A virtual reality-based system integrated with fmri to study neural mechanisms of action observation-execution: a proof of concept study

Neural correlates of bradykinesia in Parkinson's disease: a kinematic and functional MRI study

Bradykinesia is defined as a "complex" of motor alterations including decreased movement amplitude and/or speed and tendency to reduce them with movement repetition (sequence effect). This study aimed at investigating the neural and kinematic correlates of bradykinesia during hand-tapping in people with Parkinson's disease (pwPD) relative to healthy controls. Twenty-five pwPD and 25 age- and sex-matched healthy controls underwent brain functional MRI (fMRI) during a hand-tapping task: subjects alternatively opened and closed their right hand as fully and quickly as possible. Hand-tapping kinematic parameters were objectively measured during the fMRI task using an optical fibre glove. During the fMRI task, pwPD showed reduced hand-tapping amplitude (hypokinesia) and a greater sequence effect. PwPD relative to healthy controls showed a reduced activity of fronto-parietal areas, middle cingulum/supplementary motor area (SMA), parahippocampus, pallidum/thalamus and motor cerebellar areas. Moreover, pwPD showed an increased activity of brain cognitive areas such as superior temporal gyrus, posterior cingulum, and cerebellum crus I. The decreased activity of cerebellum IV-V-VI, vermis IV-V, inferior frontal gyrus, and cingulum/SMA correlated with hypokinesia and with the sequence effect. Interestingly, a reduced activity of areas involved in motor planning and timing correlated both with hypokinesia and with the sequence effect in pwPD. This study has the major strength of collecting objective motor parameters and brain activity simultaneously, providing a unique opportunity to investigate the neural correlates of the "bradykinesia complex".

Brain Signatures of Embodied Semantics and Language: A Consensus Paper

According to embodied theories (including embodied, embedded, extended, enacted, situated, and grounded approaches to cognition), language representation is intrinsically linked to our interactions with the world around us, which is reflected in specific brain signatures during language processing and learning. Moving on from the original rivalry of embodied vs. amodal theories, this consensus paper addresses a series of carefully selected questions that aim at determining when and how rather than whether motor and perceptual processes are involved in language processes. We cover a wide range of research areas, from the neurophysiological signatures of embodied semantics, e.g., event-related potentials and fields as well as neural oscillations, to semantic processing and semantic priming effects on concrete and abstract words, to first and second language learning and, finally, the use of virtual reality for examining embodied semantics. Our common aim is to better understand the role of motor and perceptual processes in language representation as indexed by language comprehension and learning. We come to the consensus that, based on seminal research conducted in the field, future directions now call for enhancing the external validity of findings by acknowledging the multimodality, multidimensionality, flexibility and idiosyncrasy of embodied and situated language and semantic processes.

Technologies in Home-Based Digital Rehabilitation: Scoping Review

BACKGROUND

Due to growing pressure on the health care system, a shift in rehabilitation to home settings is essential. However, efficient support for home-based rehabilitation is lacking. The COVID-19 pandemic has further exacerbated these challenges and has affected individuals and health care professionals during rehabilitation. Digital rehabilitation (DR) could support home-based rehabilitation. To develop and implement DR solutions that meet clients' needs and ease the growing pressure on the health care system, it is necessary to provide an overview of existing, relevant, and future solutions shaping the constantly evolving market of technologies for home-based DR.

OBJECTIVE

In this scoping review, we aimed to identify digital technologies for home-based DR, predict new or emerging DR trends, and report on the influences of the COVID-19 pandemic on DR.

METHODS

The scoping review followed the framework of Arksey and O'Malley, with improvements made by Levac et al. A literature search was performed in PubMed, Embase, CINAHL, PsycINFO, and the Cochrane Library. The search spanned January 2015 to January 2022. A bibliometric analysis was performed to provide an overview of the included references, and a co-occurrence analysis identified the technologies for home-based DR. A full-text analysis of all included reviews filtered the trends for home-based DR. A gray literature search supplemented the results of the review analysis and revealed the influences of the COVID-19 pandemic on the development of DR.

RESULTS

A total of 2437 records were included in the bibliometric analysis and 95 in the full-text analysis, and 40 records were included as a result of the gray literature search. Sensors, robotic devices, gamification, virtual and augmented reality, and digital and mobile apps are already used in home-based DR; however, artificial intelligence and machine learning, exoskeletons, and digital and mobile apps represent new and emerging trends. Advantages and disadvantages were displayed for all technologies. The COVID-19 pandemic has led to an increased use of digital technologies as remote approaches but has not led to the development of new technologies.

CONCLUSIONS

Multiple tools are available and implemented for home-based DR; however, some technologies face limitations in the application of home-based rehabilitation. However, artificial intelligence and machine learning could be instrumental in redesigning rehabilitation and addressing future challenges of the health care system, and the rehabilitation sector in particular. The results show the need for feasible and effective approaches to implement DR that meet clients' needs and adhere to framework conditions, regardless of exceptional situations such as the COVID-19 pandemic.

Launching Your VR Neuroscience Laboratory

The proliferation and refinement of affordable virtual reality (VR) technologies and wearable sensors have opened new frontiers in cognitive and behavioral neuroscience. This chapter offers a broad overview of VR for anyone interested in leveraging it as a research tool. In the first section, it examines the fundamental functionalities of VR and outlines important considerations that inform the development of immersive content that stimulates the senses. In the second section, the focus of the discussion shifts to the implementation of VR in the context of the neuroscience lab. Practical advice is offered on adapting commercial, off-the-shelf devices to a researcher's specific purposes. Further, methods are explored for recording, synchronizing, and fusing heterogeneous forms of data obtained through the VR system or add-on sensors, as well as for labeling events and capturing game play. The reader should come away with an understanding of fundamental considerations that need to be addressed in order to launch a successful VR neuroscience research program.

Monitoring Brain Activity in VR: EEG and Neuroimaging

Virtual reality (VR) is increasingly used in neuroscientific research to increase ecological validity without sacrificing experimental control, to provide a richer visual and multisensory experience, and to foster immersion and presence in study participants, which leads to increased motivation and affective experience. But the use of VR, particularly when coupled with neuroimaging or neurostimulation techniques such as electroencephalography (EEG), functional magnetic resonance imaging (fMRI), or transcranial magnetic stimulation (TMS), also yields some challenges. These include intricacies of the technical setup, increased noise in the data due to movement, and a lack of standard protocols for data collection and analysis. This chapter examines current approaches to recording, pre-processing, and analyzing electrophysiological (stationary and mobile EEG), as well as neuroimaging data recorded during VR engagement. It also discusses approaches to synchronizing these data with other data streams. In general, previous research has used a range of different approaches to technical setup and data processing, and detailed reporting of procedures is urgently needed in future studies to ensure comparability and replicability. More support for open-source VR software as well as the development of consensus and best practice papers on issues such as the handling of movement artifacts in mobile EEG-VR will be essential steps in ensuring the continued success of this exciting and powerful technique in neuroscientific research.

