Transcranial Direct Current Stimulatio (tDCS) and Transcranial Current Alterning Stimulation (tACS) Review

[Abstract] This literature review is aimed to explore the main technical characteristics of both transcranial direct current stimulation (tDCS) and transcranial alternate current stimulation (tACS) using the latest research on both healthy and impaired subjects. These techniques have no official standards developed yet. Our intent is to underline the main properties and problems linked with the application of those techniques which show diverse, and sometimes even opposite, results depending mainly on electrode positioning and underlying brain activity.This research has been carried out in the framework of the project Associate - Decoding and stimulation of motor and sensory brain activity to support long term potentiation through Hebbian and paired associative stimulation during rehabilitation of gait (DPI2014-58431-C4-2-R), funded by the Spanish Ministry of Economy and Competitiveness and by the European Union through the European Regional Development Fund (ERDF) A way to build Europehttps://doi.org/10.17979/spudc.978849749808

Low cost 3D-printed hand exoskeleton controlled by a BCI

[Abstract] The aim of this work was to build and design a low-cost active hand exoskeleton to be used in rehabilitation of post-stroke patients. The hand exoskeleton was 3D printer and it allowed an active flexion and extension of the fingers. The exoskeleton designed was powered by three servomotors which pulled tendons to shorten the distance over or under the joints. This produced a natural hand movement close to a biological one. The exoskeleton was controlled by a Brain-Machine interface (BMI) utilizing an EEG-cap for measuring the brain activity. This way, two subjects tested the whole system opening and closing the hand exoskeleton by using only their thoughts.[Resumen] El objetivo de este trabajo fue construir y diseñar un exoesqueleto de mano activa de bajo costo para ser utilizado en la rehabilitación de pacientes post-accidente cerebro vascular. El exoesqueleto de mano era una impresora 3D que permitía una flexión activa y extensión de los dedos. El exoesqueleto diseñado fue impulsado por tres servomotores que tiraban de los tendones para acortar la distancia sobre o debajo de las articulaciones. Esto produjo un movimiento natural de la mano cerca de uno biológico. El exoesqueleto fue controlado por una interfaz Brain-Machine (BMI) que utiliza una tapa EEG para medir la actividad cerebral. De esta manera, dos sujetos probaron todo el sistema abriendo y cerrando el exoesqueleto de la mano usando solo sus pensamientos

Improving Real-Time Lower Limb Motor Imagery Detection Using tDCS and an Exoskeleton

The aim of this work was to test if a novel transcranial direct current stimulation (tDCS) montage boosts the accuracy of lower limb motor imagery (MI) detection by using a real-time brain-machine interface (BMI) based on electroencephalographic (EEG) signals. The tDCS montage designed was composed of two anodes and one cathode: one anode over the right cerebrocerebellum, the other over the motor cortex in Cz, and the cathode over FC2 (using the International 10–10 system). The BMI was designed to detect two MI states: relax and gait MI; and was based on finding the power at the frequency which attained the maximum power difference between the two mental states at each selected EEG electrode. Two different single-blind experiments were conducted, E1 and a pilot test E2. E1 was based on visual cues and feedback and E2 was based on auditory cues and a lower limb exoskeleton as feedback. Twelve subjects participated in E1, while four did so in E2. For both experiments, subjects were separated into two equally-sized groups: sham and active tDCS. The active tDCS group achieved 12.6 and 8.2% higher detection accuracy than the sham group in E1 and E2, respectively, reaching 65 and 81.6% mean detection accuracy in each experiment. The limited results suggest that the exoskeleton (E2) enhanced the detection of the MI tasks with respect to the visual feedback (E1), increasing the accuracy obtained in 16.7 and 21.2% for the active tDCS and sham groups, respectively. Thus, the small pilot study E2 indicates that using an exoskeleton in real-time has the potential of improving the rehabilitation process of cerebrovascular accident (CVA) patients, but larger studies are needed in order to further confirm this claim

Evaluación de artefactos en un Sistem BMI para la medición de niveles de atención durante movimiento con exoesqueleto de miembro inferior

