Feasibility of a neurorehabilitation pipeline and an automated algorithm to select appropriate treatments for upper extremity motor paralysis in individuals with chronic stroke.

OBJECTIVE: This study aimed to investigate the feasibility of a neurorehabilitation pipeline and develop an algorithm to automatically select the appropriate treatment for individuals with upper extremity motor paralysis after stroke in the chronic phase. DESIGN: In Experiment 1, eight post-stroke participants in the chronic phase who underwent treatment sustaining two to three phases were assessed before and after treatment. In Experiment 2, a decision tree analysis was performed in which the dependent variable was set as the treatment option determined by a board-certified physiatrist for 95 post-stroke participants; the independent variables were only motor function scores or both motor function scores and electromyogram variables. RESULTS: In Experiment 1, the clinical assessment scores were improved significantly after treatment. Experiment 2 showed that the agreements of the model with only motor function scores as the dependent variable and with motor function scores and electromyogram variables as the dependent variables were 75.8% and 82.1%, respectively. CONCLUSIONS: This novel treatment package is feasible for improvement of motor function in post-stroke individuals with severe motor paralysis. The study also established an automated algorithm for selecting appropriate treatments for upper extremity motor paralysis after stroke, identifying standard values of key variables, including electromyography variables.

Effects of a Stimulus Response Task Using Virtual Reality on Unilateral Spatial Neglect: A Randomized Controlled Trial.

OBJECTIVE: To investigate the effects of a stimulus response task using virtual reality (VR) for unilateral spatial neglect (USN). DESIGN: Double-blind randomized controlled trial. SETTING: Acute phase hospital where stroke patients are hospitalized. PARTICIPANTS: The participants were 42 patients (N=42) with right-hemisphere cerebral damage who had been experiencing USN in their daily lives. They were randomly assigned to 3 groups: a stimulus response task with a background shift (SR+BS group), a stimulus response task without a background shift (SR group), and an object gazing task (control group). INTERVENTIONS: The stimulus response task was to search for balloons that suddenly appeared on the VR screen. A background shift was added to highlight the search in the neglected space. The control task was to maintain a controlled gaze on a balloon that appeared on the VR screen. The intervention period was 5 days. MAIN OUTCOME MEASURES: The primary outcome was the participants' scores on a stimulus-driven attention test (SAT) using the reaction time. The stimuli of the SAT were divided into 6 blocks of 3 lines on each side (-3 to +3). The secondary outcomes were their scores on the Behavioral Intention Test conventional, Catherine Bergego Scale, and straight ahead pointing tests. RESULTS: In the SAT, there were significant interaction effects of reaction time between time and group factors in left-2, right+2, and right+3. The SR+BS and SR groups showed significant improvements in the reaction time of left-2 and right+3 compared with the control group. Moreover, the SR+BS group showed a significant improvement in the reaction time of left-2, which was the neglected space, compared with the SR group. However, there were no significant interaction effects of Behavioral Intention Test conventional, Catherine Bergego Scale, and straight ahead pointing. CONCLUSIONS: Our results suggest that the use of stimulus response tasks using VR combined with background shifts may improve left-sided USN.

Relationship between resting-state functional connectivity and change in motor function after motor imagery intervention in patients with stroke: a scoping review.

BACKGROUND: In clinical practice, motor imagery has been proposed as a treatment modality for stroke owing to its feasibility in patients with severe motor impairment. Motor imagery-based interventions can be categorized as open- or closed-loop. Closed-loop intervention is based on voluntary motor imagery and induced peripheral sensory afferent (e.g., Brain Computer Interface (BCI)-based interventions). Meanwhile, open-loop interventions include methods without voluntary motor imagery or sensory afferent. Resting-state functional connectivity (rs-FC) is defined as a significant temporal correlated signal among functionally related brain regions without any stimulus. rs-FC is a powerful tool for exploring the baseline characteristics of brain connectivity. Previous studies reported changes in rs-FC after motor imagery interventions. Systematic reviews also reported the effects of motor imagery-based interventions at the behavioral level. This study aimed to review and describe the relationship between the improvement in motor function and changes in rs-FC after motor imagery in patients with stroke. REVIEW PROCESS: The literature review was based on Arksey and O'Malley's framework. PubMed, Ovid MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science were searched up to September 30, 2023. The included studies covered the following topics: illusion without voluntary action, motor imagery, action imitation, and BCI-based interventions. The correlation between rs-FC and motor function before and after the intervention was analyzed. After screening by two independent researchers, 13 studies on BCI-based intervention, motor imagery intervention, and kinesthetic illusion induced by visual stimulation therapy were included. CONCLUSION: All studies relating to motor imagery in this review reported improvement in motor function post-intervention. Furthermore, all those studies demonstrated a significant relationship between the change in motor function and rs-FC (e.g., sensorimotor network and parietal cortex).