Efficacy and Safety of Mirror Therapy for Post-stroke Dysphagia: A Systematic Review and Meta-Analysis

Background

Post-stroke dysphagia is a common symptom after stroke and one of the most frequent and severe complications of stroke. Over the recent years, mirror therapy has generated significant research interest as a non-invasive therapeutic and rehabilitative intervention for post-stroke dysphagia and has been investigated in several randomized controlled trials in single center.

Objective

In this study, we aimed to evaluate the efficacy and safety of mirror therapy for post-stroke dysphagia.

Methods

A total of seven databases were searched comprehensively from inception to the 31 December 2021, including PubMed, the Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Service System (SinoMed), Wan-fang database, and the Chinese Scientific Journals Database (VIP) from inception to 31 December 2021. The primary outcome measure was efficacy, as measured by clinical effectiveness rate. Secondary outcomes included the water swallowing test and the incidence of pneumonia. In addition, we applied the Cochrane Risk of Bias Tool to investigate the risk of bias. Potential publication bias was evaluated by applying Egger's bias indicator test and by assessing the symmetry of data when visualized as funnel plots.

Results

A total of five randomized controlled trials (135 subjects in the experimental group and control group) were found to report the application of mirror therapy for post-stroke dysphagia and were included in this study. No publication bias was detected. Meta-analysis revealed that mirror therapy had a positive effect on the rate of clinical efficacy [odds ratio (OR) = 4.22; 95% confidence interval (CI): 2.3–7.73] and the water swallowing test [mean difference (MD) = −0.76; 95% CI = −1.29 to −0.22]. Moreover, mirror therapy reduced the incidence of pneumonia (OR = 0.13; 95% CI = 0.03–0.49). Subgroup analyses indicated that mirror therapy during the acute phase was robust but was unstable during the convalescent phase. Sensitivity analysis revealed that the results generated by our meta-analysis were robust and stable.

Conclusions

Available evidence appears to suggest that mirror therapy may have a role in the management of post-stroke dysphagia but has yet to be fully confirmed. Existing evidence from clinical trials suggests that evidence relating to the safety of mirror therapy for patients with post-stroke dysphagia is not yet sufficient.

Systematic Review Registration

Identifier: CRD42022302733.

Pantomime of tool use: looking beyond apraxia

Pantomime has a long tradition in clinical neuropsychology of apraxia. It has been much more used by researchers and clinicians to assess tool-use disorders than real tool use. Nevertheless, it remains incompletely understood and has given rise to controversies, such as the involvement of the left inferior parietal lobe or the nature of the underlying cognitive processes. The present article offers a comprehensive framework, with the aim of specifying the neural and cognitive bases of pantomime. To do so, we conducted a series of meta-analyses of brain-lesion, neuroimaging and behavioural studies about pantomime and other related tasks (i.e. real tool use, imitation of meaningless postures and semantic knowledge). The first key finding is that the area PF (Area PF complex) within the left inferior parietal lobe is crucially involved in both pantomime and real tool use as well as in the kinematics component of pantomime. The second key finding is the absence of a well-defined neural substrate for the posture component of pantomime (both grip errors and body-part-as-tool responses). The third key finding is the role played by the intraparietal sulcus in both pantomime and imitation of meaningless postures. The fourth key finding is that the left angular gyrus seems to be critical in the production of motor actions directed towards the body. The fifth key finding is that performance on pantomime is strongly correlated with the severity of semantic deficits. Taken together, these findings invite us to offer a neurocognitive model of pantomime, which provides an integrated alternative to the two hypotheses that dominate the field: The gesture-engram hypothesis and the communicative hypothesis. More specifically, this model assumes that technical reasoning (notably the left area PF), the motor-control system (notably the intraparietal sulcus), body structural description (notably the left angular gyrus), semantic knowledge (notably the polar temporal lobes) and potentially theory of mind (notably the middle prefrontal cortex) work in concert to produce pantomime. The original features of this model open new avenues for understanding the neurocognitive bases of pantomime, emphasizing that pantomime is a communicative task that nevertheless originates in specific tool-use (not motor-related) cognitive processes. .

Implementing technology enhanced real-time action observation therapy in persons with chronic stroke: A pilot study

This pilot study examined a novel technology-enhanced real-time action observation therapy (TERTAOT) of symmetrical bilateral movements in survivors of chronic stroke regardless of their ability to move their paretic limb(s). The TERTAOT used a Kinect XBox One to project mirror images of non-paretic limbs as participants performed symmetrical bilateral motor tasks involving whole-body movements in sitting or standing. The participants received eight weeks of treatment consisting of 30-minutes of conventional physical therapy (balance training, gait training, neuromuscular reeducation, and generalized strength training) and 30-minutes of the TERTAOT protocol per session (three sessions per week for a total of 24 sessions). Ten Meter Walk Test (10MWT), Five Times Sit-to-Stand (5TSTS), Timed Up and Go (TUG), Motor Activity Log - Quality of Movement (QOM) and Amount of Use (AOU) were administered at baseline (pretest), 4 weeks (posttest 1) and 8 weeks (posttest 2) post-TERTAOT, and 3 months after TERTAOT ended (retention). A General Linear Model Repeated Measures (parametric test) or the Friedman Test (non-parametric test) was used to compare outcomes across time points, depending on the normality of data distribution. Bonferroni post-hoc corrections were applied. Seventeen participants completed >80% of TERTAOT sessions without adverse events. The effect of time was significant for 10MWT (p = .001), 5TSTS (p = .001), TUG (p = .005), QOM (p = .001), and AOU (p = .017). TERTAOT may be feasible to be implemented in an outpatient setting. Improvements in functional outcomes including gait, balance, and use of upper limbs were observed after eight weeks of conventional therapy and TERTAOT protocol in survivors of chronic stroke.

