The Activation of the Mirror Neuron System during Action Observation and Action Execution with Mirror Visual Feedback in Stroke: A Systematic Review

Identification of Subtypes of Post-Stroke and Neurotypical Gait Behaviors Using Neural Network Analysis of Gait Cycle Kinematics

Gait impairment post-stroke is highly heterogeneous. Prior studies classified heterogeneous gait patterns into subgroups using peak kinematics, kinetics, or spatiotemporal variables. A limitation of this approach is the need to select discrete features in the gait cycle. Using continuous gait cycle data, we accounted for differences in magnitude and timing of kinematics. Here, we propose a machine-learning pipeline combining supervised and unsupervised learning. We first trained a Convolutional Neural Network and a Temporal Convolutional Network to extract features that distinguish impaired from neurotypical gait. Then, we used unsupervised time-series k-means and Gaussian Mixture Models to identify gait clusters. We tested our pipeline using kinematic data of 28 neurotypical and 39 individuals post-stroke. We assessed differences between clusters using ANOVA. We identified two neurotypical gait clusters (C1, C2). C1: normative gait pattern. C2: shorter stride time. We observed three post-stroke gait clusters (S1, S2, S3). S1: mild impairment and increased bilateral knee flexion during loading response. S2: moderate impairment, slow speed, short steps, increased knee flexion during stance bilaterally, and reduced paretic knee flexion during swing. S3: mild impairment, asymmetric swing time, increased ankle abduction during the gait cycle, and reduced dorsiflexion bilaterally. Our results indicate that joint kinematics post-stroke are mostly distinct from controls, and highlight kinematic impairments in the non-paretic limb. The post-stroke clusters showed distinct impairments that would require different interventions, providing additional information for clinicians about rehabilitation targets.

Impact of Observation Duration in Action Observation Therapy: Manual Dexterity, Mirror Neuron System Activity, and Subjective Psychomotor Effort in Healthy Adults

Background/Objectives: Action observation therapy (AOT) has gained attention as a rehabilitation method for motor function recovery following nerve injury. Although the total observation time and daily session duration have been studied, the effective observation duration per trial remains unclear. This study examined the effect of different observation durations on manual dexterity, mirror neuron system activity, and subjective psychomotor effort in healthy adults. Methods: Twenty-four healthy right-handed adults participated in this crossover study under four conditions: observing ball rotations with the dominant hand for one, two, or three minutes, or geometric patterns (control) for two minutes. The outcomes included maximum rotations and errors by both hands during a ball rotation task and interpersonal motor resonance (IMR), indicating mirror neuron system activity. These measures were compared before and after intervention. Subjective ratings of concentration, physical fatigue, and mental fatigue were assessed post-intervention. Results: Rotation performance significantly increased for the intervention hand after a 2 min observation and showed a notable effect (p = 0.113, r = 0.48) for the non-intervention hand after a 3 min observation compared to the control. The IMR was significantly greater during the 2 min observation than in the control. Compared to the 1 min observation, the 2 min and 3 min observations resulted in higher mental fatigue, and the 3 min observation showed lower concentration levels. Conclusions: These findings indicate that the observation duration has varying effects on manual dexterity and mirror neuron system activity, with optimal effects observed at specific time intervals while also highlighting the relationship between observational learning and psychomotor effort.

Effects of mirror visual observation priming on upper extremity motor recovery after stroke: a pilot randomized controlled trial

OBJECTIVE

To investigate the priming effects of mirror visual observation (MVO) on upper extremity (UE) motor recover after stroke.

DESIGN

Randomized, controlled, observer -blinded study.

SETTING

Rehabilitation Medicine Department in Tertiary Hospital.

PARTICIPANTS

Twenty individuals with first unilateral stroke within 1 week to 6 months.

INTERVENTION

Participants were randomly divided into two groups: (1) the experimental group (EG) receiving MVO with task-oriented training (MVO+TOT); (2) the control group (CG) receiving sham MVO+TOT. The intervention consisted of 30 minutes of MVO or sham MVO, a 10-minute break, and 30 minutes of TOT daily, five days a week, for three weeks.

MAIN OUTCOME MEASURES

The primary outcome was the Fugl-Meyer Assessment Upper Extremity Motor Function Subscale (FMA_UE). The change of FMA_UE (ΔFMA_UE) before and after the intervention was assessed for clinical significance. The secondary outcomes included grip strength, the Action Research Arm Test (ARAT), and the Modified Barthel Index (MBI).

RESULTS

All patients completed the trial without adverse reactions. The EG had a better treatment experience than the CG. Both groups showed improvements in FMA_UE, grip strength, ARAT, and MBI scores from baseline (P<0.05 for all). Post-intervention, there were no differences between the groups in grip strength, ARAT, and MBI scores (P>0.05 for all). However, the EG showed a better improvement in FMA_UE scores compared to the CG (P=0.044). The ΔFMA_UE of both groups surpassed the minimal clinically important difference (MCID). The average ΔFMA_UE difference between the groups was 10.80 (95% CI: 6.31 to 15.29), exceeding the MCID with statistical significance (P<0.001).

CONCLUSIONS

MVO demonstrates a priming effect that enhances the recovery of UE motor impairments post-stroke with clinical significance.

Signal Characteristics, Motor Cortex Engagement, and Classification Performance of Combined Action Observation, Motor Imagery and SSMVEP (CAMS) BCI

Motor imagery (MI)-based Brain-Computer Interfaces (BCIs) have shown promise in engaging the motor cortex for recovery. However, individual responses to MI-based BCIs are highly variable and relatively weak. Conversely, combined action observation (AO) and motor imagery (MI) paradigms have demonstrated stronger responses compared to AO or MI alone, along with enhanced cortical excitability. In this study, a novel BCI called Combined AO, MI, and Steady-State Motion Visual Evoked Potential (SSMVEP) (CAMS) was proposed. CAMS was designed based on gait observation and imagination. Twenty-five healthy volunteers participated in the study with CAMS serving as the intervention and SSMVEP checkerboard as the control condition. We hypothesized the CAMS intervention can induce observable increases in the negativity of the movement-related cortical potential (MRCP) associated with ankle dorsiflexion. MRCP components, including Bereitschaftspotential, were measured pre- and post-intervention. Additionally, the signal characteristics of the visual and motor responses were quantified. Finally, a two-class visual BCI classification performance was assessed. A consistent increase in negativity was observed across all MRCP components in signals over the primary motor cortex, compared to the control condition. CAMS visual BCI achieved a median accuracy of 83.8%. These findings demonstrate the ability of CAMS BCI to enhance cortical excitability in relation to movement preparation and execution. The CAMS stimulus not only evokes SSMVEP-like activity and sensorimotor rhythm but also enhances the MRCP. These findings contribute to the understanding of CAMS paradigm in enhancing cortical excitability, consistent and reliable classification performance holding promise for motor rehabilitation outcomes and future BCI design considerations.

Virtual Reality Enhanced Exercise Training in Upper Limb Function of Patients With Stroke: Meta-Analytic Study

BACKGROUND

Recovery of upper limb function after stroke secondary to ischemia or hemorrhage is crucial for patients' independence in daily living and quality of life. Virtual reality (VR) is a promising computer-based technology designed to enhance the effects of rehabilitation; however, the results of VR-based interventions remain equivocal.

OBJECTIVE

This study aims to review the plausible factors that may have influenced VR's therapeutic effects on improving upper limb function in patients with stroke, with the goal of synthesizing an optimal VR intervention protocol.

METHODS

The databases PubMed, EMBASE, Web of Science, and Cochrane Library were queried for English-language papers published from May 2022 onward. Two reviewers independently extracted data from the included papers, and discrepancies in their findings were resolved through consensus during joint meetings. The risk of bias was assessed using the Physiotherapy Evidence Database Scale and the Methodological Index for Non-Randomized Studies. Outcome variables included the Action Research Arm Test, Box-Block Test, Functional Independence Measure, Upper Extremity Fugl-Meyer Assessment, and Wolf Motor Function Test. The plausible factors examined were age, total dosage (hours), trial length (weeks), session duration (hours/session), frequency (sessions/week), and VR content design. The Bonferroni adjustment was applied to P values to prevent data from being incorrectly deemed statistically significant.

RESULTS

The final sample included 15 articles with a total of 1243 participants (age range 48.6-75.59 years). Participants in the VR therapy (VRT) group (n=455) demonstrated significantly greater improvements in upper limb function and independence in activities of daily living compared with those in the conventional therapy group (n=301). Significant factors contributing to improved outcomes in upper limb function were younger age (mean difference [MD] 5.34, 95% CI 2.18-8.5, P<.001; I2=0%), interventions lasting more than 15 hours (MD 9.67, 95% CI 4.19-15.15, P<.001; I2=0%), trial lengths exceeding 4 weeks (MD 4.02, 95% CI 1.39-6.65, P=.003; I2=15%), and more than 4 sessions per week (MD 3.48, 95% CI 0.87-6.09, P=.009; I2=0%). However, the design of the VR content, including factors such as the number of features (eg, offering exercise and functional tasks; individualized goals; activity quantification; consideration of comorbidities and baseline activity level; addressing patient needs; aligning with patient background such as education level; patient-directed goals and interests; goal setting; progressive difficulty levels; and promoting self-efficacy), did not demonstrate significant effects (MD 3.89, 95% CI -6.40 to 1.09; effect Z=1.36, P=.16).