Combined Ankle Robot Training and Robot-assisted Gait Training Improved the Gait Pattern of a Patient with Chronic Traumatic Brain Injury.

Background: : Walking disability caused by central nervous system injury often lingers. In the chronic phase, there is great need to improve walking speed and gait, even for patients who walk independently. Robot-assisted gait training (RAGT) has been widely used, but few studies have focused on improving gait patterns, and its effectiveness for motor function has been limited. This report describes the combination of "RAGT to learn the gait pattern" and "ankle robot training to improve motor function" in a patient with chronic stage brain injury. Case: : A 34-year-old woman suffered a traumatic brain injury 5 years ago. She had residual right hemiplegia [Fugl-Meyer Assessment-Lower Extremity (FMA-LE): 18 points] and mild sensory impairment, but she walked independently with a short leg brace and a cane. Her comfortable gait speed was 0.57 m/s without an orthosis, and her 6-m walk test distance was 240 m. The Gait Assessment and Intervention Tool (G.A.I.T.) score was 35 points. After hospitalization, ankle robot training was performed daily, with RAGT performed 10 times in total. Post-intervention evaluation performed on Day 28 showed: FMA-LE, 23 points; comfortable walking speed, 0.69 m/s; G.A.I.T., 27 points; and three-dimensional motion analysis showed ankle dorsiflexion improved from 3.22° to 12.59° and knee flexion improved from 1.75° to 16.54° in the swing phase. Discussion: : This is one of few studies to have examined the combination of two robots. Combining the features of each robot improved the gait pattern and motor function, even in the chronic phase.

Virtual reality-based gait rehabilitation intervention for stroke individuals: a scoping review.

Virtual reality (VR)-based rehabilitation is rapidly gaining interest and has been shown to be an intervention to facilitate motor learning in balance and gait rehabilitation. A review of the current literature is needed to provide an overview of the current state of knowledge of VR-based gait physiotherapy for stroke patients. A systematic literature search was performed in PubMed and Scopus. Search terms included: "virtual reality," "stroke," "gait," and "physical therapy." Articles published in a peer-reviewed journal between 2017 and 2021 were considered. The intervention was mainly related to the use of VR as a therapeutic modality, and the outcome was gait performance. The initial search identified 329 articles. After an eligibility review, 13 articles that met the inclusion criteria were included in the study. Most of participants were in a chronic stage and were between 14 and 85 years old. The VR-based gait training ranged from nonimmersive to immersive, was mostly performed on a treadmill, and was usually combined with conventional physiotherapy. The duration of the program varied from 10 to 60 min, and there were about 9 to 30 sessions. VR-based gait rehabilitation has a positive effect on gait ability. The existing literature suggests that VR-based rehabilitation combined with conventional physiotherapy could improve gait ability of people with stroke, especially in the chronic stage. However, the duration of VR-based programs should be customized to suit individuals to avoid stimulation sickness. Further research is needed to investigate the long-term effects of this approach.

Neural bases characterizing chronic and severe upper-limb motor deficits after brain lesion.

Chronic and severe upper-limb motor deficits can result from damage to the corticospinal tract. However, it remains unclear what their characteristics are and whether only corticospinal tract damage determines their characteristics. This study aimed to investigate the clinical characteristics and neural bases of chronic and severe upper-limb motor deficits. Motor deficits, including spasticity, of 45 patients with brain lesions were assessed using clinical scales. Regarding their scores, we conducted a principal component analysis that statistically extracted the clinical characteristics as two principal components. Using these principal components, we investigated the neural bases underlying their characteristics through lesion analyses of lesion volume, lesion sites, corticospinal tract, or other regional white-matter integrity. Principal component analysis showed that the clinical characteristics of chronic and severe upper-limb motor deficits could be described as a comprehensive severity and a trade-off relationship between proximal motor functions and wrist/finger spasticity. Lesion analyses revealed that the comprehensive severity was correlated with corticospinal tract integrity, and the trade-off relationship was associated with the integrity of other regional white matter located anterior to the posterior internal capsule, such as the anterior internal capsule. This study indicates that the severity of chronic and severe upper-limb motor deficits can be determined according to the corticospinal tract integrity, and such motor deficits may be further characterized by the integrity of other white matter, where the corticoreticular pathway can pass through, by forming a trade-off relationship where patients have higher proximal motor functions but more severe wrist/finger spasticity, and vice versa.

