Littérature scientifique sur le sujet « Virtual reality, embodiment, rehabilitation, neuroplasticity »

The motor function impairment deriving from stroke injury has a negative impact on autonomy and on the activities of daily living. Several studies have demonstrated that learning new motor skills is important to induce neuroplasticity and functional recovery. To facilitate the activation of brain areas and consequently neuroplasticity, it may be advantageous to combine traditional motor rehabilitation with innovative technology, in order to promote motor re-learning and skill re-acquisition by means of an enhanced training. Following these principles, exercises should involve multiple sensory modalities exploiting the adaptive nature of the nervous system, in order to promote active patient participation. Movement re-learning could be improved by means of training in an enriched environment focused on optimizing the affordances between the motor system and the physical environment: virtual reality technologies allow for the possibility to create specific settings where the affordances are optimized. Several autors report that patients treated in virtual representation could, in both acute and chronic stroke, improve their arm motor function. Reinforced Feedback in a Virtual Environment (RFVE), can incorporate the elements necessary to maximize motor learning, such as repetitive and differentiated task practice, feedback of performance and results, and reinforcement of the motivation. The RFVE approach may lead to better rehabilitation outcomes in the treatment of the upper limb in stroke patients.

Virtual Reality (VR) technology is a relatively new application to rehabilitation medicine, yet it offers considerable potential to achieve significant successes in assessment, treatment and improved outcome, thereby increasing our knowledge of neuroplasticity. The capabilities of VR are especially evident in neurological rehabilitation, where cognitive and behavioural problems often interact with physical impairments to reduce the overall level of functioning and interaction. The need for effective interventions in neurological rehabilitation demands communication and collaboration between disciplines. This paper presents some of the current areas of the clinical applications of VR, emphasising the link between experimental evidence on recovery after brain damage and the clinical problems encountered in a ward setting.

Background. Stroke is a disease caused by the death of tissues in the brain. Clinical problems arise such as motor, sensory, cognitive, language, and emotional disorders. Motor disorders experienced by stroke patients are a decrease in functional ability. Virtual reality training is one of the physiotherapy exercises in handling stroke cases and is estimated to be able to modulate neuroplasticity so as to improve the functional capabilities of the extremities of stroke patients. Materials and Methods. This study is a literature review study with narrative methods. Purpose. Know how effective virtual reality exercises against improving the functional ability of the upper extremities in case of stroke. Result. The provision of virtual reality exercises is proven to improve the functional capabilities of the upper extremities in stroke patients. Virtual reality exercises for stroke provide audio and visual stimulation that triggers neuro-rehabilitation resulting in cortical re-mapping. And also provide motivation that triggers stroke patients to do exercises with a lot of reps so that neuroplasticity occurs. with various parameters such as Fugl-Meyer Upper Extremity Scale (FMA-UE), Wolf Motor Function Test (WMFT), and Box and Block Test (BBT). Conclusion. The administration of physiotherapy exercises using virtual reality can be an interventional solution to rehabilitate and improve the function of the upper extremities if paying attention to several things, such as virtual reality methods, dosages, and the availability of therapeutic tools. Keywords: Stroke, Virtual Reality training, Functional Abilities

In recent years, virtual reality (VR) has emerged as a new safe and effective tool for neurorehabilitation of different childhood and adulthood conditions. VR-based therapies can induce cortical reorganization and promote the activation of different neuronal connections over a wide range of ages, leading to contrasted improvements in motor and functional skills. The use of VR for the visual rehabilitation in amblyopia has been investigated in the last years, with the potential of using serious games combining perceptual learning and dichoptic stimulation. This combination of technologies allows the clinician to measure, treat, and control changes in interocular suppression, which is one of the factors leading to cortical alterations in amblyopia. Several clinical researches on this issue have been conducted, showing the potential of promoting visual acuity, contrast sensitivity, and stereopsis improvement. Indeed, several systems have been evaluated for amblyopia treatment including the use of different commercially available types of head mounted displays (HMDs). These HMDs are mostly well tolerated by patients during short exposures and do not cause significant long-term side effects, although their use has been occasionally associated with some visual discomfort and other complications in certain types of subjects. More studies are needed to confirm these promising therapies in controlled randomized clinical trials, with special emphasis on the definition of the most adequate planning for obtaining an effective recovery of the visual and binocular function.