The Effect of Virtual Reality Training on Anticipatory Postural Adjustments in Patients with Chronic Nonspecific Low Back Pain: A Preliminary Study

Objectives

This study is aimed at exploring the effects of virtual reality (VR) training on postural control, measured by anticipatory and compensatory postural adjustments (APAs and CPAs, respectively), in patients with chronic nonspecific low back pain (CNLBP) and the potential neuromuscular mechanism of VR training.

Methods

Thirty-four patients were recruited and randomly assigned to the VR group (n = 11), the motor control exercise group (MCE, n = 12) and the control group (CG, n = 11). The VR group received VR training using Kinect Xbox 360 systems and magnetic therapy. Besides magnetic therapy, the participants in the MCE group performed real-time ultrasound-guided abdominal drawing-in maneuver (ADIM) and four-point kneeling exercise. The CG only received magnetic therapy. Surface muscle electromyography (sEMG) was used to record the muscle activities of transverse abdominis (TrA), multifidus (MF), lateral gastrocnemius (LG), and tibialis anterior (TA) during ball-hitting tasks. The muscle activation time and integrals of the electromyography activities (IEMGs) during the APA and CPA stages were calculated and used in the data analysis. The visual analogue scale (VAS) and Oswestry dysfunction index (ODI) scores were also recorded.

Results

A significant interaction effect of time × group was observed on the activation time of TrA (p = 0.018) and MF (p = 0.037). The post-intervention activation time of the TrA was earlier in the VR group (p = 0.029). In contrast, the post-intervention activation time of the MF was significantly delayed in the VR group (p = 0.001). The IEMGs of TrA (p = 0.002) and TA (p = 0.007) during CPA1 significantly decreased only in the VR group after the intervention. The VAS scores of three group participants showed significant decreases after intervention (p < 0.001).

Conclusions

Patients with CNLBP showed reciprocal muscle activation patterns of the TrA and MF muscles after VR training. VR training may be a potential intervention for enhancing the APAs of the patients with CNLBP.

The extrastriate body area is involved in reciprocal imitation of hand gestures, vocalizations, and facial expressions: A univariate and multivariate fMRI study

The extrastriate body area (EBA) in the lateral occipito-temporal cortex has an important role in reciprocal interaction, as it detects congruence between self and other's hand actions. However, it is unclear whether the EBA can detect congruence regardless of the type of action. In the present study, we examined the neural substrate underlying congruence detection of three types of actions: hand gestures, vocalizations, and facial expressions. A univariate analysis revealed a congruency effect, especially for imitating action, for all three types of actions in the EBA. A multi-voxel pattern analysis classifier in the EBA was able to distinguish between initiating interaction from responding to interaction in all experiments. Correspondingly, the congruency effect in the EBA revealed by univariate analysis was stronger for responding to than for initiating interaction. These findings suggest that the EBA might contribute to detect congruence regardless of the body part used (i.e. face or hand) and the type of action (i.e. gestural or vocal). Moreover, initiating and responding to interaction might be processed differently within the EBA. This study highlights the role of the EBA in comparing between self and other's actions beyond hand actions.Running head: Function of EBA in reciprocal imitation.

Neurophysiological Correlates of Cognition as Revealed by Virtual Reality: Delving the Brain with a Synergistic Approach

The synergy of perceptual psychology, technology, and neuroscience can be used to comprehend how virtual reality affects cognition of human brain. Numerous studies have used neuroimaging modalities to assess the cognitive state and response of the brain with various external stimulations. The virtual reality-based devices are well known to incur visual, auditory, and haptic induced perceptions. Neurophysiological recordings together with virtual stimulations can assist in correlating humans’ physiological perception with response in the environment designed virtually. The effective combination of these two has been utilized to study human behavior, spatial navigation performance, and spatial presence, to name a few. Moreover, virtual reality-based devices can be evaluated for the neurophysiological correlates of cognition through neurophysiological recordings. Challenges exist in the integration of real-time neuronal signals with virtual reality-based devices, and enhancing the experience together with real-time feedback and control through neuronal signals. This article provides an overview of neurophysiological correlates of cognition as revealed by virtual reality experience, together with a description of perception and virtual reality-based neuromodulation, various applications, and existing challenges in this field of research.

Grasping performance depends upon the richness of hand feedback

Although visual feedback of the hand allows fast and accurate grasping actions, little is known about whether the nature of feedback of the hand affects performance. We investigated kinematics during precision grasping (with the index finger and thumb) when participants received different levels of hand feedback, with or without visual feedback of the target. Specifically, we compared performance when participants saw (1) no hand feedback; (2) only the two critical points on the index finger and thumb tips; (3) 21 points on all digit tips and hand joints; (4) 21 points connected by a "skeleton", or (5) full feedback of the hand wearing a glove. When less hand feedback was available, participants took longer to execute the movement because they allowed more time to slow the reach and close the hand. When target feedback was unavailable, participants took longer to plan the movement and reached with higher velocity. We were particularly interested in investigating maximum grip aperture (MGA), which can reflect the margin of error that participants allow to compensate for uncertainty. A trend suggested that MGA was smallest when ample feedback was available (skeleton and full hand feedback, regardless of target feedback) and when only essential information about hand and target was provided (2-point hand feedback + target feedback) but increased when non-essential points were included (21-point feedback). These results suggest that visual feedback of the hand affects grasping performance and that, while more feedback is usually beneficial, this is not necessarily always the case.

The medical avatar and its role in neurorehabilitation and neuroplasticity: A review

BACKGROUND

One of the most interesting emerging medical devices is the medical avatar - a digital representation of the patient that can be used toward myriad ends, the full potential of which remains to be explored. Medical avatars have been instantiated as telemedical tools used to establish a representation of the patient in tele-space, upon which data about the patient's health can be represented and goals and progress can be visually tracked. Manipulation of the medical avatar has also been explored as a means of increasing motivation and inducing neural plasticity.

OBJECTIVE

The article reviews the literature on body representation, simulation, and action-observation and explores how these components of neurorehabilitation are engaged by an avatar-based self-representation.

METHODS

Through a review of the literature on body representation, simulation, and action-observation and a review of how these components of neurorehabilitation can be engaged and manipulated with an avatar, the neuroplastic potential of the medical avatar is explored. Literature on the use of the medical avatar for neurorehabilitation is also reviewed.

RESULTS

This review demonstrates that the medical avatar has vast potentialities in neurorehabilitation and that further research on its use and effect is needed.