CONCLUSIONS

Greater VR effects on improving upper limb function in patients with stroke were associated with higher training doses (exceeding 15 hours) delivered over 4-6 weeks, with shorter sessions (approximately 1 hour) scheduled 4 or more times per week. Additionally, younger patients appeared to benefit more from the VR protocol compared with older patients.

The effects of mirror therapy with neuromuscular electrical stimulation on motor and sensory functions in patients with common peroneal nerve injury

Background

Injuries to the common peroneal nerve often result in significant sensory and motor function loss, severely affecting patients' quality of life. Although existing treatments, including medication and surgery, provide some degree of efficacy, their effectiveness is limited by factors such as tolerance and adverse side effects.

Methods

This study aims to evaluate the effects of a 4-week regimen of mirror therapy combined with neuromuscular electrical stimulation on lower limb function, muscle strength, and sensation in patients with common peroneal nerve injuries. The objective is to identify novel therapeutic strategies for lower limb peripheral nerve injuries.30 patients with Common peroneal nerve caused by pelvic fractures were selected from the Rehabilitation Medicine Department of Tianjin Hospital between July 2023 and July 2024. They were randomly divided into two groups: the neuromuscular electrical stimulation group (n = 15) and the mirror therapy with neuromuscular electrical stimulation group (n = 15).

Results

After 4 weeks, it was found that mirror therapy with neuromuscular electrical stimulation has a significantly better therapeutic effect on Common peroneal nerve than simple electrical stimulation therapy, particularly in terms of superficial sensation, nerve conduction velocity and ROM.

Heart Rate Variability as a Possible Biomarker of Cognitive-Motor Integration in Post-Stroke Patients

Heart Rate Variability (HRV) refers to variation in time intervals between consecutive heartbeats, indicating autonomic nervous system's control over the heart. Time and frequency analysis of HRV could serve as predictors for severity and functional outcome in stroke. Aim of this study is to verify if HRV, measured during cognitive and sensorimotor upper limb (UL) tasks, can be used as a biomarker of cognitive-motor interaction in post-stroke patients. Forty-six patients with unilateral brain injury following stroke were enrolled: 27 (58.7%) ischemic, 19 hemorrhagic, 24 (52.2%) subacute (<6 months), and 22 chronic. Mean age at evaluation was 61 years. Right side was affected in 16 subjects (34.8%). Each patient underwent HRV recording in the following conditions: (1) Rest (5 minutes); (2) Visuomotor simulation training of the affected upper limb (UL) using Dessintey IVS3 (DE, 5 minutes); (3) Motor Imagery of the affected UL (MI, 5 minutes). UL functional outcome measures were collected for both affected and less affected sides. All patients showed reduced HRV in time and frequency domains and sympathetic tone predominance at rest. During DE and MI, a significant reduction in time domain was observed. In frequency domains, low frequency decreases during DE, with parasympathetic tone predominance. In the subgroup analyses for lesion side, only right hemiparetic patients showed parasympathetic predominance during mental tasks of the upper limb (DE and MI. No correlation was found between HRV parameters and UL functional scales. Different HRV response in time and frequency domains to mental task was observed between right and left hemiparetic subjects. This could be explained by different anatomical-functional substrates between right and left hemisphere and could reflect different behaviors during UL cognitive-motor tasks. HRV parameters were not correlated with clinical functional assessment scales, likely meaning that they possible exploring different domains.

The Role of Mirror Therapy in the Rehabilitation of the Upper Limb's Motor Deficits After Stroke: Narrative Review

Stroke is one of the leading causes of death and disability worldwide and poses a tremendous socioeconomic burden upon individuals, countries and healthcare systems. It causes debilitating symptoms and thus interferes with many aspects of the patient's life, including physical functioning, cognition, emotional status, activities of daily living, social reintegration and quality of life. Post-stroke patients frequently experience functional motor disabilities of the upper limb, which restrict autonomy and self-efficacy and cause limitations in engagement with activities and social participation, as well as difficulties in performing important occupations. It is therefore not surprising that motor impairment or loss of motor function of the upper limb is one of the most devastating sequelae of stroke. On these grounds, achieving optimal functioning of the upper limb after stroke remains a fundamental goal of stroke rehabilitation. Mirror therapy (MT) represents one of the several rehabilitation techniques used for restoring the upper limb's motor function after a stroke. However, conflicting results about the role of MT in the rehabilitation of the upper limb's motor deficits have been reported in the literature. Accordingly, the aim of this narrative review is to summarize existing evidence regarding the effects of MT on the upper limb's motor function in post-stroke patients and to further explore its role when applied in different phases of stroke.

Motor and parietal cortex activity responses to mirror visual feedback in patients with subacute stroke: An EEG study

Objective

To elucidate the immediate electrophysiological effects of mirror visual feedback (MVF) combined with or without touch task in subacute stroke.

Methods

Subacute stroke patients and healthy controls were recruited to participate in four grasping tasks (MVF or no MVF, combined with rubber ball or no ball) under electroencephalogram (EEG) monitoring. Event-related desynchronization (ERD) /event-related synchronization (ERS) and the lateralization index (LI) were utilized to observe the electrophysiological effects.

Results

MVF reduced ERD suppression in the contralateral primary motor cortex (M1) of stroke patients. This reduction was observed in the low mu band for the contralateral parietal cortex during pure MVF. The laterality effects in the low mu band under MVF was noted in M1 for stroke patients and in the parietal cortex for all participants.

Conclusions

MVF inhibits the excitability of the contralateral M1 for subacute stroke. MVF inhibit activities in the contralateral M1 and parietal cortex, and reestablished hemispheric balance in the low mu band.

Significance

MVF has an instantaneous effect on subacute stroke by inhibiting the excitability of the contralateral sensorimotor cortex. The attenuated ERD in the low mu band in contralateral M1 and parietal cortex may serve as biomarkers of MVF for stroke rehabilitation.

Effects of mirror therapy with electrical stimulation for upper limb recovery in people with stroke: a systematic review and meta-analysis

PURPOSE

To provide updated evidence about the effects of MT with ES for recovering upper extremities motor function in people with stroke.

METHODS

Systematic review and meta-analysis were completed. Methodological quality was assessed using the version 2 of the Cochrane risk-of-bias tool. The GRADE approach was employed to assess the certainty of evidence.

RESULTS

A total of 16 trials with 773 participants were included in this review. The results demonstrated that MT with ES was more effective than sham (standardized mean difference [SMD], 1.89 [1.52-2.26]) and ES alone (SMD, 0.42 [0.11-0.73]) with low quality of evidence, or MT alone (SMD, 0.47[0.04-0.89]) with low quality of evidence for improving upper extremity motor control assessed using Fugl-Meyer Assessment. MT with ES had significant improvement of (MD, 6.47 [1.92-11.01]) the upper extremity gross gripping function assessed using the Action Research Arm Test compared with MT alone with low quality of evidence. MT combined with ES was more effective than sham group (SMD, 1.17 [0.42-1.93) for improving the ability to perform activities of daily living with low quality of evidence assessed using Motor Activity Log.

CONCLUSION

MT with ES may be effective in improving upper limb motor recovery in people with stroke.

Microstate analysis reveals the temporal alignment of mirroring and mentalizing systems

The aim of the study is to understand how Mirror Neuron System (MNS) and Mentalizing Network (MZN) interact with each other. EEG data was collected during a photo judgment task with pictures of actions or facial expressions. Participants (N = 30, 63% women) were asked to either identify how the shown action/expression was being performed (MNS) or what the goal or intention behind the action was (MZN). Data were analyzed using microstate analysis, source localization and Event-Related Potentials. When comparing the action types, we found early divergence between the brain states of MNS and MZN when comparing the same action type. There was temporal alignment between the start and end time of the induced microstates, among the same action type. Between different action types, the timing was slightly shifted. Temporally, there was a greater overlap between the timing of the states between networks within the same action type as compared to within networks across action types. The MNS and MZN are acting in parallel rather then subsequently and possibly feed into each other. Furthermore, the MNS and MZN do not specifically react to one action type over the other, but their activity is influenced by the action type.

Attentional state-synchronous peripheral electrical stimulation during action observation induced distinct modulation of corticospinal plasticity after stroke

Introduction

Brain computer interface-based action observation (BCI-AO) is a promising technique in detecting the user's cortical state of visual attention and providing feedback to assist rehabilitation. Peripheral nerve electrical stimulation (PES) is a conventional method used to enhance outcomes in upper extremity function by increasing activation in the motor cortex. In this study, we examined the effects of different pairings of peripheral nerve electrical stimulation (PES) during BCI-AO tasks and their impact on corticospinal plasticity.

Materials and methods

Our innovative BCI-AO interventions decoded user's attentive watching during task completion. This process involved providing rewarding visual cues while simultaneously activating afferent pathways through PES. Fifteen stroke patients were included in the analysis. All patients underwent a 15 min BCI-AO program under four different experimental conditions: BCI-AO without PES, BCI-AO with continuous PES, BCI-AO with triggered PES, and BCI-AO with reverse PES application. PES was applied at the ulnar nerve of the wrist at an intensity equivalent to 120% of the sensory threshold and a frequency of 50 Hz. The experiment was conducted randomly at least 3 days apart. To assess corticospinal and peripheral nerve excitability, we compared pre and post-task (post 0, post 20 min) parameters of motor evoked potential and F waves under the four conditions in the muscle of the affected hand.