Effects of a visual search task in a virtual reality space with a moving background on spatial cognition and standing balance in patients with left hemiparetic stroke.

We examined effects of a visual search task (VST) in virtual reality (VR) with a moving background on spatial cognition and standing balance in left hemiparetic strokes. The VST with background deviation was allocated to Case A. In Case B, the VST without the deviation was performed. As a results, in Case A, the reaction time of VST was shortened in the paretic space and ability of weight-shift to the paretic side was improved. In conclusion, the VST in the VR with a spatial manipulation may improve spatial cognition and standing balance in left hemiparetic strokes.

Effect of exoskeleton-assisted Body Weight-Supported Treadmill Training on gait function for patients with chronic stroke: a scoping review.

BACKGROUND: Therapeutic exercise for gait function using an exoskeleton-assisted Body Weight Supported Treadmill Training (BWSTT) has been identified as a potential intervention that allows for task-based repetitive training with appropriate kinematics while adjusting the amount of body weight support (BWS). Nonetheless, its effect on gait in patients with stroke in the chronic phase are yet to be clarified. The primary aim of this scoping review was to present the status of effectiveness of exoskeleton-assisted BWSTT in patients with chronic stroke. The secondary aims were to summarise intervention protocols, types and functions of BWSTT exoskeletal robotic devices currently used clinically. METHOD AND RESULTS: Articles were accessed and collected from PubMed, Ovid MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science databases, which were completed in October 2020. Articles were included if the subjects were adults with stroke in the chronic phase (onset ≥ 6 months) and if they utilised a robotic exoskeleton with treadmill and body weight support and investigated the efficacy of gait exercise. A total of 721 studies were identified, of which 11 randomised controlled trials were selected. All included studies were published from 2008 to 2020. Overall, 309 subjects were enrolled; of these, 241 (156 males, 85 females) participated. Walking outcome measures were used more often to evaluate the functional aspects of gait than to evaluate gait independence. In 10 of 11 studies, showed the effectiveness of exoskeleton robot-assisted BWSTT in terms of outcomes contributing to improved gait function. Two studies reported that exoskeleton-assisted BWSTT with combination therapy was significantly more effective in improving than exoskeleton-assisted BWSTT alone. However, no significant difference was identified between the groups; compared with therapist-assisted BWSTT groups, exoskeleton-assisted BWSTT groups did not exhibit significant change. CONCLUSION: This review suggests that exoskeleton-assisted BWSTT for patients with chronic stroke may be effective in improving walking function. However, the potential may be "to assist" and not because of using the robot. Further studies are required to verify its efficacy and strengthen evidence on intervention protocols.

The effects of robot-assisted gait training combined with non-invasive brain stimulation on lower limb function in patients with stroke and spinal cord injury: A systematic review and meta-analysis.

Objective: This study aimed to investigate the effect of robot-assisted gait training (RAGT) therapy combined with non-invasive brain stimulation (NIBS) on lower limb function in patients with stroke and spinal cord injury (SCI). Data sources: PubMed, Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and Web of Science were searched. Study selection: Randomized controlled trials (RCTs) published as of 3 March 2021. RCTs evaluating RAGT combined with NIBS, such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), for lower limb function (e.g., Fugl-Meyer assessment for patients with stroke) and activities (i.e., gait velocity) in patients with stroke and SCI were included. Data extraction: Two reviewers independently screened the records, extracted the data, and assessed the risk of bias. Data synthesis: A meta-analysis of five studies (104 participants) and risk of bias were conducted. Pooled estimates demonstrated that RAGT combined with NIBS significantly improved lower limb function [standardized mean difference (SMD) = 0.52; 95% confidence interval (CI) = 0.06-0.99] but not lower limb activities (SMD = -0.13; 95% CI = -0.63-0.38). Subgroup analyses also failed to find a greater improvement in lower limb function of RAGT with tDCS compared to sham stimulation. No significant differences between participant characteristics or types of NIBS were observed. Conclusion: This meta-analysis demonstrated that RAGT therapy in combination with NIBS was effective in patients with stroke and SCI. However, a greater improvement in lower limb function and activities were not observed using RAGT with tDCS compared to sham stimulation.