Action, observation or imitation of virtual hand movement affect differently regions of the mirror neuron system and the default mode network

Virtual reality (VR)-based paradigms use visual stimuli that can modulate visuo-motor networks leading to the stimulation of brain circuits. The aims of this study were to compare the changes in blood-oxygenation level dependent (BOLD) signal when watching and imitating moving real (RH) and virtual hands (VH) in 11 healthy participants (HP). No differences were found between the observation of RH or VH making this VR-based experiment a promising tool for rehabilitation protocols. VH-imitation involved more the ventral premotor cortex (vPMC) as part of the mirror neuron system (MNS) compared to execution and VH-observation conditions. The dorsal-anterior Precuneus (da-Pcu) as part of the Precuneus/posterior Cingulate Cortex (Pcu/pCC) complex, a key node of the Default Mode Network (DMN), was also less deactivated and therefore more involved. These results may reflect the dual visuo-motor roles for the vPMC and the implication of the da-Pcu in the reallocation of attentional and neural resources for bimodal task management. The ventral Pcu/pCC was deactivated regardless of the condition confirming its role in self-reference processes. Imitation of VH stimuli can then modulate the activation of specific areas including those belonging to the MNS and the DMN.

Virtual Reality Enhances Gait in Cerebral Palsy: A Training Dose-Response Meta-Analysis

Virtual-reality-based training can influence gait recovery in children with cerebral palsy. A consensus concerning its influence on spatiotemporal gait parameters and effective training dosage is still warranted. This study analyzes the influence of virtual-reality training (relevant training dosage) on gait recovery in children with cerebral palsy. A search was performed by two reviewers according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines on nine databases: PEDro, EBSCO, PubMed, Cochrane, Web of Science, EMBASE, ICI, Scopus, and PROQUEST. Of 989 records, 16 studies involving a total of 274 children with cerebral palsy met our inclusion criteria. Eighty-eight percent of the studies reported significant enhancements in gait performance after training with virtual reality. Meta-analyses revealed positive effects of virtual-reality training on gait velocity (Hedge's g = 0.68), stride length (0.30), cadence (0.66), and gross motor function measure (0.44). Subgroup analysis reported a training duration of 20–30 min per session, ≤4 times per week across ≥8 weeks to allow maximum enhancements in gait velocity. This study provides preliminary evidence for the beneficial influence of virtual-reality training in gait rehabilitation for children with cerebral palsy.

Virtual reality experiences, embodiment, videogames and their dimensions in neurorehabilitation

Background

In the context of stroke rehabilitation, new training approaches mediated by virtual reality and videogames are usually discussed and evaluated together in reviews and meta-analyses. This represents a serious confounding factor that is leading to misleading, inconclusive outcomes in the interest of validating these new solutions.

Main body

Extending existing definitions of virtual reality, in this paper I put forward the concept of virtual reality experience (VRE), generated by virtual reality systems (VRS; i.e. a group of variable technologies employed to create a VRE). Then, I review the main components composing a VRE, and how they may purposely affect the mind and body of participants in the context of neurorehabilitation. In turn, VRS are not anymore exclusive from VREs but are currently used in videogames and other human-computer interaction applications in different domains. Often, these other applications receive the name of virtual reality applications as they use VRS. However, they do not necessarily create a VRE. I put emphasis on exposing fundamental similarities and differences between VREs and videogames for neurorehabilitation. I also recommend describing and evaluating the specific features encompassing the intervention rather than evaluating virtual reality or videogames as a whole.

Conclusion

This disambiguation between VREs, VRS and videogames should help reduce confusion in the field. This is important for databases searches when looking for specific studies or building metareviews that aim at evaluating the efficacy of technology-mediated interventions.

Virtual Reality as a Vehicle to Empower Motor-Cognitive Neurorehabilitation

In this paper, we advocate the combination of four key ingredients that we believe are necessary to design long-lasting effective treatments for neurorehabilitation: (i) motor-cognitive training, (ii) evidence-based neuroscience principles, in particular those related to body perception, (iii) motivational games, and (iv) empowerment techniques. Then, we propose virtual reality (VR) as the appropriate medium to encompass all the requirements mentioned above. VR is arguably one of the most suitable technologies for neurorehabilitation able to integrate evidence-based neurorehabilitation techniques and neuroscience principles into motivating training approaches that promote self-management by empowering patients to own their recovery process. We discuss the advantages and challenges of such an approach on several exemplary applications and outline directions for future developments. We strongly believe that the combination of positive psychology and positive technology mediated by VR-based interventions can heavily impact the rehabilitation outcomes of motor-cognitive functions along all the stages of the rehabilitation path.

Mirror therapy for improving motor function after stroke

BACKGROUND

Mirror therapy is used to improve motor function after stroke. During mirror therapy, a mirror is placed in the person's midsagittal plane, thus reflecting movements of the non-paretic side as if it were the affected side.

OBJECTIVES

To summarise the effectiveness of mirror therapy compared with no treatment, placebo or sham therapy, or other treatments for improving motor function and motor impairment after stroke. We also aimed to assess the effects of mirror therapy on activities of daily living, pain, and visuospatial neglect.

SEARCH METHODS

We searched the Cochrane Stroke Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, AMED, PsycINFO and PEDro (last searched 16 August 2017). We also handsearched relevant conference proceedings, trials and research registers, checked reference lists, and contacted trialists, researchers and experts in our field of study.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and randomised cross-over trials comparing mirror therapy with any control intervention for people after stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials based on the inclusion criteria, documented the methodological quality, assessed risks of bias in the included studies, and extracted data. We assessed the quality of the evidence using the GRADE approach. We analysed the results as standardised mean differences (SMDs) or mean differences (MDs) for continuous variables, and as odds ratios (ORs) for dichotomous variables.

MAIN RESULTS

We included 62 studies with a total of 1982 participants that compared mirror therapy with other interventions. Of these, 57 were randomised controlled trials and five randomised cross-over trials. Participants had a mean age of 59 years (30 to 73 years). Mirror therapy was provided three to seven times a week, between 15 and 60 minutes for each session for two to eight weeks (on average five times a week, 30 minutes a session for four weeks).When compared with all other interventions, we found moderate-quality evidence that mirror therapy has a significant positive effect on motor function (SMD 0.47, 95% CI 0.27 to 0.67; 1173 participants; 36 studies) and motor impairment (SMD 0.49, 95% CI 0.32 to 0.66; 1292 participants; 39 studies). However, effects on motor function are influenced by the type of control intervention. Additionally, based on moderate-quality evidence, mirror therapy may improve activities of daily living (SMD 0.48, 95% CI 0.30 to 0.65; 622 participants; 19 studies). We found low-quality evidence for a significant positive effect on pain (SMD -0.89, 95% CI -1.67 to -0.11; 248 participants; 6 studies) and no clear effect for improving visuospatial neglect (SMD 1.06, 95% CI -0.10 to 2.23; 175 participants; 5 studies). No adverse effects were reported.