[Resumen] Con la creciente preocupación social ante el número de personas que sufren de disfunciones motoras, surgen múltiples estudios orientados a la mejora de las terapias de rehabilitación. En este aspecto, ha surgido una rama científica centrada en el desarrollo de interfaces cerebro-máquina que controlan el movimiento de un exoesqueleto durante terapias de rehabilitación. En este trabajo se presenta una interfaz cerebro-máquina capaz de proporcionar a un exoesqueleto el nivel de atención que un paciente presenta durante la marcha. Para evaluar la validez de los resultados de este sistema, se realizan pruebas empleando y no empleando un exoesqueleto. Los resultados muestran una caída considerable en el los aciertos cuando se utiliza el exoesqueleto debido a la aparición de artefactos de movimiento

Comparativa de algoritmos para la detección online de imaginación motora de la marcha basado en señales de EEG

[Resumen] Las interfaces cerebro-máaquina son cada vez más usadas para mejorar el proceso de rehabilitación de personas que han sufrido un accidente cerebrovas- cular. En este trabajo se comparan dos algoritmos para determinar cual de ellos ofrece mayor preci- sión de manera online dos tareas mentales: imagi- nación de marcha y relajación. Ambos algoritmos detectan los cambios en la potencia a través de la desincronización y sincronización de eventos rela- cionados. El algoritmo 1 está basado en la media de las bandas de frecuencia 8-13 Hz y 20-35 Hz por cada electrodo. El algoritmo 2 se fundamenta en la potencia a la frecuencia de máxima varia- bilidad entre las dos tareas en cada electrodo. Los resultados indican que el algoritmo 2 ofrece mayor precisión que el algoritmo 1 en 4 de 5 usuarios.Ministerio de Economía y Competitividad; DPI2014-58431-C4-2-

Application of the Stockwell Transform to Electroencephalographic Signal Analysis during Gait Cycle

The analysis of electroencephalographic signals in frequency is usually not performed by transforms that can extract the instantaneous characteristics of the signal. However, the non-steady state nature of these low voltage electrical signals makes them suitable for this kind of analysis. In this paper a novel tool based on Stockwell transform is tested, and compared with techniques such as Hilbert-Huang transform and Fast Fourier Transform, for several healthy individuals and patients that suffer from lower limb disability. Methods are compared with the Weighted Discriminator, a recently developed comparison index. The tool developed can improve the rehabilitation process associated with lower limb exoskeletons with the help of a Brain-Machine Interface

Exoesqueleto de mano impreso en 3D de bajo costo controlado por un BCI

Comunicación presentada a las XXXIX Jornadas de Automática, celebradas en Badajoz del 5 al 7 de Septiembre de 2018 y organizada por la Universidad de ExtremaduraThe aim of this work was to build and design a low-cost active hand exoskeleton to be used in rehabilitation of post-stroke patients. The hand exoskeleton was 3D printer and it allowed an active flexion and extension of the fingers. The exoskeleton designed was powered by three servomotors which pulled tendons to shorten the distance over or under the joints. This produced a natural hand movement close to a biological one. The exoskeleton was controlled by a Brain-Machine interface (BMI) utilizing an EEG-cap for measuring the brain activity. This way, two subjects tested the whole system opening and closing the hand exoskeleton by using only their thoughts.El objetivo de este trabajo fue construir y diseñar un exoesqueleto de mano activa de bajo costo para ser utilizado en la rehabilitación de pacientes post-accidente cerebro vascular. El exoesqueleto de mano era una impresora 3D que permitía una flexión activa y extensión de los dedos. El exoesqueleto diseñado fue impulsado por tres servomotores que tiraban de los tendones para acortar la distancia sobre o debajo de las articulaciones. Esto produjo un movimiento natural de la mano cerca de uno biológico. El exoesqueleto fue controlado por una interfaz Brain-Machine (BMI) que utiliza una tapa EEG para medir la actividad cerebral. De esta manera, dos sujetos probaron todo el sistema abriendo y cerrando el exoesqueleto de la mano usando solo sus pensamientos.peerReviewe