Virtual reality (VR) is seen by some as a tool that may greatly improve, or even revolutionize cognitive rehabilitation. VR offers distinct advantages compared to classic rehabilitation using paper-and-pencil or computer-based training, such as immersion, the feeling of presence, embodiment of virtual players, ecological and multisensory stimulation. We here review recent clinical studies examining the effects of VR training in patients with stroke-induced cognitive deficits. Several trials reported evidence that VR training improves general cognition compared to standard cognitive training. However, the evidence remains controversial, as some of these studies had a high risk of bias. Regarding mood, there is some indication that immersive training improves depression scores in stroke patients, but the number of studies examining mood changes is very low. Finally, in the domain of spatial cognition the development of specific intervention techniques such as virtual prism adaptation provide avenues for clinical interventions, though well-controlled clinical trials are lacking. Together, the available evidence suggests that VR has the potential to improve rehabilitation particularly in domains requiring repetitive training in an immersed, ecological setting, or when a mismatch between body frames and the environment is created. Controlled clinical studies are required to examine the specific advantages of VR compared to classic interventions.

Background Embodiment through a virtual avatar is a key element for people to feel that they are in the virtual world. Objective This study aimed to elucidate the interaction between 2 methods of eliciting embodiment through a virtual avatar: motion synchronization and appearance similarity between a human and avatar, to understand embodiment (agency, body ownership, and self-location) and subjective experience (presence, simulator sickness, and emotion) in virtual reality. Methods Using a full-body motion capture system, 24 participants experienced their virtual avatars with a 3D-scanned face and size-matched body from a first-person perspective. This study used a 2 (motion; sync and async) × 2 (appearance; personalized and generic) within-subject design. Results The results indicated that agency and body ownership increased when motion and appearance were matched, whereas self-location, presence, and emotion were affected by motion only. Interestingly, if the avatar’s appearance was similar to the participants (personalized avatar), they formed an agency toward the avatar’s motion that was not performed by themselves. Conclusions Our findings would be applicable in the field of behavioral therapy, rehabilitation, and entertainment applications, by eliciting higher agency with a personalized avatar.

Among several perceptive traits of virtual reality, the relationship between the physical body and a self-avatar is unclear. In this study, we investigate a case of hyper-adaptability, i.e., the capability of users to adjust to the movements of an altered self-avatar when such movements abruptly and frequently change. Focusing on movements of the upper limbs, we show experimentally the effect of the frequency of variations in virtual body alterations on adaptability. Moreover, we report a positive evaluation of the sense of embodiment and the overall user experience with virtual reality, and finally underline how these studies can be considered a basis for the design and development of virtual rehabilitation systems.

Electroencephalography (EEG)-based brain–computer interfaces (BCIs) for motor rehabilitation aim to “close the loop” between attempted motor commands and sensory feedback by providing supplemental information when individuals successfully achieve specific brain patterns. Existing EEG-based BCIs use various displays to provide feedback, ranging from displays considered more immersive (e.g., head-mounted display virtual reality (HMD-VR)) to displays considered less immersive (e.g., computer screens). However, it is not clear whether more immersive displays improve neurofeedback performance and whether there are individual performance differences in HMD-VR versus screen-based neurofeedback. In this pilot study, we compared neurofeedback performance in HMD-VR versus a computer screen in 12 healthy individuals and examined whether individual differences on two measures (i.e., presence, embodiment) were related to neurofeedback performance in either environment. We found that, while participants’ performance on the BCI was similar between display conditions, the participants’ reported levels of embodiment were significantly different. Specifically, participants experienced higher levels of embodiment in HMD-VR compared to a computer screen. We further found that reported levels of embodiment positively correlated with neurofeedback performance only in HMD-VR. Overall, these preliminary results suggest that embodiment may relate to better performance on EEG-based BCIs and that HMD-VR may increase embodiment compared to computer screens.

Motor-learning literature focuses on simple laboratory-tasks due to their controlled manner and the ease to apply manipulations to induce learning and adaptation. Recently, we introduced a billiards paradigm and demonstrated the feasibility of real-world-neuroscience using wearables for naturalistic full-body motion-tracking and mobile-brain-imaging. Here we developed an embodied virtual-reality (VR) environment to our real-world billiards paradigm, which allows to control the visual feedback for this complex real-world task, while maintaining sense of embodiment. The setup was validated by comparing real-world ball trajectories with the trajectories of the virtual balls, calculated by the physics engine. We then ran our short-term motor learning protocol in the embodied VR. Subjects played billiard shots when they held the physical cue and hit a physical ball on the table while seeing it all in VR. We found comparable short-term motor learning trends in the embodied VR to those we previously reported in the physical real-world task. Embodied VR can be used for learning real-world tasks in a highly controlled environment which enables applying visual manipulations, common in laboratory-tasks and rehabilitation, to a real-world full-body task. Embodied VR enables to manipulate feedback and apply perturbations to isolate and assess interactions between specific motor-learning components, thus enabling addressing the current questions of motor-learning in real-world tasks. Such a setup can potentially be used for rehabilitation, where VR is gaining popularity but the transfer to the real-world is currently limited, presumably, due to the lack of embodiment.