AUTHORS' CONCLUSIONS

The results indicate evidence for the effectiveness of mirror therapy for improving upper extremity motor function, motor impairment, activities of daily living, and pain, at least as an adjunct to conventional rehabilitation for people after stroke. Major limitations are small sample sizes and lack of reporting of methodological details, resulting in uncertain evidence quality.

Neural Patterns of Reorganization after Intensive Robot-Assisted Virtual Reality Therapy and Repetitive Task Practice in Patients with Chronic Stroke

Several approaches to rehabilitation of the hand following a stroke have emerged over the last two decades. These treatments, including repetitive task practice (RTP), robotically assisted rehabilitation and virtual rehabilitation activities, produce improvements in hand function but have yet to reinstate function to pre-stroke levels-which likely depends on developing the therapies to impact cortical reorganization in a manner that favors or supports recovery. Understanding cortical reorganization that underlies the above interventions is therefore critical to inform how such therapies can be utilized and improved and is the focus of the current investigation. Specifically, we compare neural reorganization elicited in stroke patients participating in two interventions: a hybrid of robot-assisted virtual reality (RAVR) rehabilitation training and a program of RTP training. Ten chronic stroke subjects participated in eight 3-h sessions of RAVR therapy. Another group of nine stroke subjects participated in eight sessions of matched RTP therapy. Functional magnetic resonance imaging (fMRI) data were acquired during paretic hand movement, before and after training. We compared the difference between groups and sessions (before and after training) in terms of BOLD intensity, laterality index of activation in sensorimotor areas, and the effective connectivity between ipsilesional motor cortex (iMC), contralesional motor cortex, ipsilesional primary somatosensory cortex (iS1), ipsilesional ventral premotor area (iPMv), and ipsilesional supplementary motor area. Last, we analyzed the relationship between changes in fMRI data and functional improvement measured by the Jebsen Taylor Hand Function Test (JTHFT), in an attempt to identify how neurophysiological changes are related to motor improvement. Subjects in both groups demonstrated motor recovery after training, but fMRI data revealed RAVR-specific changes in neural reorganization patterns. First, BOLD signal in multiple regions of interest was reduced and re-lateralized to the ipsilesional side. Second, these changes correlated with improvement in JTHFT scores. Our findings suggest that RAVR training may lead to different neurophysiological changes when compared with traditional therapy. This effect may be attributed to the influence that augmented visual and haptic feedback during RAVR training exerts over higher-order somatosensory and visuomotor areas.

The Effects of Mirror Feedback during Target Directed Movements on Ipsilateral Corticospinal Excitability

Mirror visual feedback (MVF) training is a promising technique to promote activation in the lesioned hemisphere following stroke, and aid recovery. However, current outcomes of MVF training are mixed, in part, due to variability in the task undertaken during MVF. The present study investigated the hypothesis that movements directed toward visual targets may enhance MVF modulation of motor cortex (M1) excitability ipsilateral to the trained hand compared to movements without visual targets. Ten healthy subjects participated in a 2 × 2 factorial design in which feedback (veridical, mirror) and presence of a visual target (target present, target absent) for a right index-finger flexion task were systematically manipulated in a virtual environment. To measure M1 excitability, transcranial magnetic stimulation (TMS) was applied to the hemisphere ipsilateral to the trained hand to elicit motor evoked potentials (MEPs) in the untrained first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles at rest prior to and following each of four 2-min blocks of 30 movements (B1–B4). Targeted movement kinematics without visual feedback was measured before and after training to assess learning and transfer. FDI MEPs were decreased in B1 and B2 when movements were made with veridical feedback and visual targets were absent. FDI MEPs were decreased in B2 and B3 when movements were made with mirror feedback and visual targets were absent. FDI MEPs were increased in B3 when movements were made with mirror feedback and visual targets were present. Significant MEP changes were not present for the uninvolved ADM, suggesting a task-specific effect. Analysis of kinematics revealed learning occurred in visual target-directed conditions, but transfer was not sensitive to mirror feedback. Results are discussed with respect to current theoretical mechanisms underlying MVF-induced changes in ipsilateral excitability.

Virtual Reality for Research in Social Neuroscience

The emergence of social neuroscience has significantly advanced our understanding of the relationship that exists between social processes and their neurobiological underpinnings. Social neuroscience research often involves the use of simple and static stimuli lacking many of the potentially important aspects of real world activities and social interactions. Whilst this research has merit, there is a growing interest in the presentation of dynamic stimuli in a manner that allows researchers to assess the integrative processes carried out by perceivers over time. Herein, we discuss the potential of virtual reality for enhancing ecological validity while maintaining experimental control in social neuroscience research. Virtual reality is a technology that allows for the creation of fully interactive, three-dimensional computerized models of social situations that can be fully controlled by the experimenter. Furthermore, the introduction of interactive virtual characters—either driven by a human or by a computer—allows the researcher to test, in a systematic and independent manner, the effects of various social cues. We first introduce key technical features and concepts related to virtual reality. Next, we discuss the potential of this technology for enhancing social neuroscience protocols, drawing on illustrative experiments from the literature.

Network interactions underlying mirror feedback in stroke: A dynamic causal modeling study

Mirror visual feedback (MVF) is potentially a powerful tool to facilitate recovery of disordered movement and stimulate activation of under-active brain areas due to stroke. The neural mechanisms underlying MVF have therefore been a focus of recent inquiry. Although it is known that sensorimotor areas can be activated via mirror feedback, the network interactions driving this effect remain unknown. The aim of the current study was to fill this gap by using dynamic causal modeling to test the interactions between regions in the frontal and parietal lobes that may be important for modulating the activation of the ipsilesional motor cortex during mirror visual feedback of unaffected hand movement in stroke patients. Our intent was to distinguish between two theoretical neural mechanisms that might mediate ipsilateral activation in response to mirror-feedback: transfer of information between bilateral motor cortices versus recruitment of regions comprising an action observation network which in turn modulate the motor cortex. In an event-related fMRI design, fourteen chronic stroke subjects performed goal-directed finger flexion movements with their unaffected hand while observing real-time visual feedback of the corresponding (veridical) or opposite (mirror) hand in virtual reality. Among 30 plausible network models that were tested, the winning model revealed significant mirror feedback-based modulation of the ipsilesional motor cortex arising from the contralesional parietal cortex, in a region along the rostral extent of the intraparietal sulcus. No winning model was identified for the veridical feedback condition. We discuss our findings in the context of supporting the latter hypothesis, that mirror feedback-based activation of motor cortex may be attributed to engagement of a contralateral (contralesional) action observation network. These findings may have important implications for identifying putative cortical areas, which may be targeted with non-invasive brain stimulation as a means of potentiating the effects of mirror training.