Results

The findings indicated that corticospinal excitability in the affected hemisphere was higher when PES was synchronously applied with AO training, using BCI during a state of attentive watching. In contrast, there was no effect on corticospinal activation when PES was applied continuously or in the reverse manner. This paradigm promoted corticospinal plasticity for up to 20 min after task completion. Importantly, the effect was more evident in patients over 65 years of age.

Conclusion

The results showed that task-driven corticospinal plasticity was higher when PES was applied synchronously with a highly attentive brain state during the action observation task, compared to continuous or asynchronous application. This study provides insight into how optimized BCI technologies dependent on brain state used in conjunction with other rehabilitation training could enhance treatment-induced neural plasticity.

Evidence of mirror therapy for recruitment of ipsilateral motor pathways in stroke recovery: A resting fMRI study

Mirror therapy (MT) has been proposed to promote motor recovery post-stroke through activation of mirror neuron system, recruitment of ipsilateral motor pathways, or/and increasing attention toward the affected limb. However, neuroimaging evidence for these mechanisms is still lacking. To uncover the underlying mechanisms, we designed a randomized controlled study and used a voxel-based whole-brain analysis of resting-state fMRI to explore the brain reorganizations induced by MT. Thirty-five stroke patients were randomized to an MT group (n ​= ​16) and a conventional therapy (CT) group (n ​= ​19) for a 4-week intervention. Before and after the intervention, the Fugl-Meyer Assessment Upper Limb subscale (FMA-UL) and resting-state fMRI were collected. A healthy cohort (n ​= ​16) was established for fMRI comparison. The changes in fractional amplitude of low-frequency fluctuation (fALFF) and seed-based functional connectivity were analyzed to investigate the impact of intervention. Results showed that greater FMA-UL improvement in the MT group was associated with the compensatory increase of fALFF in the contralesional precentral gyrus (M1) region and the re-establishment of functional connectivity between the bilateral M1 regions, which facilitate motor signals transmission via the ipsilateral motor pathways from the ipsilesional M1, contralesional M1, to the affected limb. A step-wise linear regression model revealed these two brain reorganization patterns collaboratively contributed to FMA-UL improvement. In conclusion, MT achieved motor rehabilitation primarily by recruitment of the ipsilateral motor pathways. Trial Registration Information: http://www.chictr.org.cn. Unique Identifier. ChiCTR-INR-17013644, submitted on December 2, 2017.

[Possibilities of mirror therapy in cognitive rehabilitation after stroke]

The review provides a brief overview of the history of the development of mirror therapy. Current data on the putative mechanisms of mirror therapy as well as the theory of mirror neurons are presented. The authors describe the implementation of the effects of mirror therapy in motor rehabilitation after stroke, including motor imagination or mental simulation of actions, strengthening of spatial attention and self-perception, activation of the ipsilateral corticospinal tract, reorganization of neuronal networks that influence the state of structurally intact but functionally inactive neurons. The authors reflected the prerequisites for the use of mirror therapy in the rehabilitation of cognitive impairment in poststroke patients. The results of current clinical studies and case reports of the use of mirror therapy for the rehabilitation of speech and non-speech cognitive disorders, and neglect syndrome after stroke are presented.

Effects of mirror therapy on spasticity and sensory impairment after stroke: Systematic review and meta-analysis

OBJECTIVE

To review and synthesize existing evidence on the effectiveness of mirror therapy (MT) compared to active exercise-based interventions (ie, cross-training and conventional exercise) for reducing spasticity and sensory impairment in stroke survivors. TYPE: Systematic Review and Metanalysis.

LITERATURE SURVEY

Pubmed/MEDLINE, Cochrane, Embase, CINAHL, and Physiotherapy Evidence Database (PEDro), were searched.

METHODOLOGY

Randomized controlled trials (RCTs) that investigated MT effectiveness in improving spasticity and sensory impairment in stroke survivors compared to a control group.

SYNTHESIS

Fifteen RCTs (653 volunteers) were included. Spasticity improvements achieved with MT were similar to those obtained with cross-training (standard mean difference [SMD]: 0.12, 95% confidence interval [CI]: -0.43 to 0.68). In addition, when further combined with conventional exercise, spasticity improved similarly in both groups (SMD: 0.10, 95% CI: -0.16, 0.36). Lastly, when MT plus exercise was compared to exercise alone, spasticity decreased in both groups (SMD: 0.16, 95% CI: -0.16 to 0.48). Nevertheless, none of the Interventions seem effective on sensory impairment (SMD: 0.27, 95% CI: -0.28 to 0.81).

CONCLUSIONS

MT is equally effective as other exercise therapies, such as cross-training and conventional exercise, for improving spasticity in stroke survivors, whereas none of the explored interventions yielded beneficial effects on sensory impairment. Further well-designed RCTs are needed to confirm the results.

The effect of combining action observation in virtual reality with kinesthetic motor imagery on cortical activity

Introduction

In the past, various techniques have been used to improve motor imagery (MI), such as immersive virtual-reality (VR) and kinesthetic rehearsal. While electroencephalography (EEG) has been used to study the differences in brain activity between VR-based action observation and kinesthetic motor imagery (KMI), there has been no investigation into their combined effect. Prior research has demonstrated that VR-based action observation can enhance MI by providing both visual information and embodiment, which is the perception of oneself as part of the observed entity. Additionally, KMI has been found to produce similar brain activity to physically performing a task. Therefore, we hypothesized that utilizing VR to offer an immersive visual scenario for action observation while participants performed kinesthetic motor imagery would significantly improve cortical activity related to MI.

Methods

In this study, 15 participants (9 male, 6 female) performed kinesthetic motor imagery of three hand tasks (drinking, wrist flexion-extension, and grabbing) both with and without VR-based action observation.

Results

Our results indicate that combining VR-based action observation with KMI enhances brain rhythmic patterns and provides better task differentiation compared to KMI without action observation.

Discussion

These findings suggest that using VR-based action observation alongside kinesthetic motor imagery can improve motor imagery performance.

Conventional Mirror Therapy versus Immersive Virtual Reality Mirror Therapy: The Perceived Usability after Stroke

Background

Stroke is a widespread and complex health issue, with many survivors requiring long-term rehabilitation due to upper-limb impairment. This study is aimed at comparing the perceived usability of two feedback-based stroke therapies: conventional mirror therapy (MT) and immersive virtual reality mirror therapy (VR).

Methods

The study involved 45 participants, divided into three groups: the stroke survivors (n = 15), stroke-free older adults (n = 15), and young controls (n = 15). Participants performed two tasks using both MT and VR in a semirandom sequence. Usability instruments (SUS and NASA-TLX) were applied at the end of the activities, along with two experience-related questions.

Results

The results indicated that both MT and VR had similar levels of perceived usability, with MT being more adaptable and causing less overall discomfort. Conversely, VR increased the perception of task difficulty and prevented participants from diverting their attention from the mirror-based feedback.

Conclusion

While VR was found to be less comfortable than MT, both systems exhibited similar perceived usability. The comfort levels of the goggles may play a crucial role in determining the usability of VR for upper limb rehabilitation after stroke.

Enhancing upper-limb neurorehabilitation in chronic stroke survivors using combined action observation and motor imagery therapy

Introduction

For people who have had a stroke, recovering upper-limb function is a barrier to independence. When movement is difficult, mental practice can be used to complement physical therapy. In this within-participants study we investigated the effects of combined action observation and motor imagery (AO + MI) therapy on upper-limb recovery in chronic stroke survivors.

Methods

A Graeco-Latin Square design was used to counterbalance four mental practice conditions (AO + MI, AO, MI, Control) across four cup-stacking tasks of increasing complexity. Once a week, for five consecutive weeks, participants (n = 10) performed 16 mental practice trials under each condition. Each trial displayed a 1st person perspective of a cup-stacking task performed by an experienced model. For AO, participants watched each video and responded to an occasional color cue. For MI, participants imagined the effort and sensation of performing the action; cued by a series of still-images. For combined AO + MI, participants observed a video of the action while they simultaneously imagined performing the same action in real-time. At three time points (baseline; post-test; two-week retention test) participants physically executed the three mentally practiced cup-stacking tasks, plus a fourth unpractised sequence (Control), as quickly and accurately as possible.

Results

Mean movement execution times were significantly reduced overall in the post-test and the retention test compared to baseline. At retention, movement execution times were significantly shorter for combined AO + MI compared to both MI and the Control. Individual participants reported clinically important changes in quality of life (Stroke Impact Scale) and positive qualitative experiences of AO + MI (social validation).

Discussion

These results indicate that when physical practice is unsuitable, combined AO + MI therapy could offer an effective adjunct for neurorehabilitation in chronic stroke survivors.

