Primary motor cortex excitability is modulated with bimanual training

A Training Program Using Modified Joystick-Operated Ride-on Toys to Complement Conventional Upper Extremity Rehabilitation in Children with Cerebral Palsy: Results from a Pilot Study

The pilot study assessed the utility of a training program using modified, commercially available dual-joystick-operated ride-on toys to promote unimanual and bimanual upper extremity (UE) function in children with cerebral palsy (CP). The ride-on-toy training was integrated within a 3-week, intensive, task-oriented training camp for children with CP. Eleven children with hemiplegia between 4 and 10 years received the ride-on-toy training program 20-30 min/day, 5 days/week for 3 weeks. Unimanual motor function was assessed using the Quality of Upper Extremity Skills Test (QUEST) before and after the camp. During ride-on-toy training sessions, children wore activity monitors on both wrists to assess the duration and intensity of bimanual UE activity. Video data from early and late sessions were coded for bimanual UE use, independent navigation, and movement bouts. Children improved their total and subscale QUEST scores from pretest to post-test while increasing moderate activity in their affected UE from early to late sessions, demonstrating more equal use of both UEs across sessions. There were no significant changes in the rates of movement bouts from early to late sessions. We can conclude that joystick-operated ride-on toys function as child-friendly, intrinsically rewarding tools that can complement conventional therapy and promote bimanual motor functions in children with CP.

Investigation of in-phase bilateral exercise effects on corticospinal plasticity in relapsing remitting multiple sclerosis: A registered report single-case concurrent multiple baseline design across five subjects

Relapsing-remitting Multiple Sclerosis is the most common demyelinating neurodegenerative disease and is characterized by periods of relapses and generation of various motor symptoms. These symptoms are associated with the corticospinal tract integrity, which is quantified by means of corticospinal plasticity which can be probed via transcranial magnetic stimulation and assessed with corticospinal excitability measures. Several factors, such as exercise and interlimb coordination, can influence corticospinal plasticity. Previous work in healthy and in chronic stroke survivors showed that the greatest improvement in corticospinal plasticity occurred during in-phase bilateral exercises of the upper limbs. During in-phase bilateral movement, both upper limbs are moving simultaneously, activating the same muscle groups and triggering the same brain region respectively. Altered corticospinal plasticity due to bilateral cortical lesions is common in MS, yet, the impact of these type of exercises in this cohort is unclear. The aim of this concurrent multiple baseline design study is to investigate the effects of in-phase bilateral exercises on corticospinal plasticity and on clinical measures using transcranial magnetic stimulation and standardized clinical assessment in five people with relapsing-remitting MS. The intervention protocol will last for 12 consecutive weeks (30-60 minutes /session x 3 sessions/week) and include in-phase bilateral movements of the upper limbs, adapted to different sports activities and to functional training. To define functional relation between the intervention and the results on corticospinal plasticity (central motor conduction time, resting motor threshold, motor evoked potential amplitude and latency) and on clinical measures (balance, gait, bilateral hand dexterity and strength, cognitive function), we will perform a visual analysis and if there is a potential sizeable effect, we will perform statistical analysis. A possible effect from our study, will introduce a proof-of-concept for this type of exercise that will be effective during disease progression. Trial registration: ClinicalTrials.gov NCT05367947.

Motor learning and tDCS: A systematic review on the dependency of the stimulation effect on motor task characteristics or tDCS assembly specifications

TDCS is one of the most commonly used methods among studies with transcranial electrical stimulation and motor skills learning. Differences between study results suggest that the effect of tDCS on motor learning is dependent on the motor task performed or on the tDCS assembly specification used in the learning process. This systematic review aimed to analyze the tDCS effect on motor learning and verify whether this effect is dependent on the task or tDCS assembly specifications. Searches were performed in PubMed, SciELO, LILACS, Web of Science, CINAHL, Scopus, SPORTDiscus, Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and PsycINFO. Articles were included that analyzed the effect of tDCS on motor learning through pre-practice, post-practice, retention, and/or transfer tests (period ≥24 h). The tDCS was most frequently applied to the primary motor cortex (M1) or the cerebellar cortex (CC) and the majority of studies found significant stimulation effects. Studies that analyzed identical or similar motor tasks show divergent results for the tDCS effect, even when the assembly specifications are the same. The tDCS effect is not dependent on motor task characteristics or tDCS assembly specifications alone but is dependent on the interaction between these factors. This interaction occurs between uni and bimanual tasks with anodal uni and bihemispheric (bilateral) stimulations at M1 or with anodal unihemispheric stimulations (unilateral and centrally) at CC, and between tasks of greater or lesser difficulty with single or multiple tDCS sessions. Movement time seems to be more sensitive than errors to indicate the effects of tDCS on motor learning, and a sufficient amount of motor practice to reach the "learning plateau" also seems to determine the effect of tDCS on motor learning.