Auditory and visual cueing modulate cycling speed of older adults and persons with Parkinson's disease in a Virtual Cycling (V-Cycle) system

BACKGROUND

Evidence based virtual environments (VEs) that incorporate compensatory strategies such as cueing may change motor behavior and increase exercise intensity while also being engaging and motivating. The purpose of this study was to determine if persons with Parkinson's disease and aged matched healthy adults responded to auditory and visual cueing embedded in a bicycling VE as a method to increase exercise intensity.

METHODS

We tested two groups of participants, persons with Parkinson's disease (PD) (n = 15) and age-matched healthy adults (n = 13) as they cycled on a stationary bicycle while interacting with a VE. Participants cycled under two conditions: auditory cueing (provided by a metronome) and visual cueing (represented as central road markers in the VE). The auditory condition had four trials in which auditory cues or the VE were presented alone or in combination. The visual condition had five trials in which the VE and visual cue rate presentation was manipulated. Data were analyzed by condition using factorial RMANOVAs with planned t-tests corrected for multiple comparisons.

RESULTS

There were no differences in pedaling rates between groups for both the auditory and visual cueing conditions. Persons with PD increased their pedaling rate in the auditory (F 4.78, p = 0.029) and visual cueing (F 26.48, p < 0.000) conditions. Age-matched healthy adults also increased their pedaling rate in the auditory (F = 24.72, p < 0.000) and visual cueing (F = 40.69, p < 0.000) conditions. Trial-to-trial comparisons in the visual condition in age-matched healthy adults showed a step-wise increase in pedaling rate (p = 0.003 to p < 0.000). In contrast, persons with PD increased their pedaling rate only when explicitly instructed to attend to the visual cues (p < 0.000).

CONCLUSIONS

An evidenced based cycling VE can modify pedaling rate in persons with PD and age-matched healthy adults. Persons with PD required attention directed to the visual cues in order to obtain an increase in cycling intensity. The combination of the VE and auditory cues was neither additive nor interfering. These data serve as preliminary evidence that embedding auditory and visual cues to alter cycling speed in a VE as method to increase exercise intensity that may promote fitness.

Considerations in the efficacy and effectiveness of virtual reality interventions for stroke rehabilitation: moving the field forward

In the past 2 decades, researchers have demonstrated the potential for virtual reality (VR) technologies to provide engaging and motivating environments for stroke rehabilitation interventions. Much of the research has been focused on the exploratory phase, and jumps to intervention efficacy trials and scale-up evaluation have been made with limited understanding of the active ingredients in a VR intervention for stroke. The rapid pace of technology development is an additional challenge for this emerging field, providing a moving target for researchers developing and evaluating potential VR technologies. Recent advances in customized games and cutting-edge technology used for VR are beginning to allow for researchers to understand and control aspects of the intervention related to motivation, engagement, and motor control and learning. This article argues for researchers to take a progressive, step-wise approach through the stages of intervention development using evidence-based principles, take advantage of the data that can be obtained, and utilize measurement tools to design effective VR interventions for stroke rehabilitation that can be assessed through carefully designed efficacy and effectiveness trials. This article is motivated by the recent calls in the field of rehabilitation clinical trials research for carefully structured clinical trials that have progressed through the phases of research.

Mirrored feedback in chronic stroke: recruitment and effective connectivity of ipsilesional sensorimotor networks

BACKGROUND

Mirrored feedback has potential as a therapeutic intervention to restore hand function after stroke. However, the functional (effective) connectivity of neural networks involved in processing mirrored feedback after stroke is not known.

OBJECTIVE

To determine if regions recruited by mirrored feedback topographically overlap with those involved in control of the paretic hand and to identify the effective connectivity of activated nodes within the mirrored feedback network.

METHODS

Fifteen patients with chronic stroke performed a finger flexion task with their unaffected hand during event-related functional magnetic resonance imaging (fMRI). Real-time hand kinematics was recorded during fMRI and used to actuate hand models presented in virtual reality (VR). Visual feedback of the unaffected hand motion was manipulated pseudorandomly by either actuating the VR hand corresponding to the moving unaffected side (veridical feedback) or the affected side (mirrored feedback). In 2 control conditions, the VR hands were replaced with moving nonanthropomorphic shapes.

RESULTS

Mirrored feedback was associated with significant activation of regions within and outside the ipsilesional sensorimotor cortex, overlapping with areas engaged when patients performed the task with their affected hand. Effective connectivity analysis showed a significantly interconnected ipsilesional somatosensory and motor cortex in the mirrored feedback condition.

CONCLUSIONS

Mirrored feedback recruits ipsilesional brain areas relevant for control of the affected hand. These data provide a neurophysiological basis by which mirrored feedback may be beneficial as a therapy for restoring function after stroke.

Resting state functional connectivity and task-related effective connectivity changes after upper extremity rehabilitation: a pilot study

In this study we investigated the effect of 2 weeks of robot-aided virtual reality therapy for the paretic upper limb in stroke patients on changes in brain activation. Brain activation was acquired during the resting state and during visually-guided hand movement. fMRI analysis focused on characterizing functional connectivity with ipsilesional primary motor cortex (iM1) at rest and during execution of paretic hand movement. Two subjects who sustained a stroke more than 6 months ago participated. Before and after the training period, motor function was evaluated (Wolf Motor Function Test [WMFT], Jebsen Test of Hand Function [JTHF]). After the training period, clinical outcomes (WMFT and JTHF) improved in both subjects. The resting state functional connectivity (rsFC) maps and task-related functional connectivity with iM1 showed different magnitudes of activation, however, the general directionality of the pattern (increases versus decreases) was similar. Specifically, both the rsFC and the task-related functional connectivity between iM1 and contralesional primary motor cortex (cM1) decreased after the therapy for the first subject and increased for the second subject. Our preliminary data suggest that resting state functional connectivity may be a useful measure of brain reorganization, particularly for subjects with limited volitional control of the paretic limb.