Action Observation Therapy for Arm Recovery after Stroke: A Preliminary Investigation on a Novel Protocol with EEG Monitoring

This preliminary study introduces a novel action observation therapy (AOT) protocol associated with electroencephalographic (EEG) monitoring to be used in the future as a rehabilitation strategy for the upper limb in patients with subacute stroke. To provide initial evidence on the usefulness of this method, we compared the outcome of 11 patients who received daily AOT for three weeks with that of patients who undertook two other approaches recently investigated by our group, namely intensive conventional therapy (ICT), and robot-assisted therapy combined with functional electrical stimulation (RAT-FES). The three rehabilitative interventions showed similar arm motor recovery as indexed by Fugl-Meyer's assessment of the upper extremity (FMA_UE) and box and block test (BBT). The improvement in the FMA_UE was yet more favourable in patients with mild/moderate motor impairments who received AOT, in contrast with patients carrying similar disabilities who received the other two treatments. This suggests that AOT might be more effective in this subgroup of patients, perhaps because the integrity of their mirror neurons system (MNS) was more preserved, as indexed by EEG recording from central electrodes during action observation. In conclusion, AOT may reveal an effective rehabilitative tool in patients with subacute stroke; the EEG evaluation of MNS integrity may help to select patients who could maximally benefit from this intervention.

Continual Learning of a Transformer-Based Deep Learning Classifier Using an Initial Model from Action Observation EEG Data to Online Motor Imagery Classification

The motor imagery (MI)-based brain computer interface (BCI) is an intuitive interface that enables users to communicate with external environments through their minds. However, current MI-BCI systems ask naïve subjects to perform unfamiliar MI tasks with simple textual instruction or a visual/auditory cue. The unclear instruction for MI execution not only results in large inter-subject variability in the measured EEG patterns but also causes the difficulty of grouping cross-subject data for big-data training. In this study, we designed an BCI training method in a virtual reality (VR) environment. Subjects wore a head-mounted device (HMD) and executed action observation (AO) concurrently with MI (i.e., AO + MI) in VR environments. EEG signals recorded in AO + MI task were used to train an initial model, and the initial model was continually improved by the provision of EEG data in the following BCI training sessions. We recruited five healthy subjects, and each subject was requested to participate in three kinds of tasks, including an AO + MI task, an MI task, and the task of MI with visual feedback (MI-FB) three times. This study adopted a transformer- based spatial-temporal network (TSTN) to decode the user's MI intentions. In contrast to other convolutional neural network (CNN) or recurrent neural network (RNN) approaches, the TSTN extracts spatial and temporal features, and applies attention mechanisms along spatial and temporal dimensions to perceive the global dependencies. The mean detection accuracies of TSTN were 0.63, 0.68, 0.75, and 0.77 in the MI, first MI-FB, second MI-FB, and third MI-FB sessions, respectively. This study demonstrated the AO + MI gave an easier way for subjects to conform their imagery actions, and the BCI performance was improved with the continual learning of the MI-FB training process.

Non-invasive Brain Stimulation and Prism Adaptation in Art Constructive Errors in Painting

Introduction

This study aimed to investigate the influence of neglect and the effect of prism adaptation (PA) combined with continuous Theta-burst transcranial magnetic stimulation (cTBS) on the art constructive errors in painting rehabilitation of stroke patients with neglect.

Methods

Fourteen patients with neglect and art constructive errors in painting secondary to stroke were randomly assigned to the rehabilitation group and received PA combined with the inhibitory protocol of cTBS over the intact parietal cortex; the control group received PA combined with sham cTBS for two weeks in ten daily sessions. Patients were assessed for art constructive errors in painting in figure copying test (FCT), and coloring test (CT) before and after the intervention. Art constructive errors in painting were classified into omission, deformation, size, neglect of warm colors, and perseveration of errors. Neglect was evaluated using the line bisection task (LBT), figure copying test (FCT), and coloring test (CT).

Results

All patients showed a significant improvement in art constructive errors in painting (measured using the pattern of painting' errors in FCT and CT), and neglect (measured using LBT, FCT, and CT) (P<0.05). Omission, neglect of warm colors, and deformation were the most frequent errors.

Conclusion

Neglect and rehabilitation influence the painting system in stroke patients. Both approaches improved art constructive errors in painting and neglect symptoms.

Effects of trunk stabilization exercises using laser pointer visual feedback in patients with chronic stroke: A randomized controlled study

BACKGROUND

Many previous studies have cited the importance of trunk stabilization exercises in patients with stroke. However, the evidence for optimal trunk stabilization exercises for patients with stroke is still lacking.

OBJECTIVE

To investigate the effects of laser pointer visual feedback in trunk stabilization exercises that are important for improving trunk dysfunction in patients with stroke.

METHODS

In total, 30 patients with chronic stroke were randomly assigned to experimental and control groups. The experimental group underwent a traditional stroke rehabilitation program and trunk stabilization exercises using laser pointer visual feedback. The control group underwent a traditional stroke rehabilitation program and trunk stabilization exercises without visual feedback. Pre- and postintervention results after 6 weeks were evaluated using the Berg Balance Scale, static and dynamic plantar pressure, 10-m walk test, and the Korean version of the Fall Efficacy Scale. The results were analyzed using a general linear repeated measurement model.

RESULTS

Both groups showed significant improvements in BBS scores, static plantar pressure, dynamic plantar pressure, 10 MWT, and K-FES scores after 6 weeks of intervention (P< 0.05). Compared to the control group, significant improvements were observed in the experimental group in the Berg Balance Scale scores, dynamic paretic posterior plantar pressure, 10-m walk test, and Korean version of the Fall Efficacy Scale scores (P< 0.025).

CONCLUSION

Our results demonstrated the effectiveness of visual feedback during trunk stabilization exercises for resolving trunk dysfunction in patients with stroke. Trunk stabilization exercises using laser pointer visual feedback have been found to be more effective in balance, walking, and fall efficacy in patients with stroke.

The Effect of Mirror Visual Feedback on Spatial Neglect for Patients after Stroke: A Preliminary Randomized Controlled Trial

We investigated the effects of mirror visual feedback (MVF), with reference to using a glass wall or a covered mirror, on the reduction of spatial neglect for patients with stroke. A total of 21 subacute patients with left spatial neglect after right-hemispheric stroke were randomly assigned to 3 groups: MVF, sham 1 (viewing the hemiparetic arm through the transparent glass during bilateral arm movement) and sham 2 (using a covered mirror). The 3-week treatment program for all groups consisted of 12 sessions of movement tasks for the hemiparetic arm graded according to the severity of arm impairments. Blinded assessments were administered at pre/post and a three-week follow-up. The results showed that there was no significant advantage for MVF than sham 1; however, MVF was more beneficial than sham 2, as shown by the line crossing (p = 0.022). Improvement in discriminating the left-gap figures on the left and right side of the page in the Gap Detection Test was greater in MVF than using the covered mirror (p = 0.013; p = 0.010), showing a slight advantage of MVF in alleviating allocentric symptoms. Our study confirms that MVF was superior to using a covered mirror as a method for reducing spatial neglect and in alleviating its allocentric symptoms, but no significant advantage over bilateral arm movement through transparent glass was found. Further research in comparing their therapeutic effects is warranted.

Effects of Meaningful Action Observation Therapy on Occupational Performance, Upper Limb Function, and Corticospinal Excitability Poststroke: A Double-Blind Randomized Control Trial

Introduction

Action observation therapy (AOT) is a mirror neuron-based approach that has been recently used in poststroke rehabilitation. The main goal of this study was to investigate the effectiveness of AOT of occupations and tasks that are meaningful for chronic stroke patients on occupational performance, upper-extremity function, and corticospinal changes.

Method

A randomized control trial was designed to compare between experimental (n = 13) and control groups (n = 14). In both groups, the execution of meaningful tasks was practiced, but the videos of those tasks were just shown to the experiment group. Instead, patients in the control group watched nature videos as a placebo. Clinical outcomes were evaluated using the Canadian Occupational Performance Measure (COPM), Fugl-Meyer Assessment (FMA), Action Research Arm Test (ARAT), and Box-Block Test (BBT) on 3 occasions: baseline, post (at 4 weeks), and follow-up (at 8 weeks). The assessments of central motor conduction time (CMCT) for abductor policis brevis (APB) and extensor indicis (EI) were only recorded at baseline and posttreatment. Both assessors of clinical and neurophysiological outcomes were blinded to the allocation of subjects.

Result

Finally, the results of outcomes in 24 patients who completed the study were analyzed. In both groups, significant improvements after treatment were seen for most outcomes (p ≤ 0.05). These changes were persistent until follow-up. There were significant differences in COPM performance (p = 0.03) and satisfaction (p = 0.001) between the experimental and control groups. In contrast, other clinical assessments such as FMA, ARAT, and BBT did not show significant differences between the two treatments (p ≥ 0.05). The results of CMCT related to APB showed a more significant change in the experiment group compared to the control group (p = 0.022). There was no difference in change detected between the two groups for CMCT related to EI after treatments.

Conclusion

Observation and execution of meaningful activities can enhance the effects of simply practicing those activities on occupational performance/satisfaction and corticospinal excitability poststroke.