A Robotic System to Deliver Multiple Physically Bimanual Tasks via Varying Force Fields

Individuals with physical limb disabilities are often restricted to perform activities of daily life (ADLs). While efficacy of bilateral training has been demonstrated in improving physical coordination of human limbs, few robots have been developed in simulating people's ADLs integrated with task-specific force field control. This study sought to develop a bilateral robot for better task rendering of general ADLs (gADLs), where gADL-consistent workspace is achieved by setting linear motors in series, and haptic rendering of multiple bimanual tasks (coupled, uncoupled and semi-coupled) is enabled by regulating force fields between robotic handles. Experiments were conducted with human users, and our results present a viable method of a single robotic system in simulating multiple physically bimanual tasks. In future, the proposed robotic system is expected to be serving as a coordination training device, and its clinical efficacy will be also investigated.

The effect of acute aerobic exercise on the consolidation of motor memories

Acute aerobic exercise performed prior to training may assist with motor skill acquisition through enhancement of motor cortical plasticity. In addition, high-intensity exercise performed after training improves retention, although the mechanisms of this are unclear. We hypothesized that acute continuous moderate-intensity exercise performed post-motor training would also assist with motor skill retention and that this behavioral change would be positively correlated with neural markers of training-related cortical adaptation. Participants [n = 33; assigned to an exercise (EXE) or control (CON) group] completed a single visuomotor training session using bilateral wrist movements while movement-related cortical potentials (MRCPs) were collected. After motor training, the EXE group exercised for 20 min [70% of heart rate reserve (HRR)] and the CON group read for the same amount of time. Both groups completed two post-training tests after exercise/rest: 10 min and ~ 30 min once heart rate returned to resting level in EXE. Retention and transfer tests were both completed 1 and 7 days later. MRCPs measured training-related neural adaptations during the first visit and motor performance was assessed as time and trajectory to the target. The EXE group had better performance than CON at retention (significant 7 days post-training). MRCP amplitudes increased from early to late motor training and this amplitude change was correlated with motor performance at retention. Results suggest that moderate-intensity exercise post-motor training helps motor skill retention and that there may be a relationship with motor training-related cortical adaptations that is enhanced with post-motor training exercise.

The Effect of Parietal and Cerebellar Transcranial Direct Current Stimulation on Bimanual Coordinated Adaptive Motor Learning

Abstract. Many daily activities, such as typing, eating, playing the piano, and passing the ball in volleyball, require the proficient coordination of both hands. In this study, the effects of anodal transcranial direct current stimulation (atDCS) on the acquisition, retention, and transfer of bimanual adaptive motor tasks were investigated. To this end, 64 volunteers ( Mage = 24.36 years; SD = 2.51; 16 females) participated in this double-blind study and were categorized randomly into 4 groups. During the pretest, posttest, 24-h and 48-h retention, and transfer tests, two forms of bimanual coordination (BC) of the Vienna test system were performed. Between the pretest and posttest, all participants were trained in a bimanual coordination adaptive task with concurrent brain stimulation (1.5 mA for 15 min) for two consecutive days. The first experimental group (parietal-stim) received atDCS over the right parietal cortex (P4), while the second experimental group (cerebellar-stim) received atDCS over the bilateral cerebellum (2.5 cm bilateral to the inion). The third group (sham) received a sham stimulation. Finally, the control group did not receive any stimulation at all (control). Repeated-measure analysis of variance (ANOVARM) results indicated that parietal tDCS affected motor performance in the posttest, while overall mean duration and overall error mean duration of movement decreased. The results also revealed a significant impact of cerebellar tDCS on the posttest, 24-h and 48-h retention, and transfer tests. The overall mean duration and overall error mean durations of movement in this group were significantly lower than those in the other groups. Accordingly, we found evidence that atDCS over the cerebellum leads to more improvement in motor performance and transfer in a bimanual coordination task than atDCS over the right parietal. Finally, these results point to the possibly beneficial application of atDCS for learning and recovery of bimanual motor skills, especially when subjects are faced with a new challenging situation.