Visuomotor discordance during visually-guided hand movement in virtual reality modulates sensorimotor cortical activity in healthy and hemiparetic subjects

We investigated neural effects of visuomotor discordances during visually-guided finger movements. A functional magnetic resonance imaging (fMRI)-compatible data glove was used to actuate (in real-time) virtual hand models shown on a display in first person perspective. In Experiment 1, we manipulated virtual hand motion to simulate either hypometric or unintentional (actuation of a mismatched finger) feedback of sequential finger flexion in healthy subjects. Analysis of finger motion revealed no significant differences in movement behavior across conditions, suggesting that between-condition differences in brain activity could only be attributed to varying modes of visual feedback rather than motor output. Hypometric feedback and mismatched finger feedback (relative to veridical) were associated with distinct activation. Hypometric feedback was associated with activation in the contralateral motor cortex. Mismatched feedback was associated with activation in bilateral ventral premotor, left dorsal premotor, and left occipitotemporal cortex. The time it took the subject to evaluate visuomotor discordance was positively correlated with activation in bilateral supplementary motor area, bilateral insula, right postcentral gyrus, bilateral dorsal premotor areas, and bilateral posterior parietal lobe. In Experiment 2, we investigated the effects of hypo- and hypermetric visual feedback in three stroke subjects. We observed increased activation of ipsilesional motor cortex in both hypometric and hypermetric feedback conditions. Our data indicate that manipulation of visual feedback of one's own hand movement may be used to facilitate activity in select brain networks. We suggest that these effects can be exploited in neurorehabilition to enhance the processes of brain reorganization after injury and, specifically, might be useful in aiding recovery of hand function in patients during virtual reality-based training.

Mechanisms of neural reorganization in chronic stroke subjects after virtual reality training

This study investigates patterns of brain reorganization in chronic stroke subjects after two weeks of robot-assisted arm and hand training in virtual reality (VR). Four subjects were studied with event-related fMRI while doing simple paretic hand finger movements before (double baseline) and after training. Bilateral hand movements were recorded and used to provide real-time feedback to subjects during scanning to eliminate performance confounds on fMRI results. The kinematic parameters of each movement were also used in the general linear model with the BOLD signal to investigate training-induced changes in neuromotor coupling. Univariate analysis showed an increase in BOLD signal in the ipsilesional hemisphere in two subjects and a decrease in activity in the other two subjects. Seed voxel based functional connectivity analysis revealed an increase in connectivity between ipsilesional motor cortex and bilateral sensorimotor cortex during finger movements in all four subjects. Hemispheric laterality index values showed a tendency to decrease reflecting a reduction in the over-dominance of the contralesional hemisphere. The study is novel in terms of 1) tracking finger movement during a motor task in the scanner, 2) monitoring motor performance during the experiment and 3) giving online visual feedback of subjects' movement. This pilot study introduces a novel approach to study neural plasticity by combining measures of regional intensity, interregional interactions (using functional connectivity analysis and hemispheric laterality index), and modulation in the strength of neuromotor coupling.

The Neurorehabilitation Training Toolkit (NTT): A Novel Worldwide Accessible Motor Training Approach for At-Home Rehabilitation after Stroke

After stroke, enduring rehabilitation is required for maximum recovery, and ideally throughout life to prevent functional deterioration. Hence we developed a new concept for at-home low-cost motor rehabilitation, the NTT, an Internet-based interactive system for upper-limb rehabilitation. In this paper we present the NTT design concepts, its implementation and a proof of concept study with 10 healthy participants. The NTT brings together concepts of optimal learning, engagement, and storytelling to deliver a personalized training to its users. In this study we evaluate the feasibility of NTT as a tool capable of automatically assessing and adapting to its user. This is achieved by means of a psychometric study where we show that the NTT is able to assess movement kinematics-movement smoothness, range of motion, arm displacement and arm coordination-in healthy users. Subsequently, a modeling approach is presented to understand how the measured movement kinematics relate to training parameters, and how these can be modified to adapt the training to meet the needs of patients. Finally, an adaptive algorithm for the personalization of training considering motivational and performance aspects is proposed. In the next phase we will deploy and evaluate the NTT with stroke patients at their homes.

Multisensory stimulation in stroke rehabilitation

The brain has a large capacity for automatic simultaneous processing and integration of sensory information. Combining information from different sensory modalities facilitates our ability to detect, discriminate, and recognize sensory stimuli, and learning is often optimal in a multisensory environment. Currently used multisensory stimulation methods in stroke rehabilitation include motor imagery, action observation, training with a mirror or in a virtual environment, and various kinds of music therapy. Non-invasive brain stimulation has showed promising preliminary results in aphasia and neglect. Patient heterogeneity and the interaction of age, gender, genes, and environment are discussed. Randomized controlled longitudinal trials starting earlier post-stroke are needed. The advance in brain network science and neuroimaging enabling longitudinal studies of structural and functional networks are likely to have an important impact on patient selection for specific interventions in future stroke rehabilitation. It is proposed that we should pay more attention to age, gender, and laterality in clinical studies.

Mirror therapy for improving motor function after stroke

BACKGROUND

Mirror therapy is used to improve motor function after stroke. During mirror therapy, a mirror is placed in the patient's midsagittal plane, thus reflecting movements of the non-paretic side as if it were the affected side.

OBJECTIVES

To summarise the effectiveness of mirror therapy for improving motor function, activities of daily living, pain and visuospatial neglect in patients after stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group's Trials Register (June 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 2), MEDLINE (1950 to June 2011), EMBASE (1980 to June 2011), CINAHL (1982 to June 2011), AMED (1985 to June 2011), PsycINFO (1806 to June 2011) and PEDro (June 2011). We also handsearched relevant conference proceedings, trials and research registers, checked reference lists and contacted trialists, researchers and experts in our field of study.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and randomised cross-over trials comparing mirror therapy with any control intervention for patients after stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials based on the inclusion criteria, documented the methodological quality of studies and extracted data. We analysed the results as standardised mean differences (SMDs) for continuous variables.