Examining the effectiveness of virtual, augmented, and mixed reality (VAMR) therapy for upper limb recovery and activities of daily living in stroke patients: a systematic review and meta-analysis

INTRODUCTION

Virtual reality (VR), augmented reality (AR), and mixed reality (MR) are emerging technologies in the field of stroke rehabilitation that have the potential to overcome the limitations of conventional treatment. Enhancing upper limb (UL) function is critical in stroke impairments because the upper limb is involved in the majority of activities of daily living (ADL).

METHODS

This study reviewed the use of virtual, augmented and mixed reality (VAMR) methods for improving UL recovery and ADL, and compared the effectiveness of VAMR treatment to conventional rehabilitation therapy. The databases ScienceDirect, PubMed, IEEE Xplore, and Web of Science were examined, and 50 randomized control trials comparing VAMR treatment to standard therapy were determined. The random effect model and fixed effect model are applied based on heterogeneity.

RESULTS

The most often used outcomes of UL recovery and ADL in stroke rehabilitation were the Fugl-Meyer Assessment for Upper Extremities (FMA-UE), followed by the Box and Block Test (BBT), the Wolf Motor Function Test (WMFT), and the Functional Independence Measure (FIM). According to the meta-analysis, VR, AR, and MR all have a significant positive effect on improving FMA-UE for UL impairment (36 studies, MD = 3.91, 95 percent CI = 1.70-6.12, P = 0.0005) and FIM for ADL (10 studies, MD = 4.25, 95 percent CI = 1.47-7.03, P = 0.003), but not on BBT and WMFT for the UL function tests (16 studies, MD = 2.07, 95 percent CI = - 0.58-4.72, P = 0.13), CONCLUSIONS: VAMR therapy was superior to conventional treatment in UL impairment and daily function outcomes, but not UL function measures. Future studies might include further high-quality trials examining the effect of VR, AR, and MR on UL function measures, with an emphasis on subgroup meta-analysis by stroke type and recovery stage.

An Effective Fusing Approach by Combining Connectivity Network Pattern and Temporal-Spatial Analysis for EEG-Based BCI Rehabilitation

Motor-modality-based brain computer interface (BCI) could promote the neural rehabilitation for stroke patients. Temporal-spatial analysis was commonly used for pattern recognition in this task. This paper introduced a novel connectivity network analysis for EEG-based feature selection. The network features of connectivity pattern not only captured the spatial activities responding to motor task, but also mined the interactive pattern among these cerebral regions. Furthermore, the effective combination between temporal-spatial analysis and network analysis was evaluated for improving the performance of BCI classification (81.7%). And the results demonstrated that it could raise the classification accuracies for most of patients (6 of 7 patients). This proposed method was meaningful for developing the effective BCI training program for stroke rehabilitation.

The Reaching Phase of Feeding and Self-Care Actions Optimizes Action Observation Effects in Chronic Stroke Subjects

BACKGROUND

The Action Observation Therapy (AOT) is a well-established post-stroke rehabilitation treatment based on the theoretical framework of the Mirror Neuron System (MNS) activation. However, AOT protocols are still heterogeneous in terms of video contents of observed actions.

OBJECTIVE

The aim of this study was to analyze electroencephalographic (EEG) recordings in stroke patients during the observation of different videos of task-specific upper limb movements, and to define which category of actions can elicit a stronger cortical activation in the observer's brain.

METHODS

Signals were analyzed from 19 chronic stroke subjects observing customized videos that represented 3 different categories of upper limb actions: Finalized Actions, Non-Finalized Actions, and Control Videos. The Event-Related Desynchronization in the µ and β bands was chosen to identify the involvement of the cerebral cortex: the area of the normalized power spectral density was calculated for each category and, deepening, for the reaching and completion sub-phases of Finalized Actions. For descriptive purposes, the time course of averaged signal power was described. The Kruskal-Wallis test (P < .05) was applied.

RESULTS

The analysis showed a greater desynchronization when subjects observed Finalized Actions with respect to Non-Finalized in all recorded areas; Control videos provoked a synchronization in the same areas and frequency bands. The reaching phase of feeding and self-care actions evoked a greater suppression both in µ and β bands.

CONCLUSIONS

The observation of finalized arm movements seems to elicit the strongest activation of the MNS in chronic stroke patients. This finding may help the clinicians to design future AOT-based stroke rehabilitation protocols.

CLINICAL TRIAL REGISTRATION

Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT04047134.

Comparison of Sensory Observation and Somatosensory Stimulation in Mirror Neurons and the Sensorimotor Network: A Task-Based fMRI Study

Objective

This study aimed to investigate brain plasticity by somatosensory stimulation (SS) and sensory observation (SO) based on mirror neuron and embodied cognition theory. Action observation therapy has been widely adopted for motor function improvement in post-stroke patients. However, it is uncertain whether the SO approach can also contribute to the recovery of sensorimotor function after stroke. In this study, we explored the therapeutic potential of SO for sensorimotor dysfunction and provided new evidence for neurorehabilitation.

Methods

Twenty-six healthy right-handed adults (12 men and 14 women), aged 18–27 (mean, 22.12; SD, 2.12) years were included. All subjects were evaluated with task-based functional magnetic resonance imaging (fMRI) to discover the characteristics and differences in brain activation between SO and SS. We adopted a block design with two conditions during fMRI scanning: observing a sensory video of brushing (task condition A, defined as SO) and brushing subjects' right forearms while they watched a nonsense string (task condition B, defined as SS). One-sample t-tests were performed to identify brain regions and voxels activated for each task condition. A paired-sample t-test and conjunction analysis were performed to explore the differences and similarities between SO and SS.

Results

The task-based fMRI showed that the bilateral postcentral gyrus, left precentral gyrus, bilateral middle temporal gyrus, right supramarginal gyrus, and left supplementary motor area were significantly activated during SO or SS. In addition to these brain regions, SO could also activate areas containing mirror neurons, like the left inferior parietal gyrus.

Conclusion

SO could activate mirror neurons and sensorimotor network-related brain regions in healthy subjects like SS. Therefore, SO may be a promising novel therapeutic approach for sensorimotor dysfunction recovery in post-stroke patients.

Use of recognition of laterality through implicit motor imagery for the improvement of postural control and balance in subacute stroke patients: a randomized controlled study

INTRODUCTION

Motor Imagery techniques may be used as a complement to the recovery of motor sequelae after a stroke, as during the evocation of a movement the activation of neuronal circuits involved in the actual execution of the movement occurs.

PATIENTS AND METHODS

A simple-blind randomized controlled trial was conducted. A total of 38 patients were randomly assigned to a study group. Both groups performed, for four weeks, five weekly sessions of neurorehabilitation and three weekly sessions of experimental or control intervention, respectively.The experimental group training the recognition of laterality, while the control group the recognition of body parts. Participants were evaluated pre and post intervention with posturography parameters -Sway area (AREA), Sway path length (LONG), difference in weigthload between lower limbs (DIFLOAD)-, the Berg Balance scale (BBS), the Barthel Index (BI), the Time Up and Go Test (TUG), the Functional Ambulation Categories (FAC), and the quality-of-life scale for stroke (ECVI-38).

RESULTS

After performing the intragroup analysis, statistical significance was obtained for AREA (p < 0.001), LONG (p = 0.04), DIFLOAD (p = 0.02), BBS (p < 0.001), BI (p < 0.001), FAC (p < 0.001), and ECVI-38 (p < 0.001) in the experimental group; and for DIFLOAD (p = 0.01), BBS (p = 0.001), BI (p = 0.001), TUG (p = 0.04), FAC (p = 0.03), and ECVI-38 (p = 0.003) in the control group. In the intergroup analysis, statistical significance was obtained for AREA (p = 0.03), BBS (p = 0.03), FAC (p = 0.02) and ECVI-38 (p = 0.002) at postintervention time.

CONCLUSIONS

Combined use of physical rehabilitation and recognition of laterality through implicit motor imagery tasks, improves balance and functions related to postural control in subacute stroke patients.

Brain Function and Upper Limb Deficit in Stroke With Motor Execution and Imagery: A Cross-Sectional Functional Magnetic Resonance Imaging Study

Background

Motor imagery training might be helpful in stroke rehabilitation. This study explored if a specific modulation of movement-related regions is related to motor imagery (MI) ability.

Methods

Twenty-three patients with subcortical stroke and 21 age-matched controls were recruited. They were subjectively screened using the Kinesthetic and Visual Imagery Questionnaire (KVIQ). They then underwent functional magnetic resonance imaging (fMRI) while performing three repetitions of different motor tasks (motor execution and MI). Two separate runs were acquired [motor execution tasks (ME and rest) and motor imagery (MI and rest)] in a block design. For the different tasks, analyses of cerebral activation and the correlation of motor/imagery task-related activity and KVIQ scores were performed.

Results

During unaffected hand (UH) active grasp movement, we observed decreased activations in the contralateral precentral gyrus (PreCG), contralateral postcentral gyrus (PoCG) [p &lt; 0.05, family wise error (FWE) corrected] and a positive correlation with the ability of FMA-UE (PreCG: r = 0.46, p = 0.028; PoCG: r = 0.44, p = 0.040). During active grasp of the affected hand (AH), decreased activation in the contralateral PoCG was observed (p &lt; 0.05, FWE corrected). MI of the UH induced significant activations of the contralateral superior frontal gyrus, opercular region of the inferior frontal gyrus, and ipsilateral ACC and deactivation in the ipsilateral supplementary motor area (p &lt; 0.05, AlphaSim correction). Ipsilateral anterior cingulate cortex (ACC) activity negatively correlated with MI ability (r = =–0.49, p = 0.022). Moreover, we found significant activation of the contralesional middle frontal gyrus (MFG) during MI of the AH.