Effects of kinesthetic illusion induced by visual stimulation (KINVIS) therapy on patients with stroke in the subacute phase: a visual analysis based on paralysis severity.

We explored the effect of kinesthetic illusion induced by visual stimulation (KINVIS) therapy on motor function in patients with stroke during the subacute phase based on paralysis severity. The study was performed using an ABAB design (A1, B1, A2, B2; for 10 days each). KINVIS therapy was additionally administered in periods B1 and B2. Ten patients with stroke were classified according to severity. The improvement in upper limb motor function was higher after B1 and B2 than after A1 and A2 in the moderate group. The effect of KINVIS therapy increases the degree of improvement in motor function, especially in the moderate group.

Visually Induced Kinaesthetic Illusion Combined with Therapeutic Exercise for Patients with Chronic Stroke: A Pilot Study.

OBJECTIVE: Kinaesthetic perceptional illusion by visual stimulation (KINVIS) combined with neuromuscular electrical stimulation (NMES) and conventional therapeutic exercise (TherEX) has been shown previously to enhance motor function in stroke patients with chronic hemiparesis. The aim of this preliminary study is to assess the effects of a repetitive KINVIS intervention combined with TherEX, but without NMES, on upper limb motor function of patients with stroke-induced hemiparesis. DESIGN: A quasi-experimental study, with pretest-posttest for 1 group Patients: Ten patients with stroke-induced, chronic, severe upper limb hemiparesis. METHODS: Patients were evaluated before and after a 10-day intervention, during which KINVIS and TherEX were applied for 20 and 60 min, respectively, for 5 days per week (Monday to Friday). Upper limb motor function was assessed using Fugl-Meyer Assessment (FMA) and Action Research Arm Test (ARAT), and resistance to passive movement in flexor muscles was assessed using the Modified Ashworth Scale (MAS). In addition, the amount of use and quality of movement of the affected upper limb in daily life were assessed using Motor Activity Log (MAL). RESULTS: Clinical assessments with FMA, ARAT, MAS, and MAL significantly improved after the intervention period. CONCLUSION: A repetitive KINVIS intervention combined with TherEX may improve upper limb motor function in patients with chronic stroke and severe hemiparesis.

Influence of Visual Stimulation-Induced Passive Reproduction of Motor Images in the Brain on Motor Paralysis After Stroke.

Finger flexor spasticity, which is commonly observed among patients with stroke, disrupts finger extension movement, consequently influencing not only upper limb function in daily life but also the outcomes of upper limb therapeutic exercise. Kinesthetic illusion induced by visual stimulation (KINVIS) has been proposed as a potential treatment for spasticity in patients with stroke. However, it remains unclear whether KINVIS intervention alone could improve finger flexor spasticity and finger extension movements without other intervention modalities. Therefore, the current study investigated the effects of a single KINVIS session on finger flexor spasticity, including its underlying neurophysiological mechanisms, and finger extension movements. To this end, 14 patients who experienced their first episode of stroke participated in this study. A computer screen placed over the patient's forearm displayed a pre-recorded mirror image video of the patient's non-paretic hand performing flexion-extension movements during KINVIS. The position and size of the artificial hand were adjusted appropriately to create a perception that the artificial hand was the patient's own. Before and after the 20-min intervention, Modified Ashworth Scale (MAS) scores and active range of finger extension movements of the paretic hand were determined. Accordingly, MAS scores and active metacarpophalangeal joint extension range of motion improved significantly after the intervention. Moreover, additional experimentation was performed using F-waves on eight patients whose spasticity was reduced by KINVIS to determine whether the same intervention also decreased spinal excitability. Our results showed no change in F-wave amplitude and persistence after the intervention. These results demonstrate the potential clinical significance of KINVIS as a novel intervention for improving finger flexor spasticity and extension movements, one of the most significant impairments among patients with stroke. The decrease in finger flexor spasticity following KINVIS may be attributed to neurophysiological changes not detectable by the F-wave, such as changes in presynaptic inhibition of Ia afferents. Further studies are certainly needed to determine the long-term effects of KINVIS on finger spasticity, as well as the neurophysiological mechanisms explaining the reduction in spasticity.