MAIN RESULTS

We included 14 studies with a total of 567 participants that compared mirror therapy with other interventions. When compared with all other interventions, mirror therapy may have a significant effect on motor function (post-intervention data: SMD 0.61; 95% confidence interval (CI) 0.22 to 1.0; P = 0.002; change scores: SMD 1.04; 95% CI 0.57 to 1.51; P < 0.0001). However, effects on motor function are influenced by the type of control intervention. Additionally, mirror therapy may improve activities of daily living (SMD 0.33; 95% CI 0.05 to 0.60; P = 0.02). We found a significant positive effect on pain (SMD -1.10; 95% CI -2.10 to -0.09; P = 0.03) which is influenced by patient population. We found limited evidence for improving visuospatial neglect (SMD 1.22; 95% CI 0.24 to 2.19; P = 0.01). The effects on motor function were stable at follow-up assessment after six months.

AUTHORS' CONCLUSIONS

The results indicate evidence for the effectiveness of mirror therapy for improving upper extremity motor function, activities of daily living and pain, at least as an adjunct to normal rehabilitation for patients after stroke. Limitations are due to small sample sizes of most included studies, control interventions that are not used routinely in stroke rehabilitation and some methodological limitations of the studies.

Virtual reality as a tool for evaluation of repetitive rhythmic movements in the elderly and Parkinson's disease patients

This work presents an immersive Virtual Reality (VR) system to evaluate, and potentially treat, the alterations in rhythmic hand movements seen in Parkinson's disease (PD) and the elderly (EC), by comparison with healthy young controls (YC). The system integrates the subjects into a VR environment by means of a Head Mounted Display, such that subjects perceive themselves in a virtual world consisting of a table within a room. In this experiment, subjects are presented in 1(st) person perspective, so that the avatar reproduces finger tapping movements performed by the subjects. The task, known as the finger tapping test (FT), was performed by all three subject groups, PD, EC and YC. FT was carried out by each subject on two different days (sessions), one week apart. In each FT session all subjects performed FT in the real world (FT(REAL)) and in the VR (FT(VR)); each mode was repeated three times in randomized order. During FT both the tapping frequency and the coefficient of variation of inter-tap interval were registered. FT(VR) was a valid test to detect differences in rhythm formation between the three groups. Intra-class correlation coefficients (ICC) and mean difference between days for FT(VR) (for each group) showed reliable results. Finally, the analysis of ICC and mean difference between FT(VR) vs FT(REAL), for each variable and group, also showed high reliability. This shows that FT evaluation in VR environments is valid as real world alternative, as VR evaluation did not distort movement execution and detects alteration in rhythm formation. These results support the use of VR as a promising tool to study alterations and the control of movement in different subject groups in unusual environments, such as during fMRI or other imaging studies.

Remapping in the ipsilesional motor cortex after VR-based training: a pilot fMRI study

In a single case longitudinal study, a 70 year old female subject who has had a subcortical stroke 8 years prior, was tested three times in fMRI using an interactive MRI-compatible VR environment. The subject performed sequential finger movements with her right (unaffected) hand. Her hand motion (recorded with the data glove) animated either the ipsilateral (corresponding) or contralateral (mirrored) virtual hand model. In a visual feedback control condition, the virtual hand models were replaced with ellipsoids. In between the second and third session, the patient participated in an intensive, two-week long VR-based training of her affected upper extremity. When comparing activation in the mirrored versus the non-mirrored virtual visual feedback condition, no significant activation was noted in motor or premotor areas in the baseline 1 or baseline 2 sessions. However, increased activation in the ipsilesional motor cortex occurred as a result of training, despite the absence of active involvement of the ipsilesional motor cortex in this condition. The left motor cortex was also recruited in this condition (though weaker) despite the subtracted out ellipsoid condition (in which subjects also moved their hand). Thus, the contralateral (mirrored) visual feedback may have had a facilitory effect bilaterally. These findings might have some important implications for the development of novel therapies in the acute phase, when paresis and the potential for neural remapping are greatest.

ALE meta-analysis of action observation and imitation in the human brain

Over the last decade, many neuroimaging studies have assessed the human brain networks underlying action observation and imitation using a variety of tasks and paradigms. Nevertheless, questions concerning which areas consistently contribute to these networks irrespective of the particular experimental design and how such processing may be lateralized remain unresolved. The current study aimed at identifying cortical areas consistently involved in action observation and imitation by combining activation likelihood estimation (ALE) meta-analysis with probabilistic cytoarchitectonic maps. Meta-analysis of 139 functional magnetic resonance and positron emission tomography experiments revealed a bilateral network for both action observation and imitation. Additional subanalyses for different effectors within each network revealed highly comparable activation patterns to the overall analyses on observation and imitation, respectively, indicating an independence of these findings from potential confounds. Conjunction analysis of action observation and imitation meta-analyses revealed a bilateral network within frontal premotor, parietal, and temporo-occipital cortex. The most consistently rostral inferior parietal area was PFt, providing evidence for a possible homology of this region to macaque area PF. The observation and imitation networks differed particularly with respect to the involvement of Broca's area: whereas both networks involved a caudo-dorsal part of BA 44, activation during observation was most consistent in a more rostro-dorsal location, i.e., dorsal BA 45, while activation during imitation was most consistent in a more ventro-caudal aspect, i.e., caudal BA 44. The present meta-analysis thus summarizes and amends previous descriptions of the human brain networks related to action observation and imitation.

Sensorimotor training in virtual reality: a review

Recent experimental evidence suggests that rapid advancement of virtual reality (VR) technologies has great potential for the development of novel strategies for sensorimotor training in neurorehabilitation. We discuss what the adaptive and engaging virtual environments can provide for massive and intensive sensorimotor stimulation needed to induce brain reorganization.Second, discrepancies between the veridical and virtual feedback can be introduced in VR to facilitate activation of targeted brain networks, which in turn can potentially speed up the recovery process. Here we review the existing experimental evidence regarding the beneficial effects of training in virtual environments on the recovery of function in the areas of gait,upper extremity function and balance, in various patient populations. We also discuss possible mechanisms underlying these effects. We feel that future research in the area of virtual rehabilitation should follow several important paths. Imaging studies to evaluate the effects of sensory manipulation on brain activation patterns and the effect of various training parameters on long term changes in brain function are needed to guide future clinical inquiry. Larger clinical studies are also needed to establish the efficacy of sensorimotor rehabilitation using VR in various clinical populations and most importantly, to identify VR training parameters that are associated with optimal transfer to real-world functional improvements.