Musical mirror-symmetrical movement tasks: comparison of rhythm versus melody-playing

Bimanual mirror-symmetrical movement (MSM) is relatively easy to control movement. Different MSM tasks may have different activations and interhemispheric interactions. The purpose of this study is to compare anatomo-physiological features such as hemispheric activations and dominance of two different MSMs, namely melody-playing and rhythm. We examined functional MRI (fMRI) recordings in a group of fifteen right-handed pianists performing two separate tasks: bimanual rhythm and bimanual melody-playing on two different keyboards with standard key order for right hand and reversed for left hand, which allows homolog fingers' movements. Activations and laterality indices on fMRI were examined. The results show that significant cerebellar activations (especially in anterior cerebellum) in both groups. Significant primary sensorimotor cortical activations are observed in the melody-playing group. While there are also bilaterally symmetric activations, and laterality indices suggest overall lateralization towards the left hemisphere in both groups. Activations in the left fronto-parietal cortex, left putamen and left thalamus in conjunction with right cerebellar activations suggest that the left cortico-thalamo-cerebellar loop may be a dominant loop. Dynamic causal modeling (DCM) indicates the presence of causal influences from the left to the right cerebral cortex. In conclusion, melody-playing with bimanual MSM is a complex in-phase task and may help activate the bilateral cortical areas, and left hemisphere is dominant according to laterality indices and DCM results. On the other hand, bimanual rhythm is a simpler in-phase task and may help activate subcortical areas, which might be independent of the voluntary cortical task.

Effectiveness of bimanual coordination tasks performance in improving coordination skills and cognitive functions in elderly

Background

The purpose of the study was to determine the impact of the performance of bimanual coordination tasks with specific characteristics on the changes in quality of coordination, musculoskeletal load of the upper limbs and cognitive functions.

Methods and findings

A group of 26 people aged 60–67 years performed 6 sessions of bimanual coordination training. Each session included set of tasks that varied depending on the shape in which the cursor moved, the coordination mode (in-phase, anti-phase, complex) and the tracking mode (imposed or freely chosen speed). Performance was assessed by: Error, Variability and Execution. The load of upper limb muscles was expressed with the value of the normalized EMG amplitude. Cognitive functions were evaluated using the Vienna Test System. The Variability and Error values obtained during the sixth training session decreased by more than 50% of the initial values. Tasks with freely chosen speed showed changes from 15% to 34% for Error and from 45% to 50% for Variability. For tasks with imposed speed and coordination mode anti-phase or complex it was between 51% and 58% for Error and between 58% and 68% for Variability. Statistically significant differences between load during the sixth training session compared to the first session occurred in three out of four muscles and were between 9% to 39%. There were statistically significant differences in motor time and no differences in variables describing attention and working memory.

Conclusions

Coordination mode is meaningful for improving coordination skills; tasks in the anti-phase and complex are recommended. Tracking mode also plays a role, tasks with an imposed cursor movement speed have greater potential to improve coordination skills than tasks with freely chosen. Improved control skills resulted in the reduction of upper limb musculoskeletal load. It can be assumed that an increase in coordination skills with the use of appropriate training can help to reduce musculoskeletal load.

Brain Oscillatory and Hemodynamic Activity in a Bimanual Coordination Task Following Transcranial Alternating Current Stimulation (tACS): A Combined EEG-fNIRS Study

Motor control is associated with synchronized oscillatory activity at alpha (8–12 Hz) and beta (12–30 Hz) frequencies in a cerebello-thalamo-cortical network. Previous studies demonstrated that transcranial alternating current stimulation (tACS) is capable of entraining ongoing oscillatory activity while also modulating motor control. However, the modulatory effects of tACS on both motor control and its underlying electro- and neurophysiological mechanisms remain ambiguous. Thus, the purpose of this study was to contribute to gathering neurophysiological knowledge regarding tACS effects by investigating the after-effects of 10 Hz tACS and 20 Hz tACS at parietal brain areas on bimanual coordination and its concurrent oscillatory and hemodynamic activity. Twenty-four right-handed healthy volunteers (12 females) aged between 18 and 30 (M = 22.35 ± 3.62) participated in the study and performed a coordination task requiring bimanual movements. Concurrent to bimanual motor training, participants received either 10 Hz tACS, 20 Hz tACS or a sham stimulation over the parietal cortex (at P3/P4 electrode positions) for 20 min via small gel electrodes (3,14 cm² Ag/AgCl, amperage = 1 mA). Before and three time-points after tACS (immediately, 30 min and 1 day), bimanual coordination performance was assessed. Oscillatory activities were measured by electroencephalography (EEG) and hemodynamic changes were examined using functional near-infrared spectroscopy (fNIRS). Improvements of bimanual coordination performance were not differently between groups, thus, no tACS-specific effect on bimanual coordination performance emerged. However, physiological measures during the task revealed significant increases in parietal alpha activity immediately following 10 Hz tACS and 20 Hz tACS which were accompanied by significant decreases of Hboxy concentration in the right hemispheric motor cortex compared to the sham group. Based on the physiological responses, we conclude that tACS applied at parietal brain areas provoked electrophysiological and hemodynamic changes at brain regions of the motor network which are relevant for bimanual motor behavior. The existence of neurophysiological alterations immediately following tACS, especially in the absence of behavioral effects, are elementary for a profound understanding of the mechanisms underlying tACS. The lack of behavioral modifications strengthens the need for further research on tACS effects on neurophysiology and behavior using combined electrophysiological and neuroimaging methods.

