1,720,973 research outputs found
Performance Differences Using a Vibro-Tactile P300 BCI in LIS-Patients Diagnosed With Stroke and ALS
No full textPatients with locked-in syndrome (LIS) are typically unable to move or communicate and can be misdiagnosed as patients with disorders of consciousness (DOC). Behavioral assessment scales are limited in their ability to detect signs of consciousness in this population. Recent research has shown that brain-computer interface (BCI) technology could supplement behavioral scales and allows to establish communication with these severely disabled patients. In this study, we compared the vibro-tactile P300 based BCI performance in two groups of patients with LIS of different etiologies: stroke (n = 6) and amyotrophic lateral sclerosis (ALS) (n = 9). Two vibro-tactile paradigms were administered to the patients to assess conscious function and command following. The first paradigm is called vibrotactile evoked potentials (EPs) with two tactors (VT2), where two stimulators were placed on the patient's left and right wrist, respectively. The patients were asked to count the rare stimuli presented to one wrist to elicit a P300 complex to target stimuli only. In the second paradigm, namely vibrotactile EPs with three tactors (VT3), two stimulators were placed on the wrists as done in VT2, and one additional stimulator was placed on his/her back. The task was to count the rare stimuli presented to one wrist, to elicit the event-related potentials (ERPs). The VT3 paradigm could also be used for communication. For this purpose, the patient had to count the stimuli presented to the left hand to answer "yes" and to count the stimuli presented to the right hand to answer "no." All patients except one performed above chance level in at least one run in the VT2 paradigm. In the VT3 paradigm, all 6 stroke patients and 8/9 ALS patients showed at least one run above chance. Overall, patients achieved higher accuracies in VT2 than VT3. LIS patients due to ALS exhibited higher accuracies that LIS patients due to stroke, in both the VT2 and VT3 paradigms. These initial data suggest that controlling this type of BCI requires specific cognitive abilities that may be impaired in certain sub-groups of severely motor-impaired patients. Future studies on a larger cohort of patients are needed to better identify and understand the underlying cortical mechanisms of these differences
Effect of lower limb exoskeleton on the modulation of neural activity and gait classification
Full text link: Neurorehabilitation with robotic devices requires a paradigm shift to enhance human-robot interaction. The coupling of robot assisted gait training (RAGT) with a brain-machine interface (BMI) represents an important step in this direction but requires better elucidation of the effect of RAGT on the user's neural modulation. Here, we investigated how different exoskeleton walking modes modify brain and muscular activity during exoskeleton assisted gait. We recorded electroencephalographic (EEG) and electromyographic (EMG) activity from ten able-bodied volunteers walking with an exoskeleton with three modes of user assistance (i.e., transparent, adaptive and full assistance) and during free overground gait. Results identified that exoskeleton walking (irrespective of the exoskeleton mode) induces a stronger modulation of central mid-line mu (8-13 Hz) and low-beta (14-20 Hz) rhythms compared to free overground walking. These modifications are accompanied by a significant re-organization of the EMG patterns in exoskeleton walking. On the other hand, we observed no significant differences in neural activity during exoskeleton walking with the different assistance levels. We subsequently implemented four gait classifiers based on deep neural networks trained on the EEG data during the different walking conditions. Our hypothesis was that exoskeleton modes could impact the creation of a BMI-driven RAGT. We demonstrated that all classifiers achieved an average accuracy of 84.13 ± 3.49% in classifying swing and stance phases on their respective datasets. In addition, we demonstrated that the classifier trained on the transparent mode exoskeleton data can classify gait phases during adaptive and full modes with an accuracy of 78.3 ± 4.8%, while the classifier trained on free overground walking data fails to classify the gait during exoskeleton walking (accuracy of 59.4 ± 11.8%). These findings provide important insights into the effect of robotic training on neural activity and contribute to the advancement of BMI technology for improving robotic gait rehabilitation therapy
Brain computer interfaces for brain acquired damage
Full text linkEl terme Interfície Cervell-Ordinador (ICC), va sorgir als anys 70 pel Dr. Jacques J. Vidal, que mitjançant l’ús de l’electroencefalografia (EEG) fou el primer a intentar proporcionar una sortida alternativa als senyals cerebrals per controlar un dispositiu extern. L’objectiu principal d’aquesta fita era ajudar als pacients amb problemes de moviment i comunicació a relacionar-se amb el seu entorn.
Des de llavors, molts neurocientífics han emprat aquesta idea i han intentat posar-la en pràctica utilitzant diferents mètodes d’adquisició i processament del senyal, nous dispositius d’interacció, noves metes i objectius. Tot això ha facilitat l’aplicació d’aquesta tecnologia en moltes àrees, i actualment les ICC s’utilitzen per jugar a videojocs, moure cadires de rodes, facilitar l’escriptura en persones sense mobilitat, definir criteris i preferències en el món del comerç i el consum, o inclús poden servir com a detector de mentides.
Tot i així, el sector que presenta un major avenç en el desenvolupament de les ICC, és el sector biomèdic. A grans trets, podem utilitzar les ICC amb dues finalitats diferents dins de la neurorehabilitació; substituint una funció perduda o induint canvis en la plasticitat neuronal amb l’objectiu de restaurar o compensar la funció perduda.