The Effects of Transcranial Direct Current Stimulation on Dual-Task Interference Depend on the Dual-Task Content.

Recently, some studies revealed that transcranial direct current stimulation (tDCS) reduces dual-task interference. Since there are countless combinations of dual-tasks, it remains unclear whether stable effects by tDCS can be observed on dual-task interference. An aim of the present study was to investigate whether the effects of tDCS on dual-task interference change depend on the dual-task content. We adopted two combinations of dual-tasks, i.e., a word task while performing a tandem task (word-tandem dual-task) and a classic Stroop task while performing a tandem task (Stroop-tandem dual-task). We expected that the Stroop task would recruit the dorsolateral prefrontal cortex (DLPFC) and require involvement of executive function to greater extent than the word task. Subsequently, we hypothesized that anodal tDCS over the DLPFC would improve executive function and result in more effective reduction of dual-task interference in the Stroop-tandem dual-task than in the word-tandem dual-task. Anodal or cathodal tDCS was applied over the DLPFC or the supplementary motor area using a constant current of 2.0 mA for 20 min. According to our results, dual-task interference and the task performances of each task under the single-task condition were not changed after applying any settings of tDCS. However, anodal tDCS over the left DLPFC significantly improved the word task performance immediately after tDCS under the dual-task condition. Our findings suggested that the effect of anodal tDCS over the left DLPFC varies on the task performance under the dual-task condition was changed depending on the dual-task content.

Model-Based Analyses for the Causal Relationship Between Post-stroke Impairments and Functional Brain Connectivity Regarding the Effects of Kinesthetic Illusion Therapy Combined With Conventional Exercise.

Aims: Therapy with kinesthetic illusion of segmental body part induced by visual stimulation (KINVIS) may allow the treatment of severe upper limb motor deficits in post-stroke patients. Herein, we investigated: (1) whether the effects of KINVIS therapy with therapeutic exercise (TherEx) on motor functions were induced through improved spasticity, (2) the relationship between resting-state functional connectivity (rs-FC) and motor functions before therapy, and (3) the baseline characteristics of rs-FC in patients with the possibility of improving their motor functions. Methods: Using data from a previous clinical trial, three path analyses in structural equation modeling were performed: (1) a mediation model in which the indirect effects of the KINVIS therapy with TherEx on motor functions through spasticity were drawn, (2) a multiple regression model with pre-test data in which spurious correlations between rs-FC and motor functions were controlled, and (3) a multiple regression model with motor function score improvements between pre- and post-test in which the pre-test rs-FC associated with motor function improvements was explored. Results: The mediation model illustrated that although KINVIS therapy with TherEx did not directly improve motor function, it improved spasticity, which led to ameliorated motor functions. The multiple regression model with pre-test data suggested that rs-FC of bilateral parietal regions is associated with finger motor functions, and that rs-FC of unaffected parietal and premotor areas is involved in shoulder/elbow motor functions. Moreover, the multiple regression model with motor function score improvements suggested that the weaker the rs-FC of bilateral parietal regions or that of the supramarginal gyrus in an affected hemisphere and the cerebellar vermis, the greater the improvement in finger motor function. Conclusion: The effects of KINVIS therapy with TherEx on upper limb motor function may be mediated by spasticity. The rs-FC, especially that of bilateral parietal regions, might reflect potentials to improve post-stroke impairments in using KINVIS therapy with TherEx.

Effect of primary motor cortex excitability changes after quadripulse transcranial magnetic stimulation on kinesthetic sensitivity: A preliminary study.