The motor function impairment resulting from a stroke injury has a negative impact on autonomy, the activities of daily living thus the individuals affected by a stroke need long-term rehabilitation. Several studies have demonstrated that learning new motor skills is important to induce neuroplasticity and functional recovery. Innovative technologies used in rehabilitation allow one the possibility to enhance training throughout generated feedback. It seems advantageous to combine traditional motor rehabilitation with innovative technology in order to promote motor re-learning and skill re-acquisition by means of enhanced training. An environment enriched by feedback involves multiple sensory modalities and could promote active patient participation. Exercises in a virtual environment contain elements necessary to maximize motor learning, such as repetitive and diffe-rentiated task practice and feedback on the performance and results. The recovery of the limbs motor function in post-stroke subjects is one of the main therapeutic aims for patients and physiotherapist alike. Virtual reality as well as robotic devices allow one to provide specific treatment based on the reinforced feedback in a virtual environment (RFVE), artificially augmenting the sensory information coherent with the real-world objects and events. Motor training based on RFVE is emerging as an effective motor learning based techniques for the treatment of the extremities.

This thesis aim to test the effectiveness of an immersive virtual reality set-up by using an embodied virtual body in neurorehabilitation, specifically for motor and chronic pain disorders. More specifically, my first study entitled: Motor-cognitive training through Immersive Virtual Reality during the immobilization period in distal radius fracture patients, aims to investigate whether an upper limb immersive virtual reality (IVR) training program, may improve the motor and functional ability of a fractured arm in 54 distal radius fracture (DRF) patients during the immobilization period. With this intention, we compared 6 weeks of our IVR training group (n=20), with 6 weeks of a non-IVR training group (n=20), and with another conventional rehabilitation group (n=14), during the immobilization period. We observed that through our training program patients in the IVR training group reached a better motor-functional ability of the fractured arm after cast removal, compared to the patients in the control groups: non-immersive virtual reality group and conventional rehabilitation group. Finally, patients in the IVR training group presented better results in the follow-up (6 weeks later) compared to the control groups, especially in the wrist range of motion. Secondly, we wanted to investigate the effects of the upper limb IVR training program in chronic stroke patients without arm mobility with a case study: Using immersive virtual reality to rehabilitate the paretic upper limb in chronic stroke patients. In that case study, we tested the IVR program in three chronic stroke patients. To this aim all three chronic stroke patients, underwent two IVR training periods during 5 weeks every day, with a 3 weeks period of pause between the two training periods. After the first training period we found improvements in motor recovery of the paretic arm, as well as in the cognitive capability and quality of life of all three chronic stroke patients. Further, we observe that the motor-cognitive improvements obtained after the first IVR training period remained over time, during the period of pause. However, the second IVR training period was not effective to further enhance motor and cognitive improvements. Further, a pre-post brain imaging analysis by using resting state and diffusor tension imaging (DTI) techniques, allowed us to identify the underpinning neuroplastic changes following the first IVR training, that were mainly found at the cerebellum from a functional connectivity point of view, and in the primary motor cortex from an structural point of view, in all three chronic stroke patients. Finally, the last study of this thesis entitled: Immersive virtual reality reliefs pain in patients with complex regional pain syndrome type I but not with peripheral nerve injury, aimed to investigate whether varying properties of a virtual arm co-located with the real arm modulated pain ratings in patients with chronic arm/hand pain due to complex regional pain syndrome (CRPS) type I (without nerve injury) or peripheral nerve injury (PNI). CRPS (n=9) and PNI (n=10) patients were immersed in VR and the virtual arm was shown at four transparency levels (transparency test) and three sizes (size test). We evaluated pain ratings throughout the conditions and assessed the virtual experience, finding that patients with chronic pain can achieve levels of ownership and agency over a virtual arm similar to healthy participants. All seven conditions globally decreased pain ratings to half. Increasing transparency decreased pain in CRPS but did the opposite in PNI, while increasing size slightly increased pain ratings only in CRPS. In overall my doctoral thesis pave the way to the use of embodiment through an IVR set-up in neurorehabilitation following the principles of body illusions for rehabilitation.