Existeixen diferents principis per al registre dels senyals del cervell; de manera invasiva, col·locant els elèctrodes de registre dintre de la cavitat cranial, o de manera no invasiva, col·locant els elèctrodes de registre fora de la cavitat cranial. El mètode més conegut i difós és l’EEG. El seu ús és molt adequat en entorns clínics, té una resolució temporal molt precisa i és possible obtenir una retroalimentació en temps real que pot induir la plasticitat cortical i el restabliment de la funció motora normal.
En aquesta tesi presentem tres objectius diferents: (1) avaluar els afectes clínics de la rehabilitació mitjançant les ICC en pacients amb ictus, ja sigui realitzant un meta-anàlisi dels estudis publicats o avaluant els canvis funcionals dels pacients amb ictus després de la teràpia d’ICC; (2) explorar paràmetres alternatius per quantificar els efectes de les ICC en pacients amb ictus, avaluant diferents biomarcadors de l’EEG en pacients amb aquesta patologia i correlacionant aquests marcadors amb els resultats de les escales funcionals; (3) optimitzar el sistema ICC mitjançant la gamificació d’un avatar.El término Interfaz Cerebro-Computadora (ICC) surgió en los años 70 por el Dr. Jacques J. Vidal, que mediante el uso de la electroencefalografía (EEG) trató de dar una salida alternativa a las señales del cerebro para controlar un dispositivo externo. El objetivo principal de esta hazaña era ayudar a los pacientes con problemas de movimiento o comunicación a relacionarse con el entorno.
Desde entonces, muchos neurocientíficos han utilizado esta idea y han tratado de ponerla en práctica utilizando diferentes métodos de adquisición y procesamiento de señales, nuevos dispositivos de interacción y nuevas metas y objetivos. Todo ello ha facilitado la aplicación de esta tecnología en muchas áreas y actualmente las ICC se utilizan para jugar a videojuegos, mover sillas de ruedas, facilitar la escritura en personas sin movilidad, establecer criterios y preferencias de compra en el mundo del comercio y el consumo, o incluso pueden servir como detector de mentiras.
Sin embargo, el sector que presenta un mayor avance y desarrollo de las ICC es el sector biomédico. A grandes rasgos podemos utilizar las ICC con dos finalidades distintas dentro de la neurorehabilitación; sustituir una función perdida o inducir cambios en la plasticidad neuronal con el objetivo de restaurar o compensar dicha función perdida.
Hay diferentes principios para el registro de las señales del cerebro; de forma invasiva, colocando los electrodos de registro dentro de la cavidad craneal, o no invasiva, colocando los electrodos de registro fuera de la cavidad craneal. El método más conocido y difundido es la EEG. Su uso es adecuado para entornos clínicos, tiene una resolución temporal muy precisa y su retroalimentación en tiempo real puede inducir la plasticidad cortical y el restablecimiento de la función motora normal.
En esta tesis presentamos tres objetivos diferentes: (1) evaluar los efectos clínicos de la rehabilitación mediante las ICC en pacientes con ictus, ya sea realizando un meta-análisis de los estudios publicados o evaluando los cambios funcionales en los pacientes con ictus después de la terapia de ICC; (2) explorar parámetros alternativos para cuantificar los efectos de las ICC en pacientes con ictus, evaluando diferentes biomarcadores de electroencefalografía en pacientes con esta patología y correlacionando los posibles cambios en estos parámetros con los resultados en las escalas funcionales; (3) optimizar el sistema ICC utilizando mediante la gamificación de un avatar.The term Brain Computer Interface (BCI) emerged in the 70's by Dr. Jacques J Vidal, who by using electroencephalography (EEG) tried to give an alternative output to the brain signals in order to control an external device. The main objective of this feat was to help patients with impaired movement or communication to relate themselves to the environment.
Since then many neuroscientists have used this idea and have tried to implement it using different methods of signal acquisition and processing, new interaction devices, new goals and objectives. All this has facilitated the implementation of this technology in many areas and currently BCI is used to play video games, move wheelchairs, facilitate writing in people without mobility, establish criteria and purchase preferences in the world of marketing and consumption, or even serve as a lie detector.
However, the sector that presents the most marked progress and development of BCI is the biomedical sector. In rough outlines we can use BCI with two different purposes within the neurorehabilitation; to substitute a lost function or to induce neural plasticity changes with the aim to restore or compensate the lost function.
To restore a lost function by inducing neuroplastic changes in the brain is undoubtedly a challenging strategy but a feasible goal through BCI technology. This type of intervention requires that the patient invests time and effort in a therapy based on the practice of motor image and feedback mechanisms in real time.
There are different principles to record the brain signals; invasively, placing the recording electrodes inside the cranial cavity, or non-invasive, placing the recording electrodes outside of the cranial cavity. The best known and most widespread one is EEG, since they are suitable for clinical environments, have a highly accurate temporal resolution and their real-time feedback can induce cortical plasticity and the restoration of normal motor function.
On this thesis we present three different objectives: (1) to evaluate the clinical effects of rehabilitation based on BCI system in stroke patients, either by performing a meta-analysis of published studies or by evaluating functional changes in stroke patients after BCI training; (2) to explore alternative parameters to quantify effects of BCI in stroke patients, by evaluating different electroencephalography biomarkers in stroke patients and correlating potential changes in these parameters with functional scales; (3) to optimize the BCI system by using a new gamified avatar.Universitat Autònoma de Barcelona. Programa de Doctorat en Neurocièncie
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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