooperates with an externally produced SoA to establish one&#8217;s own bodily experience rather than the independence of the SoO and SoA.

While previous research on bodily self-consciousness assumed that self- and other-origin movements were perceptually distinguishable, this protocol allows them to be ambiguous on a virtual hand with unintentional slight movements. This enables us to observe one&#8217;s experience formed by SoO and other-produced SoA, rather than the absence of SoA.

Mano virtual con movimiento ambiguo entre el yo y otro origen: sentido de propiedad y agencia 'producida por otros'

The feeling that a body part is one&#8217;s own body (sense of ownership; SoO) and the feeling based on the causal relationship between one&#8217;s will ...

Estimation of Contact Regions Between Hands and Objects During Human Multi-Digit Grasping

To grasp an object successfully, we must select appropriate contact regions for our hands on the surface of the object. However, identifying such regions is challenging. This paper describes a workflow to estimate the contact regions from marker-based tracking data. Participants grasp real objects, while we track the 3D position of both the objects and the hand, including the fingers' joints. We first determine the joint Euler angles from a selection of tracked markers positioned on the back of the hand. Then, we use state-of-the-art hand mesh reconstruction algorithms to generate a mesh model of the participant's hand in the current pose and the 3D position. 
Using objects that were either 3D printed or 3D scanned-and are, thus, available as both real objects and mesh data-allows the hand and object meshes to be co-registered. In turn, this allows the estimation of approximate contact regions by calculating the intersections between the hand mesh and the co-registered 3D object mesh. The method may be used to estimate where and how humans grasp objects under a variety of conditions. Therefore, the method could be of interest to researchers studying visual and haptic perception, motor control, human-computer interaction in virtual and augmented reality, and robotics.

When we grasp an object, multiple regions of the fingers and hand typically make contact with the object's surface. Reconstructing such contact regions is challenging. Here, we present a method for approximately estimating the contact regions by combining marker-based motion capture with existing deep learning-based hand mesh reconstruction.

Estimación de las regiones de contacto entre las manos y los objetos durante el agarre humano de varios dígitos

To grasp an object successfully, we must select appropriate contact regions for our hands on the surface of the object. However, identifying such regions ...

Non-Invasive Modulation and Robotic Mapping of Motor Cortex in the Developing Brain

Mapping the motor cortex with transcranial magnetic stimulation (TMS) has potential to interrogate motor cortex physiology and plasticity but carries unique challenges in children. Similarly, transcranial direct current stimulation (tDCS) can improve motor learning in adults but has only recently been applied to children. The use of tDCS and emerging techniques like high&#8211;definition tDCS (HD-tDCS) require special methodological considerations in the developing brain. Robotic TMS motor mapping may confer unique advantages for mapping, particularly in the developing brain. Here, we aim to provide a practical, standardized approach for two integrated methods capable of simultaneously exploring motor cortex modulation and motor maps in children. First, we describe a protocol for robotic TMS motor mapping. Individualized, MRI-navigated 12x12 grids centered on the motor cortex guide a robot to administer single-pulse TMS. Mean motor evoked potential (MEP) amplitudes per grid point are used to generate 3D motor maps of individual hand muscles with outcomes including map area, volume, and center of gravity. Tools to measure safety and tolerability of both methods are also included. Second, we describe the application of both tDCS and HD-tDCS to modulate the motor cortex and motor learning. An experimental training paradigm and sample results are described. These methods will advance the application of non-invasive brain stimulation in children.

We demonstrate protocols for the modulation (tDCS, HD-tDCS) and mapping (robotic TMS) of the motor cortex in children.

Modulación no invasiva y mapeo robótico de la corteza motora en el cerebro en desarrollo

Mapping the motor cortex with transcranial magnetic stimulation (TMS) has potential to interrogate motor cortex physiology and plasticity but carries ...

Neurociencias

Capturing Dynamic Finger Gesturing with High-resolution Surface Electromyography and Computer Vision

Finger gestures are a critical element in human communication, and as such, finger gesture recognition is widely studied as a human-computer interface for state-of-the-art prosthetics and optimized rehabilitation. Surface electromyography (sEMG), in conjunction with deep learning methods, is considered a promising method in this domain. However, current methods often rely on cumbersome recording setups and the identification of static hand positions, limiting their effectiveness in real-world applications. The protocol we report here presents an advanced approach combining a wearable surface EMG and finger&#160;tracking system to capture comprehensive data during dynamic hand movements. The method records muscle activity from soft printed electrode arrays (16 electrodes) placed on the forearm as subjects perform gestures in different hand positions and during movement. Visual instructions prompt subjects to perform specific gestures while EMG and finger positions are recorded. The integration of synchronized EMG recordings and finger tracking data enables comprehensive analysis of muscle activity patterns and corresponding gestures. The reported approach demonstrates the potential of combining EMG and visual tracking technologies as an important resource for developing intuitive and responsive gesture recognition systems with applications in prosthetics, rehabilitation, and interactive technologies. This protocol aims to guide researchers and practitioners, fostering further innovation and application of gesture recognition in dynamic and real-world scenarios.

The paper presents a comprehensive protocol for simultaneously recording hand-electromyography (EMG) and visual finger tracking during natural finger gesturing. The visual data is designed to serve as the ground truth for the development of accurate EMG-based computational models for finger gesture recognition.

Captura de gestos dinámicos con los dedos con electromiografía de superficie de alta resolución y visión artificial

Finger gestures are a critical element in human communication, and as such, finger gesture recognition is widely studied as a human-computer interface for ...