Muscle spindles provide the greatest contribution to kinesthetic perception. Primary motor cortex (M1) excitability changes in parallel with the intensity of kinesthetic perception inputs from muscle spindles; M1 is therefore involved in kinesthetic perception. However, the causal relationship between changes in kinesthetic sensitivity and M1 excitability is unclear. The purpose of this study was to test whether artificially and sustainably modulated M1 excitability causes changes in kinesthetic sensitivity in healthy individuals. We evaluated motor evoked potentials (MEP) in Experiment 1 and joint motion detection thresholds (JMDT) in Experiment 2 before and after quadripulse transcranial magnetic stimulation (QPS). Nine healthy right-handed male volunteers were recruited. In each experiment, participants received QPS or sham stimulation (Sham) on separate days. MEP amplitude and JMDT were recorded before and at 0, 15, 30, 45, and 60 min after QPS and Sham. Our results showed that M1 excitability and kinesthetic sensitivity increased after QPS, whereas neither changed after Sham. In the five subjects who participated in both experiments, there was a significant moderate correlation between M1 excitability and kinesthetic sensitivity. Thus, the long-lasting change in kinesthetic sensitivity may be due to changes in M1 excitability. In addition, M1 may play a gain adjustment role in the neural pathways of muscle spindle input.

Kinesthetic illusion induced by visual stimulation influences sensorimotor event-related desynchronization in stroke patients with severe upper-limb paralysis: A pilot study.

BACKGROUND: Repetition of motor imagery improves the motor function of patients with stroke. However, patients who develop severe upper-limb paralysis after chronic stroke often have an impaired ability to induce motor imagery. We have developed a method to passively induce kinesthetic perception using visual stimulation (kinesthetic illusion induced by visual stimulation [KINVIS]). OBJECTIVE: This pilot study further investigated the effectiveness of KINVIS in improving the induction of kinesthetic motor imagery in patients with severe upper-limb paralysis after stroke. METHODS: Twenty participants (11 with right hemiplegia and 9 with left hemiplegia; mean time from onset [±standard deviation], 67.0±57.2 months) with severe upper-limb paralysis who could not extend their paretic fingers were included in this study. The ability to induce motor imagery was evaluated using the event-related desynchronization (ERD) recorded during motor imagery before and after the application of KINVIS for 20 min. The alpha- and beta-band ERDs around the premotor, primary sensorimotor, and posterior parietal cortices of the affected and unaffected hemispheres were evaluated during kinesthetic motor imagery of finger extension and before and after the intervention. RESULTS: Beta-band ERD recorded from the affected hemisphere around the sensorimotor area showed a significant increase after the intervention, while the other ERDs remained unchanged. CONCLUSIONS: In patients with chronic stroke who were unable to extend their paretic fingers for a prolonged period of time, the application of KINVIS, which evokes kinesthetic perception, improved their ability to induce motor imagery. Our findings suggest that although KINVIS is a passive intervention, its short-term application can induce changes related to the motor output system.

Feasibility Case Study for Treating a Patient with Sensory Ataxia Following a Stroke with Kinesthetic Illusion Induced by Visual Stimulation.

BACKGROUND: Sensory ataxia is a disorder of movement coordination caused by sensory deficits, especially in kinesthetic perception. Visual stimulus-induced kinesthetic illusion (KINVIS) is a method used to provide vivid kinesthetic perception without peripheral sensory input by using a video showing pre-recorded limb movements while the actual limb remains stationary. We examined the effects of KINVIS intervention in a patient with sensory ataxia. CASE: The patient was a 59-year-old man with a severe proprioceptive deficit caused by left thalamic hemorrhage. During KINVIS intervention, a computer screen displayed a pre-recorded mirror image video of the patient's unaffected hand performing flexion-extension movements as if it were attached to the patient's affected forearm. Kinematics during the flexion-extension movements of the paretic hand were recorded before and after 20-min interventions. Transcranial magnetic stimulation was applied to the affected and non-affected hemispheres. The amplitude of the motor-evoked potential (MEP) at rest was recorded for the muscles of both hands. After the intervention, the total trajectory length and the rectangular area bounding the trajectory of the index fingertip decreased. The MEP amplitude of the paretic hand increased, whereas the MEP amplitude of the non-paretic hand was unchanged. DISCUSSION: The changes in kinematics after the intervention suggested that KINVIS therapy may be a useful new intervention for sensory ataxia, a condition for which few effective treatments are currently available. Studies in larger numbers of patients are needed to clarify the mechanisms underlying this therapeutic effect.

Motor imagery combined with action observation training optimized for individual motor skills further improves motor skills close to a plateau.