Conclusion

Our results proved the dominant effects of MI dysfunction that exist in stroke during the processing of motor execution. In the motor execution task, the enhancement of the contralateral PreCG and PoCG contributed to reversing the motor dysfunction, while in the MI task, inhibition of the contralateral ACC can increase the impaired KVIQ ability. The bimodal balance recovery model can explain our results well. Recognizing neural mechanisms is critical to helping us formulate precise strategies when intervening with electrical or magnetic stimulation.

Effects of a Virtual Reality-Based Mirror Therapy Program on Improving Sensorimotor Function of Hands in Chronic Stroke Patients: A Randomized Controlled Trial

Background. Embedding mirror therapy within a virtual reality (VR) system may have a superior effect on motor remediation for chronic stroke patients. Objective. The objective is to investigate the differences in the effects of using conventional occupational therapy (COT), mirror therapy (MT), and VR-based MT (VR-MT) training on the sensorimotor function of the upper limb in chronic stroke patients. Methods. This was a single-blinded randomized controlled trial. A total of 54 participants, including chronic stroke patients, were randomized into a COT, MT, or VR-MT group. In addition to 20-minute sessions of task-specific training, patients received programs of 30 minutes of VR-MT, 30 minutes of MT, and 30 minutes of COT, respectively, in the VR-MT, MT, and COT groups twice a week for 9 weeks. The Fugl-Meyer motor assessment for the upper extremities (FM-UE; primary outcome), Semmes-Weinstein monofilament, motor activity log, modified Ashworth scale, and the box and block test were recorded at pre-treatment, post-intervention, and 12-week follow-up. Results. Fifty-two participants completed the study. There was no statistically significant group-by-time interaction effects on the FM-UE score (generalized estimating equations, (GEE), P = .075). Meanwhile, there were statistically significant group-by-time interaction effects on the wrist sub-score of the FM-UE (GEE, P = .012) and the result of box and block test (GEE, P = .044). Conclusions. VR-MT seemed to have potential effects on restoring the upper extremity motor function for chronic stroke patients. However, further confirmatory studies are warranted for the rather weak evidence of adding VR to MT on improving primary outcome of this study. Clinical trial registration: NCT03329417.

The Effects of Action Observation Therapy as a Rehabilitation Tool in Parkinson’s Disease Patients: A Systematic Review

During Action Observation (AO), patients observe human movements that they then try to imitate physically. Until now, few studies have investigated the effectiveness of it in Parkinson’s disease (PD). However, due to the diversity of interventions, it is unclear how the dose and characteristics can affect its efficiency. We investigated the AO protocols used in PD, by discussing the intervention features and the outcome measures in relation to their efficacy. A search was conducted through MEDLINE, Scopus, Cochrane, and WoS until November 2021, for RCTs with AO interventions. Participant’s characteristics, treatment features, outcome measures, and main results were extracted from each study. Results were gathered into a quantitative synthesis (MD and 95% CI) for each time point. Seven studies were included in the review, with 227 participants and a mean PEDro score of 6.7. These studies reported positive effects of AO in PD patients, mainly on walking ability and typical motor signs of PD like freezing of gait. However, disagreements among authors exist, mainly due to the heterogeneity of the intervention features. In overall, AO improves functional abilities and motor control in PD patients, with the intervention dose and the characteristics of the stimulus playing a decisive role in its efficacy.

Motor Imagery and Action Observation as Appropriate Strategies for Home-Based Rehabilitation: A Mini-Review Focusing on Improving Physical Function in Orthopedic Patients

Dynamic stability of the knee and weakness of the extensor muscles are considered to be the most important functional limitations after anterior cruciate ligament (ACL) injury, probably due to changes at the central (cortical and corticospinal) level of motor control rather than at the peripheral level. Despite general technological advances, fewer contraindicative surgical procedures, and extensive postoperative rehabilitation, up to 65% of patients fail to return to their preinjury level of sports, and only half were able to return to competitive sport. Later, it becomes clear that current rehabilitation after knee surgery is not sufficient to address the functional limitations after ACL reconstruction even years after surgery. Therefore, new therapeutic tools targeting the central neural system, i.e., the higher centers of motor control, should be investigated and integrated into current rehabilitation practice. To improve motor performance when overt movement cannot be fully performed (e.g., due to pain, impaired motor control, and/or joint immobilization), several techniques have been developed to increase physical and mental activation without the need to perform overt movements. Among the most popular cognitive techniques used to increase physical performance are motor imagery and action observation practices. This review, which examines the available evidence, presents the underlying mechanisms of the efficacy of cognitive interventions and provides guidelines for their use at home.

Synergistic Immediate Cortical Activation on Mirror Visual Feedback Combined With a Soft Robotic Bilateral Hand Rehabilitation System: A Functional Near Infrared Spectroscopy Study

Background

Mirror visual feedback (MVF) has been widely used in neurological rehabilitation. Due to the potential gain effect of the MVF combination therapy, the related mechanisms still need be further analyzed.

Methods

Our self-controlled study recruited 20 healthy subjects (age 22.150 ± 2.661 years) were asked to perform four different visual feedback tasks with simultaneous functional near infrared spectroscopy (fNIRS) monitoring. The right hand of the subjects was set as the active hand (performing active movement), and the left hand was set as the observation hand (static or performing passive movement under soft robotic bilateral hand rehabilitation system). The four VF tasks were designed as RVF Task (real visual feedback task), MVF task (mirror visual feedback task), BRM task (bilateral robotic movement task), and MVF + BRM task (Mirror visual feedback combined with bilateral robotic movement task).

Results

The beta value of the right pre-motor cortex (PMC) of MVF task was significantly higher than the RVF task (RVF task: -0.015 ± 0.029, MVF task: 0.011 ± 0.033, P = 0.033). The beta value right primary sensorimotor cortex (SM1) in MVF + BRM task was significantly higher than MVF task (MVF task: 0.006 ± 0.040, MVF + BRM task: 0.037 ± 0.036, P = 0.016).

Conclusion

Our study used the synchronous fNIRS to compare the immediate hemodynamics cortical activation of four visual feedback tasks in healthy subjects. The results showed the synergistic gain effect on cortical activation from MVF combined with a soft robotic bilateral hand rehabilitation system for the first time, which could be used to guide the clinical application and the future studies.

Development and user experience of an innovative multi-mode stroke rehabilitation system for the arm and hand for patients with stroke

Many individuals with stroke experience upper-limb motor deficits, and a recent trend is to develop novel devices for enhancing their motor function. This study aimed to develop a new upper-limb rehabilitation system with the integration of two rehabilitation therapies into one system, digital mirror therapy (MT) and action observation therapy (AOT), and to test the usability of this system. In the part I study, the new system was designed to operate in multiple training modes of digital MT (i.e., unilateral and bilateral modes) and AOT (i.e., pre-recorded and self-recorded videos) with self-developed software. In the part II study, 4 certified occupational therapists and 10 stroke patients were recruited for evaluating usability. The System Usability Scale (SUS) (maximum score = 100) and a self-designed questionnaire (maximum score = 50) were used. The mean scores of the SUS were 79.38 and 80.00, and those of the self-designed questionnaire were 41.00 and 42.80, respectively, for the therapists and patients after using this system, which indicated good usability and user experiences. This novel upper-limb rehabilitation system with good usability might be further used to increase the delivery of two emerging rehabilitation therapies, digital AOT and MT, to individuals with stroke.

Mirror Therapy Rehabilitation in Stroke: A Scoping Review of Upper Limb Recovery and Brain Activities

BACKGROUND

Mirror therapy (MT) has been used as a treatment for various neurological disorders. Recent application of electroencephalogram (EEG) to the MT study allows researchers to gain insight into the changes in brain activity during the therapy.

OBJECTIVE

This scoping review is aimed at mapping existing evidence and identifying knowledge gaps about the effects of MT on upper limb recovery and its application for individuals with chronic stroke.

METHODS AND MATERIALS

A scoping review through a systematic literature search was conducted using PubMed, CINAHL, PsycINFO, and Scopus databases. Twenty articles published between 2010 and 2020 met the inclusion criteria. The efficacy of MT on upper limb recovery and brain activity during MT were discussed according to the International Classification of Functioning, Disability and Health (ICF).

RESULTS

A majority of the studies indicated positive effects of MT on upper limb recovery from the body structure/functional domain. All studies used EEG to indicate brain activation during MT.

CONCLUSION

MT is a promising intervention for improving upper limb function for individuals with chronic stroke. This review also highlights the need to incorporate EEG into the MT study to capture brain activity and understand the mechanism underlying the therapy.