This thesis aim to test the effectiveness of an immersive virtual reality set-up by using an embodied virtual body in neurorehabilitation, specifically for motor and chronic pain disorders. More specifically, my first study entitled: Motor-cognitive training through Immersive Virtual Reality during the immobilization period in distal radius fracture patients, aims to investigate whether an upper limb immersive virtual reality (IVR) training program, may improve the motor and functional ability of a fractured arm in 54 distal radius fracture (DRF) patients during the immobilization period. With this intention, we compared 6 weeks of our IVR training group (n=20), with 6 weeks of a non-IVR training group (n=20), and with another conventional rehabilitation group (n=14), during the immobilization period. We observed that through our training program patients in the IVR training group reached a better motor-functional ability of the fractured arm after cast removal, compared to the patients in the control groups: non-immersive virtual reality group and conventional rehabilitation group. Finally, patients in the IVR training group presented better results in the follow-up (6 weeks later) compared to the control groups, especially in the wrist range of motion. Secondly, we wanted to investigate the effects of the upper limb IVR training program in chronic stroke patients without arm mobility with a case study: Using immersive virtual reality to rehabilitate the paretic upper limb in chronic stroke patients. In that case study, we tested the IVR program in three chronic stroke patients. To this aim all three chronic stroke patients, underwent two IVR training periods during 5 weeks every day, with a 3 weeks period of pause between the two training periods. After the first training period we found improvements in motor recovery of the paretic arm, as well as in the cognitive capability and quality of life of all three chronic stroke patients. Further, we observe that the motor-cognitive improvements obtained after the first IVR training period remained over time, during the period of pause. However, the second IVR training period was not effective to further enhance motor and cognitive improvements. Further, a pre-post brain imaging analysis by using resting state and diffusor tension imaging (DTI) techniques, allowed us to identify the underpinning neuroplastic changes following the first IVR training, that were mainly found at the cerebellum from a functional connectivity point of view, and in the primary motor cortex from an structural point of view, in all three chronic stroke patients. Finally, the last study of this thesis entitled: Immersive virtual reality reliefs pain in patients with complex regional pain syndrome type I but not with peripheral nerve injury, aimed to investigate whether varying properties of a virtual arm co-located with the real arm modulated pain ratings in patients with chronic arm/hand pain due to complex regional pain syndrome (CRPS) type I (without nerve injury) or peripheral nerve injury (PNI). CRPS (n=9) and PNI (n=10) patients were immersed in VR and the virtual arm was shown at four transparency levels (transparency test) and three sizes (size test). We evaluated pain ratings throughout the conditions and assessed the virtual experience, finding that patients with chronic pain can achieve levels of ownership and agency over a virtual arm similar to healthy participants. All seven conditions globally decreased pain ratings to half. Increasing transparency decreased pain in CRPS but did the opposite in PNI, while increasing size slightly increased pain ratings only in CRPS. In overall my doctoral thesis pave the way to the use of embodiment through an IVR set-up in neurorehabilitation following the principles of body illusions for rehabilitation.
La presente tesis pretende hacer una breve revisión de las diferentes técnicas de integración multisensorial en rehabilitación utilizando principalmente el feedback visual y que han llevado a la implementación de la realidad virtual como herramienta terapéutica. Actualmente, la realidad virtual está adquiriendo un papel importante en el campo de la rehabilitación, y en específico en el campo de la neurorehabilitación para el tratamiento de alteraciones motoras, cognitivas y síndromes dolorosos. Sin embargo, todavía es una incógnita cuál es la manera más efectiva de aplicarla y que pacientes se pueden beneficiar en mayor grado de ella. Por esta razón, en esta tesis doctoral se presentan tres diferentes estudios en los cuales se aplica el uso de un sistema de realidad virtual immersiva, generando la ilusión de posesión de un cuerpo virtual. Específicamente, el primer estudio está realizado con pacientes ortopédicos. El segundo estudio es un caso estudio realizado con tres pacientes neurológicos, y el tercer estudio está realizado con un grupo de pacientes que sufren dolor crónico neuropático. En los tres estudios, se demuestra que el hecho de generar la ilusión de posesión de un cuerpo virtual mediante el uso de un sistema de realidad virtual immersiva, permite mejorar déficits motores, cognitivos y dolorosos en diferentes patologías. Esta tesis doctoral abre el camino a la introducción de nuevas técnicas de tratamiento en el campo de la neurorehablitación mediante el uso de técnicas de integración multisensorial, como los sistemas de realidad virtual immersiva.

Increasingly, virtual reality therapy (VRT) technologies are being used to augment pediatric rehabilitation. The mechanisms underlying success/failure of VRTs are not well understood. This thesis proposed an innovative 3-phase framework for evaluating VRT technologies with respect to neuroplasticity based on results of a scoping review of 21 studies. A case study was undertaken to demonstrate use of the framework to design and evaluate ‘Musical Steps’, a VRT technology aimed at promoting heel contact in toe-walking children. 5 therapists and 4 children were engaged in this study. The system accurately detected 88%(SD=7%) of heel contacts and was rated positively in usability testing (phase 1). Feasibility studies indicated that, while enjoyable, children did not understand the feedback provided and hence, heel contact was not increased (phase 2). These findings will direct future reiterations prior to evaluating clinical impact (phase 3). The proposed framework may enhance design and translation of therapeutically relevant VRTs.