A preliminary study of the evaluation of artistic creativity based on the analysis of electroencephalographic signals

[Resumen] Para evaluar la creatividad es habitual el uso de tests de creatividad, tales como el test de pensamiento creativo de Torrance. Su empleo está extendido en el ámbito de la educación e incluso en el mundo empresarial. No obstante, por la propia naturaleza de estas pruebas resulta necesaria la supervisión por parte de diversos expertos de las tareas realizadas, no dejando de tener esta evaluación una parte subjetiva. Mediante nuestra investigación, pretendemos plantear las bases para poder evaluar de forma alternativa la creatividad de un sujeto, en base a la evaluación de las señales electroencefalografías durante un proceso de pensamiento y acción creativa. Este artículo muestra los procedimientos a llevar a cabo durante los tests de creatividad y el tratamiento de la señal eléctrica a realizar tras los mismos. Todo ello, con el fin de definir en futuras investigaciones un índice objetivo de creatividad.[Abstract] Creativity is usually evaluated by creativity tests, such as Torrance creativity thinking test. This test is extended in education and companies. However, because of the characteristics of the test, it is necessary the participation and supervision of experts in the evaluation of the performed tasks, adding a subjective point to the qualification. Our research tries to set up the basis to an alternative evaluation of creativity, based on the analysis of the electroencephalographic signals of a subject during a process of creativity thinking and action. The article shows the protocols proposed and the selected signal processing algorithms applied to the electroencephalographic signals acquired. All of this, with the future intention of obtaining an objective index of creativity

Exoesqueleto de mano impreso en 3D de bajo costo controlado por un BCI

Comunicación presentada a las XXXIX Jornadas de Automática, celebradas en Badajoz del 5 al 7 de Septiembre de 2018 y organizada por la Universidad de ExtremaduraThe aim of this work was to build and design a low-cost active hand exoskeleton to be used in rehabilitation of post-stroke patients. The hand exoskeleton was 3D printer and it allowed an active flexion and extension of the fingers. The exoskeleton designed was powered by three servomotors which pulled tendons to shorten the distance over or under the joints. This produced a natural hand movement close to a biological one. The exoskeleton was controlled by a Brain-Machine interface (BMI) utilizing an EEG-cap for measuring the brain activity. This way, two subjects tested the whole system opening and closing the hand exoskeleton by using only their thoughts.El objetivo de este trabajo fue construir y diseñar un exoesqueleto de mano activa de bajo costo para ser utilizado en la rehabilitación de pacientes post-accidente cerebro vascular. El exoesqueleto de mano era una impresora 3D que permitía una flexión activa y extensión de los dedos. El exoesqueleto diseñado fue impulsado por tres servomotores que tiraban de los tendones para acortar la distancia sobre o debajo de las articulaciones. Esto produjo un movimiento natural de la mano cerca de uno biológico. El exoesqueleto fue controlado por una interfaz Brain-Machine (BMI) que utiliza una tapa EEG para medir la actividad cerebral. De esta manera, dos sujetos probaron todo el sistema abriendo y cerrando el exoesqueleto de la mano usando solo sus pensamientos.peerReviewe

Personalized Offline and Pseudo-Online BCI Models to Detect Pedaling Intent

The aim of this work was to design a personalized BCI model to detect pedaling intention through EEG signals. The approach sought to select the best among many possible BCI models for each subject. The choice was between different processing windows, feature extraction algorithms and electrode configurations. Moreover, data was analyzed offline and pseudo-online (in a way suitable for real-time applications), with a preference for the latter case. A process for selecting the best BCI model was described in detail. Results for the pseudo-online processing with the best BCI model of each subject were on average 76.7% of true positive rate, 4.94 false positives per minute and 55.1% of accuracy. The personalized BCI model approach was also found to be significantly advantageous when compared to the typical approach of using a fixed feature extraction algorithm and electrode configuration. The resulting approach could be used to more robustly interface with lower limb exoskeletons in the context of the rehabilitation of stroke patients