Non-invasive, non-pharmacological/bio-technological interventions towards neurorestoration upshot after ischemic stroke, in adults-systematic, synthetic, literature review

Considering its marked life-threatening and (not seldom: severe and/or permanent) disabling, potential, plus the overall medico-psycho-socio-economic tough burden it represents for the affected persons, their families and the community, the cerebrovascular accident (CVA)-including with the, by far more frequent, ischemic type-is subject to considerable scientific research efforts that aim (if possible) at eliminating the stroke induced lesions, and consist, as well, in ambitious-but still poorly transferable into medical practice-goals such as brain neuroregeneration and/or repair, within related corollary/upshot of neurorestoration. We have conducted, in this respect, a systematic and synthetic literature review, following the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)" concept. Accordingly, we have interrogated five internationally renowned medical data bases: Elsevier, NCBI/PubMed, NCBI/PMC, PEDro, and ISI Web of Knowledge/Science (the last one to check whether the initially identified articles are published in ISI indexed journals), based on a large (details in the body text) number of most appropriate, to our knowledge, key word combinations/"syntaxes"-used contextually-and subsequently fulfilling the related, on five steps, filtering/selection methodology. We have thereby selected 114 fully eligible (of which contributive: 83-see further) papers; at the same time, additionally, we have enhanced our documentation-basically, but not exclusively, for the introductive part of this work (see further)-with bibliographic resources, overall connected to our subject, identified in the literature within a non-standardized search. It appears that the opportunity window for morph-functional recovery after stroke is larger than previously thought, actually being considered that brain neurorestoration/repair could occur, and therefore be expected, in later stages than in earlier ones, although, in this context, the number of cases possibly benefitting (for instance after physical and/or cognitive rehabilitation-including with magnetic or direct current transcranial stimulation) is quite small and with more or less conflicting, related outcomes, in the literature. Moreover, applying especially high intense, solicitating, rehabilitation interventions, in early stages post (including ischemic) stroke could even worsen the functional evolution. Accordingly, for clarifications and validation of more unitary points of view, continuing and boosting research efforts in this complex, interdisciplinary domain, is necessary. Until finding (if ever) effective modalities to cure the lesions of the central nervous system (CNS)-including post ischemic stroke-it is reasonable and recommendable-based on rigorous methodologies-the avail of combined ways: physiatric, pharmacologic, possibly also bio-technologic. On a different note, but however connected to our subject: periodic related systematic, synthetic literature reviews reappraisals are warranted and welcome.

Immediate effect of adding mirror visual feedback to lateral weight-shifting training on the standing balance control of the unilateral spatial neglect model

[Purpose] This study aimed to clarify the immediate effect of adding mirror visual feedback to lateral weight-shifting training on the standing balance control of the left unilateral spatial neglect model. [Participants and Methods] We included 64 healthy participants to create left unilateral spatial neglect models and divided them into four subgroups. Each subgroup received opposite lateral weight-shifting training with or without mirror visual feedback. We then evaluated the static and dynamic standing balance by measuring the center of pressure point alterations in the medial-lateral and anterior-posterior planes. We further evaluated the center of pressure length and bilateral load ratio. [Results] The center of pressure was significantly stable upon performing the eyes-open static standing balance test in the left weight-shifting training subgroup with mirror visual feedback. When participants performed the left dynamic standing balance test, the center of pressure moved significantly rightward and became significantly stable in the right weight-shifting training subgroup with mirror visual feedback. The left load ratio significantly decreased in the right weight-shifting training of subgroups that either did or did not receive mirror visual feedback upon performing the left dynamic standing balance test. [Conclusion] We concluded that adding mirror visual feedback to lateral weight-shifting training affected some measurements of standing balance control of the left unilateral spatial neglect model.

Mirror therapy for unilateral neglect after stroke: A systematic review

BACKGROUND AND PURPOSE

The effect of mirror therapy for unilateral neglect after stroke currently remains uncertain.

METHODS

This systematic review investigated the effect of mirror therapy on neglect and daily living activities in patients with unilateral neglect after stroke when compared with no treatment, sham mirror therapy, or routinely applied therapies only. We performed a systematic electronic search of PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Wanfang Data to identify relevant randomized control trials (RCTs).

RESULTS

We included five RCTs in the data synthesis. Mirror therapy (combined or not with other treatments) was more effective in improving neglect as compared with sham mirror therapy or no treatment (combined or not with the other therapies; standard mean difference [SMD] = 1.62, 95% confidence interval [CI] = 1.03-2.21, p < 0.00001). Mirror therapy (combined or not with other therapies) was effective in improving daily living activities as compared with sham mirror therapy or no treatment (combined or not with the other therapies; SMD = 2.09, 95% CI = 0.63-3.56, p = 0.005).

CONCLUSIONS

Our results show that mirror therapy effectively improves neglect and daily living activities in patients with unilateral neglect after stroke. Future trials with high methodological quality and larger sample sizes are needed to determine the immediate and long-term effect of appropriate mirror therapy protocol for unilateral neglect.

EEG-Based Evidence of Mirror Neuron Activity from App-Mediated Stroke Patient Observation

Background and Objectives: The mirror neuron system in the sensorimotor region of the cerebral cortex is equally activated during both action observation and execution. Action observation training mimics the functioning of the mirror neuron system, requiring patients to watch and imitate the actions necessary to perform activities of daily living. StrokeCare is a user-friendly application based on the principles of action observation training, designed to assist people recovering from stroke. Therefore, when observing the daily life behavior provided in the StrokeCare app, whether the MNS is activated and mu inhibition appears. Materials and Methods: We performed electroencephalography (EEG) on 24 patients with chronic stroke (infarction: 11, hemorrhage: 13) during tasks closely related to daily activities, such as dressing, undressing, and walking. The StrokeCare app provided action videos for patients to watch. Landscape imagery observation facilitated comparison among tasks. We analyzed the mu rhythm from the C3, CZ, and C4 regions and calculated the mean log ratios for comparison of mu suppression values. Results: The EEG mu power log ratios were significantly suppressed during action observation in dressing, undressing, walking, and landscape conditions, in decreasing order. However, there were no significant activity differences in the C3, C4 and CZ regions. The dressing task showed maximum suppression after a color spectrum was used to map the relative power values of the mu rhythm for each task. Conclusions: These findings reveal that the human mirror neuron system was more strongly activated during observation of actions closely related to daily life activities than landscape images.

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.

Mirror Visual Feedback Induces M1 Excitability by Disengaging Functional Connections of Perceptuo-Motor-Attentional Processes during Asynchronous Bimanual Movement: A Magnetoencephalographic Study

Mirror visual feedback (MVF) has been shown to increase the excitability of the primary motor cortex (M1) during asynchronous bimanual movement. However, the functional networks underlying this process remain unclear. We recruited 16 healthy volunteers to perform asynchronous bimanual movement, that is, their left hand performed partial range of movement while their right hand performed normal full range of movement. Their ongoing brain activities were recorded by whole-head magnetoencephalography during the movement. Participants were required to keep both hands stationary in the control condition. In the other two conditions, participants were required to perform asynchronous bimanual movement with MVF (Asy_M) and without MVF (Asy_w/oM). Greater M1 excitability was found under Asy_M than under Asy_w/oM. More importantly, when receiving MVF, the visual cortex reduced its functional connection to brain regions associated with perceptuo-motor-attentional process (i.e., M1, superior temporal gyrus, and dorsolateral prefrontal cortex). This is the first study to demonstrate a global functional network of MVF during asynchronous bimanual movement, providing a foundation for future research to examine the neural mechanisms of mirror illusion in motor control.

Effect of electro-acupuncture therapy on limb spasm and excitability of motor neurons in stroke rats

To investigate the effect of electro-acupuncture therapy on limb spasm and excitability of motor neurons in stroke rats. Ischemic stroke model was induced with middle cerebral artery embolization in SD rats. Thirty-three modeled rats were randomly divided into model group, electro-acupuncture group, and baclofen group with 11 rats in each group, and another 10 rats were taken as sham operation group. The electro-acupuncture group and the baclofen group were treated with electro-acupuncture and baclofen tablets respectively. The model group and the sham operation group had no intervention. The neural function was evaluated with Bederson's scale and balance beam test; the muscle tension was measured with electrophysiography; the pathological changes of brain tissue was examined with HE staining; the content of glutamic acid (Glu) and γ-aminobutyric acid (GABA) in rat cerebral cortex was analyze with enzyme linked immunosorbent assay (ELISA) method, the expression of metabotropic glutamate receptor 1a () and γ-aminobutyric acid type B receptor subunit 1 () mRNA were detected with RT-qPCR. Compared with the model group, the neurological function scores of the electro-acupuncture group and the baclofen group showed a downward trend at d7 after operation (all >0.05), and the neurological function scores of the electro-acupuncture group and the baclofen group were significantly decreased at d12 after the operation (all <0.05). Compared with sham operation group, the electrophysiological results of model group, electro-acupuncture group and baclofen group were significantly lower (all <0.05), and there was no statistical difference in the electrophysiological results of the model group, electro-acupuncture group and baclofen group at d7 after operation (all >0.05). Compared with the model group, the electrophysiological results of the electro-acupuncture group and baclofen group were significantly increased after operation (all <0.05). The results of HE staining showed that there was no cell edema and degeneration in the sham operation group, no pyknosis of the nucleus, and no bleeding in the interstitium. Cell edema and degeneration and mesenchymal congestion appeared in the model group. Compared with the model group, the cytoplasmic edema and degeneration and the interstitial bleeding in the electroacupuncture group and the baclofen group were reduced. Compared with sham operation group, the Glu content and the relative expression of mRNA was increased in the model group, electro-acupuncture group and baclofen group, while the GABA content and the relative expression of mRNA decreased (all <0.05). Compared with model group, the Glu content and the relative expression of mRNA in the electro-acupuncture group and baclofen group decreased, and the GABA content and relative expression of mRNA increased (all <0.05). Electro-acupuncture may improve limb spasm after stroke through regulating the expression of Glu and GABA in the cerebral cortex and the excitability of motor neurons in rats.