Brain-computer interfaces (BCI) have been used to control the gait of a virtual self-avatar with the aim of being used in gait rehabilitation. A BCI decodes the brain signals representing a desire to do something and transforms them into a control command for controlling external devices. The feelings described by the participants when they control a self-avatar in an immersive virtual environment (VE) demonstrate that humans can be embodied in the surrogate body of an avatar (ownership illusion). It has recently been shown that inducing the ownership illusion and then manipulating the movements of one’s self-avatar can lead to compensatory motor control strategies. In order to maximize this effect, there is a need for a method that measures and monitors embodiment levels of participants immersed in virtual reality (VR) to induce and maintain a strong ownership illusion. This is particularly true given that reaching a high level of both BCI performance and embodiment are inter-connected. To reach one of them, the second must be reached as well. Some limitations of many existing systems hinder their adoption for neurorehabilitation: 1- some use motor imagery (MI) of movements other than gait; 2- most systems allow the user to take single steps or to walk but do not allow both, which prevents users from progressing from steps to gait; 3- most of them function in a single BCI mode (cue-paced or self-paced), which prevents users from progressing from machine-dependent to machine-independent walking. Overcoming the aforementioned limitations can be done by combining different control modes and options in one single system. However, this would have a negative impact on BCI performance, therefore diminishing its usefulness as a potential rehabilitation tool. In this case, there will be a need to enhance BCI performance. For such purpose, many techniques have been used in the literature, such as providing modified feedback (whereby the presented feedback is not consistent with the user’s MI), sequential training (recalibrating the classifier as more data becomes available). This thesis was developed over 3 studies. The objective in study 1 was to investigate the possibility of measuring the level of embodiment of an immersive self-avatar, during the performing, observing and imagining of gait, using electroencephalogram (EEG) techniques, by presenting visual feedback that conflicts with the desired movement of embodied participants. The objective of study 2 was to develop and validate a BCI to control single steps and forward walking of an immersive virtual reality (VR) self-avatar, using mental imagery of these actions, in cue-paced and self-paced modes. Different performance enhancement strategies were implemented to increase BCI performance. The data of these two studies were then used in study 3 to construct a generic classifier that could eliminate offline calibration for future users and shorten training time. Twenty different healthy participants took part in studies 1 and 2. In study 1, participants wore an EEG cap and motion capture markers, with an avatar displayed in a head-mounted display (HMD) from a first-person perspective (1PP). They were cued to either perform, watch or imagine a single step forward or to initiate walking on a treadmill. For some of the trials, the avatar took a step with the contralateral limb or stopped walking before the participant stopped (modified feedback). In study 2, participants completed a 4-day sequential training to control the gait of an avatar in both BCI modes. In cue-paced mode, they were cued to imagine a single step forward, using their right or left foot, or to walk forward. In the self-paced mode, they were instructed to reach a target using the MI of multiple steps (switch control mode) or maintaining the MI of forward walking (continuous control mode). The avatar moved as a response to two calibrated regularized linear discriminant analysis (RLDA) classifiers that used the μ power spectral density (PSD) over the foot area of the motor cortex as features. The classifiers were retrained after every session. During the training, and for some of the trials, positive modified feedback was presented to half of the participants, where the avatar moved correctly regardless of the participant’s real performance. In both studies, the participants’ subjective experience was analyzed using a questionnaire. Results of study 1 show that subjective levels of embodiment correlate strongly with the power differences of the event-related synchronization (ERS) within the μ frequency band, and over the motor and pre-motor cortices between the modified and regular feedback trials. Results of study 2 show that all participants were able to operate the cued-paced BCI and the selfpaced BCI in both modes. For the cue-paced BCI, the average offline performance (classification rate) on day 1 was 67±6.1% and 86±6.1% on day 3, showing that the recalibration of the classifiers enhanced the offline performance of the BCI (p < 0.01). The average online performance was 85.9±8.4% for the modified feedback group (77-97%) versus 75% for the non-modified feedback group. For self-paced BCI, the average performance was 83% at switch control and 92% at continuous control mode, with a maximum of 12 seconds of control. Modified feedback enhanced BCI performances (p =0.001). Finally, results of study 3 show that the constructed generic models performed as well as models obtained from participant-specific offline data. The results show that there it is possible to design a participant-independent zero-training BCI.
Les interfaces cerveau-ordinateur (ICO) ont été utilisées pour contrôler la marche d'un égo-avatar virtuel dans le but d'être utilisées dans la réadaptation de la marche. Une ICO décode les signaux du cerveau représentant un désir de faire produire un mouvement et les transforme en une commande de contrôle pour contrôler des appareils externes. Les sentiments décrits par les participants lorsqu'ils contrôlent un égo-avatar dans un environnement virtuel immersif démontrent que les humains peuvent être incarnés dans un corps d'un avatar (illusion de propriété). Il a été récemment démontré que provoquer l’illusion de propriété puis manipuler les mouvements de l’égo-avatar peut conduire à des stratégies de contrôle moteur compensatoire. Afin de maximiser cet effet, il existe un besoin d'une méthode qui mesure et surveille les niveaux d’incarnation des participants immergés dans la réalité virtuelle (RV) pour induire et maintenir une forte illusion de propriété. D'autre part, atteindre un niveau élevé de performances (taux de classification) ICO et d’incarnation est interconnecté. Pour atteindre l'un d'eux, le second doit également être atteint. Certaines limitations de plusieurs de ces systèmes entravent leur adoption pour la neuroréhabilitation: 1- certains utilisent l'imagerie motrice (IM) des mouvements autres que la marche; 2- la plupart des systèmes permettent à l'utilisateur de faire des pas simples ou de marcher mais pas les deux, ce qui ne permet pas à un utilisateur de passer des pas à la marche; 3- la plupart fonctionnent en un seul mode d’ICO, rythmé (cue-paced) ou auto-rythmé (self-paced). Surmonter les limitations susmentionnées peut être fait en combinant différents modes et options de commande dans un seul système. Cependant, cela aurait un impact négatif sur les performances de l’ICO, diminuant ainsi son utilité en tant qu'outil potentiel de réhabilitation. Dans ce cas, il sera nécessaire d'améliorer les performances des ICO. À cette fin, de nombreuses techniques ont été utilisées dans la littérature, telles que la rétroaction modifiée, le recalibrage du classificateur et l'utilisation d'un classificateur générique. Le projet de cette thèse a été réalisé en 3 études, avec objectif d'étudier dans l'étude 1, la possibilité de mesurer le niveau d'incarnation d'un égo-avatar immersif, lors de l'exécution, de l'observation et de l'imagination de la marche, à l'aide des techniques encéphalogramme (EEG), en présentant une rétroaction visuelle qui entre en conflit avec la commande du contrôle moteur des sujets incarnés. L'objectif de l'étude 2 était de développer un BCI pour contrôler les pas et la marche vers l’avant d'un égo-avatar dans la réalité virtuelle immersive, en utilisant l'imagerie motrice de ces actions, dans des modes rythmés et auto-rythmés. Différentes stratégies d'amélioration des performances ont été mises en œuvre pour augmenter la performance (taux de classification) de l’ICO. Les données de ces deux études ont ensuite été utilisées dans l'étude 3 pour construire des classificateurs génériques qui pourraient éliminer la calibration hors ligne pour les futurs utilisateurs et raccourcir le temps de formation. Vingt participants sains différents ont participé aux études 1 et 2. Dans l'étude 1, les participants portaient un casque EEG et des marqueurs de capture de mouvement, avec un avatar affiché dans un casque de RV du point de vue de la première personne (1PP). Ils ont été invités à performer, à regarder ou à imaginer un seul pas en avant ou la marche vers l’avant (pour quelques secondes) sur le tapis roulant. Pour certains essais, l'avatar a fait un pas avec le membre controlatéral ou a arrêté de marcher avant que le participant ne s'arrête (rétroaction modifiée). Dans l'étude 2, les participants ont participé à un entrainement séquentiel de 4 jours pour contrôler la marche d'un avatar dans les deux modes de l’ICO. En mode rythmé, ils ont imaginé un seul pas en avant, en utilisant leur pied droit ou gauche, ou la marche vers l’avant . En mode auto-rythmé, il leur a été demandé d'atteindre une cible en utilisant l'imagerie motrice (IM) de plusieurs pas (mode de contrôle intermittent) ou en maintenir l'IM de marche vers l’avant (mode de contrôle continu). L'avatar s'est déplacé en réponse à deux classificateurs ‘Regularized Linear Discriminant Analysis’ (RLDA) calibrés qui utilisaient comme caractéristiques la densité spectrale de puissance (Power Spectral Density; PSD) des bandes de fréquences µ (8-12 Hz) sur la zone du pied du cortex moteur. Les classificateurs ont été recalibrés après chaque session. Au cours de l’entrainement et pour certains des essais, une rétroaction modifiée positive a été présentée à la moitié des participants, où l'avatar s'est déplacé correctement quelle que soit la performance réelle du participant. Dans les deux études, l'expérience subjective des participants a été analysée à l'aide d'un questionnaire. Les résultats de l'étude 1 montrent que les niveaux subjectifs d’incarnation sont fortement corrélés à la différence de la puissance de la synchronisation liée à l’événement (Event-Related Synchronization; ERS) sur la bande de fréquence μ et sur le cortex moteur et prémoteur entre les essais de rétroaction modifiés et réguliers. L'étude 2 a montré que tous les participants étaient capables d’utiliser le BCI rythmé et auto-rythmé dans les deux modes. Pour le BCI rythmé, la performance hors ligne moyenne au jour 1 était de 67±6,1% et 86±6,1% au jour 3, ce qui montre que le recalibrage des classificateurs a amélioré la performance hors ligne du BCI (p <0,01). La performance en ligne moyenne était de 85,9±8,4% pour le groupe de rétroaction modifié (77-97%) contre 75% pour le groupe de rétroaction non modifié. Pour le BCI auto-rythmé, la performance moyenne était de 83% en commande de commutateur et de 92% en mode de commande continue, avec un maximum de 12 secondes de commande. Les performances de l’ICO ont été améliorées par la rétroaction modifiée (p = 0,001). Enfin, les résultats de l'étude 3 montrent que pour la classification des initialisations des pas et de la marche, il a été possible de construire des modèles génériques à partir de données hors ligne spécifiques aux participants. Les résultats montrent la possibilité de concevoir une ICO ne nécessitant aucun entraînement spécifique au participant.