The acquisition of high-level motor skills beyond a "plateau" is important in sports training and rehabilitation. We aimed to investigate whether motor skills close to a plateau state can be improved further by performing motor imagery (MI) training while observing movements with difficulty levels optimized for individual motor skills. The subjects were divided randomly into four groups (n = 10 per group): the control group and three groups of MI combined with action observation (MI + AO) training with varying difficulty levels. The task was to rotate the two cork balls 20 times counterclockwise using the left hand. The subjects performed 30 and 10 successful trials of this task before and after MI + AO training, respectively. In the three training groups, MI training was performed while observing videos showing ball rotation movements adjusted to the same level, a moderately higher level, or a remarkably higher level of difficulty than that achieved by the individual subjects. The improvement rate of the ball rotation time after MI + AO training was significantly higher in the moderate-difficulty than in the control group and remarkably higher level of difficulty group. The other two MI + AO training groups did not differ significantly compared with the control group. The vividness of the MI during MI + AO training was significantly greater in the moderate-difficulty vs. the remarkably-high-difficulty group. These results suggest that performing MI training while observing movement at a level that is moderately higher than an individual's ability can promote improvements in motor skills (close to a plateau state) in rehabilitation and sports training. The vividness of MI may be an important index for determining the difficulty level of the movement to be observed during MI + AO training.

Region-dependent bidirectional plasticity in M1 following quadripulse transcranial magnetic stimulation in the inferior parietal cortex.

BACKGROUND: The ability to manipulate the excitability of the network between the inferior parietal lobule (IPL) and primary motor cortex (M1) may have clinical value. OBJECTIVE: To investigate the possibility of inducing long-lasting changes in M1 excitability by applying quadripulse transcranial magnetic stimulation (QPS) to the IPL, and to ascertain stimulus condition- and site-dependent differences in the effects. METHODS: QPS was applied to M1, the primary somatosensory cortex (S1), the supramarginal gyrus (SMG) and angular gyrus (AG) IPL areas, with the inter-stimulus interval (ISI) in the train of pulses set to either 5 ms (QPS-5) or 50 ms (QPS-50). QPS was repeated at 0.2 Hz for 30 min, or not presented (sham condition). Excitability changes in the target site were examined by means of single-pulse transcranial magnetic stimulation (TMS). RESULTS: QPS-5 and QPS-50 at M1 increased and decreased M1 excitability, respectively. QPS at S1 induced no obvious change in M1 excitability. However, QPS at the SMG induced mainly suppressive effects in M1 for at least 30 min, regardless of the ISI length. Both QPS ISIs at the AG yielded significantly different MEP compared to those at the SMG. Thus, the direction of the plastic effect of QPS differed depending on the site, even under the same stimulation conditions. CONCLUSIONS: QPS at the IPL produced long-lasting changes in M1 excitability, which differed depending on the precise stimulation site within the IPL. These results raise the possibility of noninvasive induction of functional plasticity in M1 via input from the IPL.

Neural mechanism of selective finger movement independent of synergistic movement.

Muscle synergy is important for simplifying functional movement, which constitutes spatiotemporal patterns of activity across muscles. To execute selective finger movements that are independent of synergistic movement patterns, we hypothesized that inhibitory neural activity is necessary to suppress enslaved finger movement caused by synergist muscles. To test this hypothesis, we focused on a pair of synergist muscles used in the hand opening movement, namely the index finger abductor and little finger abductor (abductor digiti minimi; ADM), and examined whether inhibitory neural activity in ADM occurs during selective index finger abduction/adduction movements and/or its imagery using transcranial magnetic stimulation and F-wave analysis. During the index finger adduction movement, background EMG activity, F-wave persistence, and motor evoked potential (MEP) amplitude in ADM were elevated. However, during the index finger abduction movement, ADM MEP amplitude remained unchanged despite increased background EMG activity and F-wave persistence. These results suggest that increased spinal excitability in ADM is counterbalanced by cortical-mediated inhibition only during selective index finger abduction movement. This assumption was further supported by the results of motor imagery experiments. Although F-wave persistence in ADM increased only during motor imagery of index finger abduction, ADM MEP amplitude during motor imagery of index finger abduction was significantly lower than that during adduction. Overall, our findings indicate that cortical-mediated inhibition contributes to the execution of selective finger movements that are independent of synergistic hand movement patterns.