Effects of High-Definition Anodal Transcranial Direct Current Stimulation Applied Simultaneously to Both Primary Motor Cortices on Bimanual Sensorimotor Performance

Many daily activities, such as tying one’s shoe laces, opening a jar of jam or performing a free throw in basketball, require the skillful coordinated use of both hands. Even though the non-invasive method of transcranial direct current stimulation (tDCS) has been repeatedly shown to improve unimanual motor performance, little is known about its effects on bimanual motor performance. More knowledge about how tDCS may improve bimanual behavior would be relevant to motor recovery, e.g., in persons with bilateral impairment of hand function. We therefore examined the impact of high-definition anodal tDCS (HD-atDCS) on the performance of a bimanual sequential sensorimotor task. Thirty-two volunteers (age M = 24.25; SD = 2.75; 14 females) participated in this double-blind study and performed sport stacking in six experimental sessions. In sport stacking, 12 specially designed cups must be stacked (stacked up) and dismantled (stacked down) in predefined patterns as fast as possible. During a pretest, posttest and follow-up test, two sport stacking formations (3-6-3 stack and 1-10-1 stack) were performed. Between the pretest and posttest, all participants were trained in sport stacking with concurrent brain stimulation for three consecutive days. The experimental group (STIM-M1) received HD-atDCS over both primary motor cortices (M1), while the control group received a sham stimulation (SHAM). Three-way analysis of variance (ANOVA) revealed a significant main effect of TIME and a significant interaction of TIME × GROUP. No significant effects were found for GROUP, nor for the three-way interaction of TIME × GROUP × FORMATION. Further two-way ANOVAs showed a significant main effect of TIME and a non-significant main effect for GROUP in both sport stacking formations. A significant interaction between TIME × GROUP was found only for the 3-6-3 formation, indicating superior performance gains for the experimental group (STIM-M1). To account and control for baseline influences on the outcome measurements, ANCOVAs treating pretest scores as covariates revealed a significant effect of the stimulation. From this, we conclude that bilateral HD-atDCS over both M1 improves motor performance in a bimanual sequential sensorimotor task. These results may indicate a beneficial use of tDCS for learning and recovery of bimanual motor skills.

Coupled Bimanual Training Using a Non-Powered Device for Individuals with Severe Hemiparesis: A Pilot Study

BACKGROUND

Few options exist for training arm movements in participants with severe post-stroke hemiparesis who have little active range of motion. The purpose of this study was to test the safety and feasibility of training with a non-powered device, the Bimanual Arm Trainer (BAT), to facilitate motor recovery in individuals with severe hemiparesis. The BAT enabled coupled bimanual training of shoulder external rotation, which is reduced in individuals with severe post-stroke hemiplegia. The rationale for bimanual training was to harness contralesional cortical activity to drive voluntary movement in the affected arm in patients who could barely perform unimanual movements.

METHODS

Nine participants with post-stroke hemiparesis, preserved passive range of motion and Modified Ashworth score of <3 in the shoulder and elbow joints, trained with the device for 45 minutes, twice a week for six weeks, and were assessed pre- and post-training.

RESULTS

All participants tolerated the training and no adverse events were reported. Participants showed significant improvement in the upper extremity Fugl-Meyer score post-training with an effect size of 0.89. Changes in the flexor synergy pattern accounted for 64.7% of the improvement. Improvement in active range of motion in the paretic limb occurred for both trained and untrained movements. Some participants showed improvement in the time taken to perform selected tasks on the Wolf Motor Function Test post-training.

CONCLUSION

The results demonstrate the safety and feasibility of using the Bimanual Arm Trainer to facilitate motor recovery in individuals with severe hemiparesis.

Does Corticospinal Tract Connectivity Influence the Response to Intensive Bimanual Therapy in Children With Unilateral Cerebral Palsy?