Stroke is one of the main causes of disability in Western countries. Damaged brain areas are not able to provide the fine-tuned muscular control typical of human upper-limbs, resulting in many symptoms that affect consistently patients' daily-life activities. Neurological rehabilitation is a multifactorial process that aims at partially restoring the functional properties of the impaired limbs, taking advantage of neuroplasticity, i.e. the capability of re-aggregating neural networks in order to repair and substitute the damaged neural circuits. Recently, many virtual reality-based, robotic and exoskeleton approaches have been developed to exploit neuroplasticity and help conventional therapies in clinic. The effectiveness of such methods is only partly demonstrated. Patients' performances and clinical courses are assessed via a variety of complex and expensive sensors and time-consuming techniques: motion capture systems, EMG, EEG, MRI, interaction forces with the devices, clinical scales. Evidences show that benefits are proportional to treatment duration and intensity. Clinics can provide intensive assistance just for a limited amount of time. Thus, in order to preserve the benefits and increase them in time, the rehabilitative process should be continued at home. Simplicity, easiness of use, affordability, reliability and capability of storing logs of the rehabilitative sessions are the most important requirements in developing devices to allow and facilitate domestic rehabilitation. Tracking systems are the primary sources of information to assess patients' motor performances. While expensive and sophisticated techniques can investigate neuroplasticity, neural activation (fMRI) and muscle stimulation patterns (EMG), the kinematic assessment is fundamental to provide basic but essential quantitative evaluations as range of motion, motor control quality and measurements of motion abilities. Microsoft Kinect and Kinect One are programmable and affordable tracking sensors enabling the measurement of the positions of human articular centers. They are widely used in rehabilitation, mainly for interacting with virtual environments and videogames, or training motor primitives and single joints. In this paper, the authors propose a novel use of the Kinect and Kinect One sensors in a medical protocol specifically developed to assess the motor control quality of neurologically impaired people. It is based on the evaluation of clinically meaningful synthetic performance indexes, derived from previously developed experiences in upper-limb robotic treatments. The protocol provides evaluations taking into account kinematics (articular clinical angles, velocities, accelerations), dynamics (shoulder torque and shoulder effort index), motor and postural control quantities (normalized jerk of the wrist, coefficient of periodicity, center of mass displacement). The Kinect-based platform performance evaluation was off-line compared with the measurements obtained with a marker-based motion tracking system during the execution of reaching tasks against gravity. Preliminary results based on the Kinect sensor suggest its efficacy in clustering healthy subjects and patients according to their motor performances, despite the less sensibility in respect to the marker-based system used for comparison. A software library to evaluate motor performances has been developed by the authors, implemented in different programming languages and is available for on-line use during training/evaluation sessions (Figure 1). The Kinect sensor coupled with the developed computational library is proposed as an assessment technology during domestic rehabilitation therapies with on-line feedback, enabled by an application featuring tracking, graphical representation and data logging. An experimental campaign is under development on post-stroke patients with the Kinect-One sensor. Preliminary results on patients with different residual functioning and level of impairment indicate the capability of the whole system in discriminating motor performances.