Event-Related Desynchronization During Mirror Visual Feedback: A Comparison of Older Adults and People After Stroke

Event-related desynchronization (ERD), as a proxy for mirror neuron activity, has been used as a neurophysiological marker for motor execution after mirror visual feedback (MVF). Using EEG, this study investigated ERD upon the immediate effects of single-session MVF in unimanual arm movements compared with the ERD effects occurring without a mirror, in two groups: stroke patients with left hemiplegia and their healthy counterparts. During EEG recordings, each group performed one session of mirror therapy training in three task conditions: with a mirror, with no mirror, and with a covered mirror. An asymmetry index was calculated from the subtraction of the event-related spectrum perturbations between the C3 and C4 electrodes located over the sensorimotor cortices contralateral and ipsilateral to the moved arm. Results of the effect of task versus group in contralateral and ipsilateral motor areas showed that there was a significant effect of task condition at the contralateral motor area in the high beta band (17–35 Hz) at C3. High beta ERD showed that the suppression was greater over the contralateral hemisphere than it was over the ipsilateral hemisphere in both study groups. The magnitude of low beta (12–16 Hz) ERD in patients with stroke was more suppressed in contralesional C3 under the no mirror compared to that of the covered mirror and similarly more suppressed in ipsilesional C4 ERD under the no mirror compared to that of the mirror condition. The correlation analysis revealed that the magnitude of ERSP power correlated significantly with arm severity in the low and high beta bands in patients with stroke, and a higher asymmetry index in the low beta band was associated with higher arm functioning under the no-mirror condition. There was a shift in sensorimotor ERD toward the contralateral hemisphere as induced by MVF accompanying unimanual movement in both stroke patients and healthy controls. The use of ERD in the low beta band as a neurophysiological marker to indicate the relationships between the amount of MVF-induced ERD attenuation and motor severity, and the outcome indicator for improving stroke patients’ neuroplasticity in clinical trials using MVF are warranted to be explored in the future.

The Modulatory Effects of Intermittent Theta Burst Stimulation in Combination With Mirror Hand Motor Training on Functional Connectivity: A Proof-of-Concept Study

Mirror training (MT) is an observation-based motor learning strategy. Intermittent theta burst stimulation (iTBS) is an accelerated form of excitatory repetitive transcranial magnetic stimulation (rTMS) that has been used to enhance the cortical excitability of the motor cortices. This study aims to investigate the combined effects of iTBS with MT on the resting state functional connectivity at alpha frequency band in healthy adults. Eighteen healthy adults were randomized into one of three groups—Group 1: iTBS plus MT, Group 2: iTBS plus sham MT, and Group 3: sham iTBS plus MT. Participants in Groups 1 and 3 observed the mirror illusion of the moving (right) hand in a plain mirror for four consecutive sessions, one session/day, while participants in Group 2 received the same training with a covered mirror. Real or sham iTBS was applied daily over right motor cortex prior to the training. Resting state electroencephalography (EEG) at baseline and post-training was recorded when participants closed their eyes. The mixed-effects model demonstrated a significant interaction effect in the coherence between FC4 and C4 channels, favoring participants in Group 1 over Group 3 (Δβ = −0.84, p = 0.048). A similar effect was also found in the coherence between FC3 and FC4 channels favoring Group 1 over Group 3 (Δβ = −0.43, p = 0.049). In contrast to sham iTBS combined with MT, iTBS combined with MT may strengthen the functional connectivity between bilateral premotor cortices and ipsilaterally within the motor cortex of the stimulated hemisphere. In contrast to sham MT, real MT, when combined with iTBS, might diminish the connectivity among the contralateral parietal–frontal areas.

Modulation of Interhemispheric Inhibition between Primary Motor Cortices Induced by Manual Motor Imitation: A Transcranial Magnetic Stimulation Study

Imitation has been proven effective in motor development and neurorehabilitation. However, the relationship between imitation and interhemispheric inhibition (IHI) remains unclear. Transcranial magnetic stimulation (TMS) can be used to investigate IHI. In this study, the modification effects of IHI resulting from mirror neuron system (MNS) activation during different imitations are addressed. We measured IHI between homologous primary motor cortex (M1) by analyzing the ipsilateral silent period (iSP) evoked by single-pulse focal TMS during imitation and analyzed the respective IHI modulation during and after different patterns of imitation. Our main results showed that throughout anatomical imitation, significant time-course changes of iSP duration through the experiment were observed in both directions. iSP duration declined from the pre-imitation time point to the post-imitation time point and did not return to baseline after 30 min rest. We also observed significant iSP reduction from the right hemisphere to the left hemisphere during anatomical and specular imitation, compared with non-imitative movement. Our findings indicate that using anatomical imitation in action observation and execution therapy promotes functional recovery in neurorehabilitation by regulating IHI.

The Effects of Priming Intermittent Theta Burst Stimulation on Movement-Related and Mirror Visual Feedback-Induced Sensorimotor Desynchronization

The potential benefits of priming intermittent theta burst stimulation (iTBS) with continuous theta burst stimulation (cTBS) have not been examined in regard to sensorimotor oscillatory activities recorded in electroencephalography (EEG). The objective of this study was to investigate the modulatory effect of priming iTBS (cTBS followed by iTBS) delivered to the motor cortex on movement-related and mirror visual feedback (MVF)-induced sensorimotor event-related desynchronization (ERD), compared with iTBS alone, on healthy adults. Twenty participants were randomly allocated into Group 1: priming iTBS—cTBS followed by iTBS, and Group 2: non-priming iTBS—sham cTBS followed by iTBS. The stimulation was delivered to the right primary motor cortex daily for 4 consecutive days. EEG was measured before and after 4 sessions of stimulation. Movement-related ERD was evaluated during left-index finger tapping and MVF-induced sensorimotor ERD was evaluated by comparing the difference between right-index finger tapping with and without MVF. After stimulation, both protocols increased movement-related ERD and MVF-induced sensorimotor ERD in high mu and low beta bands, indicated by significant time effects. A significant interaction effect favoring Group 1 in enhancing movement-related ERD was observed in the high mu band [F_(1,18) = 4.47, p = 0.049], compared with Group 2. Our experiment suggests that among healthy adults priming iTBS with cTBS delivered to the motor cortex yields similar effects with iTBS alone on enhancing ERD induced by MVF-based observation, while movement-related ERD was more enhanced in the priming iTBS condition, specifically in the high mu band.

Virtual Rehabilitation of the Paretic Hand and Arm in Persons With Stroke: Translation From Laboratory to Rehabilitation Centers and the Patient's Home

The anatomical and physiological heterogeneity of strokes and persons with stroke, along with the complexity of normal upper extremity movement make the possibility that any single treatment approach will become the definitive solution for all persons with upper extremity hemiparesis due to stroke unlikely. This situation and the non-inferiority level outcomes identified by many studies of virtual rehabilitation are considered by some to indicate that it is time to consider other treatment modalities. Our group, among others, has endeavored to build on the initial positive outcomes in studies of virtual rehabilitation by identifying patient populations, treatment settings and training schedules that will best leverage virtual rehabilitation's strengths. We feel that data generated by our lab and others suggest that (1) persons with stroke may adapt to virtual rehabilitation of hand function differently based on their level of impairment and stage of recovery and (2) that less expensive, more accessible home based equipment seems to be an effective alternative to clinic based treatment that justifies continued optimism and study.

Improving performance in motor imagery BCI-based control applications via virtually embodied feedback

OBJECTIVE

Brain-computer interfaces (BCIs) based on motor imagery (MI) are commonly used for control applications. However, these applications require strong and discriminant neural patterns for which extensive experience in MI may be necessary. Inspired by the field of rehabilitation where embodiment is a key element for improving cortical activity, our study proposes a novel control scheme in which virtually embodiable feedback is provided during control to enhance performance.

METHODS

Subjects underwent two immersive virtual reality control scenarios in which they controlled the two-dimensional movement of a device using electroencephalography (EEG). The two scenarios only differ on whether embodiable feedback, which mirrors the movement of the classified intention, is provided. After undergoing each scenario, subjects also answered a questionnaire in which they rated how immersive the scenario and embodiable the feedback were.

RESULTS

Subjects exhibited higher control performance, greater discriminability in brain activity patterns, and enhanced cortical activation when using our control scheme compared to the standard control scheme in which embodiable feedback is absent. Moreover, the self-rated embodiment and presence scores showed significantly positive linear relationships with performance.

SIGNIFICANCE

The findings in our study provide evidence that providing embodiable feedback as guidance on how intention is classified may be effective for control applications by inducing enhanced neural activity and patterns with greater discriminability. By applying embodiable feedback to immersive virtual reality, our study also serves as another instance in which virtual reality is shown to be a promising tool for improving MI.