BACKGROUND

Reorganization of the corticospinal tract (CST) can occur in unilateral spastic cerebral palsy (USCP). The affected hand can be controlled via (1) typical contralateral projections from the lesioned hemisphere, (2) ipsilateral projections from the nonlesioned hemisphere, and (3) a combination of contralateral and ipsilateral projections (ie, bilateral). Intensive bimanual therapy and constraint-induced movement therapy (CIMT) improve hand function of children with USCP. Earlier it was suggested that the CST connectivity pattern may influence the efficacy of CIMT.

OBJECTIVE

To examine whether CST projection pattern influences the efficacy of intensive bimanual therapy in children with USCP.

PARTICIPANTS

Thirty-three children with USCP (age 8.9 ± 2.6 years, 16 females).

METHODS

Bimanual therapy was provided in a day-camp setting (90 hours). Participants were involved in different bimanual play and functional activities actively engaging both hands. Hand function was tested before and after the intervention with the Jebsen-Taylor Test of Hand Function, Assisting Hand Assessment, ABILHAND-Kids, and the Canadian Occupational Performance Measure. Single-pulse transcranial magnetic stimulation (TMS) was used to determine each child's CST projection pattern (ie, ipsilateral, contralateral, or bilateral).

RESULTS

Children whose affected hand was controlled only by ipsilateral CST projections had worse Jebsen-Taylor Test of Hand Function and Assisting Hand Assessment scores than children in the contralateral group at baseline. Bimanual hand use and functional hand use was independent of CST projection pattern. After bimanual therapy, improvements on all outcome measures were observed, and these improvements were independent of the CST connectivity pattern.

CONCLUSION

The efficacy of bimanual therapy on hand function in children with USCP appears to be independent of CST connectivity pattern.

Aerobic exercise enhances neural correlates of motor skill learning

INTRODUCTION

Repetitive, in-phase bimanual motor training tasks can expand the excitable cortical area of the trained muscles. Recent evidence suggests that an acute bout of moderate-intensity aerobic exercise can enhance the induction of rapid motor plasticity at the motor hotspot. However, these changes have not been investigated throughout the entire cortical representation. Furthermore, it is unclear how exercise-induced changes in excitability may relate to motor performance. We investigated whether aerobic exercise could enhance the neural correlates of motor learning. We hypothesized that the combination of exercise and training would increase the excitable cortical area to a greater extent than either exercise or training alone, and that the addition of exercise would enhance performance on a motor training task.

METHODS

25 young, healthy, right-handed individuals were recruited and divided into two groups and three experimental conditions. The exercise group performed exercise alone (EX) and exercise followed by training (EXTR) while the training group performed training alone (TR).

RESULTS

The combination of exercise and training increased excitability within the cortical map of the trained muscle to a greater extent than training alone. However, there was no difference in performance between the two groups. These results indicate that exercise may enhance the cortical adaptations to motor skill learning.

Effect of auditory constraints on motor performance depends on stage of recovery post-stroke

In order to develop evidence-based rehabilitation protocols post-stroke, one must first reconcile the vast heterogeneity in the post-stroke population and develop protocols to facilitate motor learning in the various subgroups. The main purpose of this study is to show that auditory constraints interact with the stage of recovery post-stroke to influence motor learning. We characterized the stages of upper limb recovery using task-based kinematic measures in 20 subjects with chronic hemiparesis. We used a bimanual wrist extension task, performed with a custom-made wrist trainer, to facilitate learning of wrist extension in the paretic hand under four auditory conditions: (1) without auditory cueing; (2) to non-musical happy sounds; (3) to self-selected music; and (4) to a metronome beat set at a comfortable tempo. Two bimanual trials (15 s each) were followed by one unimanual trial with the paretic hand over six cycles under each condition. Clinical metrics, wrist and arm kinematics, and electromyographic activity were recorded. Hierarchical cluster analysis with the Mahalanobis metric based on baseline speed and extent of wrist movement stratified subjects into three distinct groups, which reflected their stage of recovery: spastic paresis, spastic co-contraction, and minimal paresis. In spastic paresis, the metronome beat increased wrist extension, but also increased muscle co-activation across the wrist. In contrast, in spastic co-contraction, no auditory stimulation increased wrist extension and reduced co-activation. In minimal paresis, wrist extension did not improve under any condition. The results suggest that auditory task constraints interact with stage of recovery during motor learning after stroke, perhaps due to recruitment of distinct neural substrates over the course of recovery. The findings advance our understanding of the mechanisms of progression of motor recovery and lay the foundation for personalized treatment algorithms post-stroke.