Stroke is one of the main causes of disability in Western countries. Damaged brain areas are not able to provide the fine-tuned muscular control typical of human upper-limbs, resulting in many symptoms that affect consistently patients' daily-life activities. Neurological rehabilitation is a multifactorial process that aims at partially restoring the functional properties of the impaired limbs, taking advantage of neuroplasticity, i.e. the capability of re-aggregating neural networks in order to repair and substitute the damaged neural circuits. Recently, many virtual reality-based, robotic and exoskeleton approaches have been developed to exploit neuroplasticity and help conventional therapies in clinic. The effectiveness of such methods is only partly demonstrated. Patients' performances and clinical courses are assessed via a variety of complex and expensive sensors and time-consuming techniques: motion capture systems, EMG, EEG, MRI, interaction forces with the devices, clinical scales. Evidences show that benefits are proportional to treatment duration and intensity. Clinics can provide intensive assistance just for a limited amount of time. Thus, in order to preserve the benefits and increase them in time, the rehabilitative process should be continued at home. Simplicity, easiness of use, affordability, reliability and capability of storing logs of the rehabilitative sessions are the most important requirements in developing devices to allow and facilitate domestic rehabilitation. Tracking systems are the primary sources of information to assess patients' motor performances. While expensive and sophisticated techniques can investigate neuroplasticity, neural activation (fMRI) and muscle stimulation patterns (EMG), the kinematic assessment is fundamental to provide basic but essential quantitative evaluations as range of motion, motor control quality and measurements of motion abilities. Microsoft Kinect and Kinect One are programmable and affordable tracking sensors enabling the measurement of the positions of human articular centers. They are widely used in rehabilitation, mainly for interacting with virtual environments and videogames, or training motor primitives and single joints. In this paper, the authors propose a novel use of the Kinect and Kinect One sensors in a medical protocol specifically developed to assess the motor control quality of neurologically impaired people. It is based on the evaluation of clinically meaningful synthetic performance indexes, derived from previously developed experiences in upper-limb robotic treatments. The protocol provides evaluations taking into account kinematics (articular clinical angles, velocities, accelerations), dynamics (shoulder torque and shoulder effort index), motor and postural control quantities (normalized jerk of the wrist, coefficient of periodicity, center of mass displacement). The Kinect-based platform performance evaluation was off-line compared with the measurements obtained with a marker-based motion tracking system during the execution of reaching tasks against gravity. Preliminary results based on the Kinect sensor suggest its efficacy in clustering healthy subjects and patients according to their motor performances, despite the less sensibility in respect to the marker-based system used for comparison. A software library to evaluate motor performances has been developed by the authors, implemented in different programming languages and is available for on-line use during training/evaluation sessions (Figure 1). The Kinect sensor coupled with the developed computational library is proposed as an assessment technology during domestic rehabilitation therapies with on-line feedback, enabled by an application featuring tracking, graphical representation and data logging. An experimental campaign is under development on post-stroke patients with the Kinect-One sensor. Preliminary results on patients with different residual functioning and level of impairment indicate the capability of the whole system in discriminating motor performances.

Spinocerebellar Ataxia (SCA) is an autosomal dominant disease with progressive decline towards functional capacity. Although studies had shown that there are various SCA types, physical medicine and rehabilitation approach would focus mostly on functional aspects in each individuals. Analysis through International Classification of Functioning, Disability, and Health would assist clinicians to identify activity and participation aspects of SCA, mostly revolves around mobility function. Good correlation of mobility with quality of life was also reported, and thus it is only natural that this becomes the main focus of rehabilitative intervention. Approximately one hour physical exercise session focusing on postural control and balance was proven to be effective in improving disease related measurement tool, functional capacity, and quality of life. These benefits could be improved through newer therapies such as exercise games and virtual reality, virtually creates a rapidly changing environment, thus providing training through anticipatory actions. It is speculated that neuroplasticity through self-recognition of errors are the main physiology of recovery in SCA. Finally, it could be seen that rehabilitation intervention remains to be a cornerstone in current ataxia therapy, with goals of achieving exercise gains while alleviating the natural functional decline of the disease.

Introduction: the use of virtual reality in Parkinson’s disease is a very effective therapy, as it promotes important actions for the knowledge of the motor, stimulating neuroplasticity, through visual feedback. Study design: This is a systematic review of the literature. Objective: The objective of this study was to analyze the use of reality in the rehabilitation of functional capacity in the different stages of Parkinson’s disease. Methods: this is a systematic review, carried out from January to August 2017, by means of electronic search in the databases: Pubmed, Scielo, Lilacs, Science Direct and Medline. The descriptors used were: virtual, video game, Parkinson’s, physiotherapy and rehabilitation and all the words in English. They were defined as inclusion criteria for studies that used virtual reality as treatment for patients with Parkinson’s, classifying patients in stages (I, II, III, IV and V) according to the Hoehn & Yahr scale. Literature review articles, description of virtual reality without showing the sample of statistical results and case study were excluded. Results: 7 articles were selected. After analyzing them, it was possible to observe that patients in the early stages showed improvement in perception, gait and balance. However, patients who were in other more advanced stages of the disease only improved their perception. Conclusion: patients in the early stages of clinical Parkinson’s disease have satisfactory results when compared to the advanced stages.