Bimanual Task Research Articles

Assessment of gamified mixed reality environments for upper limb robotic rehabilitation: pilot study on healthy adults

Exoskeletons for rehabilitation have the potential to aid movement and promote intensive, task-oriented, and personalized motor training. However, robotic-assisted training and user experience could be further improve by including Mixed Reality Environments (MREs) and using a gamification approach. This paper presents the design and evaluation of a MR solution based on Microsoft Hololens 2 for robot-assisted bilateral shoulder training. It is based on gamified MREs designed to guide and encourage bilateral synchronous and asynchronous movements of the upper extremities while a 6 Degrees of Freedom (DOF) exoskeleton (FLOAT) provides motor assistance only to the impared limb. The robotic-assisted bimanual tasks involve the use of rehabilitative tools (such as a dowel rod), as a means to interact with the virtual world and to enable the intact limb guide and control the motions of the disable limb. The gamified MR training solution generates meaningful performance metrics from the kinematic analysis of hands movement, captured by Hololens. The subjective evaluation of the gamified MR solution focused on usability, cognitive load, and user experience. Meanwhile, the objective evaluation encompassed the analysis of the robot-assisted movements with and without gamified MREs, a comparative analysis between metrics obtained from Hololens and Vicon data, and the collection of reference data and trajectories. There were twenty-one healthy adults involved in the evaluation of the system. The results with the gamified MREs highlight excellent system usability, low cognitive load, and high user experience. Additionally, integrating gamified MREs into robot-assisted movements enhances shoulder movements. Data collection with Hololens demonstrated to be reliable and consistent. Furthermore, the normal reference values, paths, and velocity profiles obtained from healthy individuals offer a foundation for assessing the performance of individuals with disabilities. In summary, the introduction of gamified MREs for robot-assisted bilateral shoulder movements marks a significant and promising advancement in rehabilitation technology.

Investigating the impact of mental rehearsal on prefrontal and motor cortical haemodynamic responses in surgeons using optical neuroimaging.

Inadequate exposure to real-life operating can impede timely acquisition of technical competence among surgical residents, and is a major challenge faced in the current training climate. Mental rehearsal (MR)-the cognitive rehearsal of a motor task without overt physical movement-has been shown to accelerate surgical skills learning. However, the neuroplastic effect of MR of a complex bimanual surgical task is unknown. The aim of this study is to use functional near-infrared spectroscopy (fNIRS) to assess the impact of MR on prefrontal and motor cortical activation during a laparoscopic knot tying task. Twelve surgical residents performed a laparoscopic knot tying task before and after either mental rehearsal (MR, intervention group) or textbook reading (TR, control group). In both groups, fNIRS was used to measure changes in oxygenated hemoglobin concentration (HbO2) in the prefrontal (24 channels) and motor cortices (22 channels). Technical performance was measured using leak volume, objective performance score and task progression score. MR led to a decrease in HbO2 (reduced activation) in the bilateral prefrontal cortex (PFC), and an increase in HbO2 (increased activation) in the left middle frontal gyrus, left precentral gyrus, and left postcentral gyrus. No discernible changes in activation were observed after TR in either the PFC or motor cortex. Moreover, smaller ΔHbO2 responses in the right PFC and greater ΔHbO2 responses in the left motor cortex were observed in the MR group compared with the TR group. Leak volume was significantly less following MR (p = 0.019), but not after TR (p = 0.347). Mean objective performance score was significantly higher following MR compared with TR (p = 0.043). Mental rehearsal may enhance surgical skill acquisition and technical proficiency by reducing utilization of attentional resources in the prefrontal cortex and improving neural efficiency in motor areas during a laparoscopic surgical task.

Brain imaging and clinical outcome of embodied VR-BCI training in chronic stroke patients: a longitudinal pilot study

ABSTRACT Introduction Restorative Brain–Computer Interfaces (BCIs) provide an alternative non-muscular channel for stroke patients lacking volitional movement by enhancing sensorimotor rhythm modulation through motor imagery (MI). MI practice can be augmented with embodied feedback via virtual reality (VR). However, the clinical impact of embodied VR-BCI training remains under-explored. Methods This study examines the effects of embodied VR-BCI training on brain activity patterns (measured through EEG and fMRI) and clinical outcomes (assessed by the Fugl–Meyer Assessment, FMA) in four chronic stroke patients. Over a 3-week MI-BCI intervention, patients performed a bimanual rowing task (NeuRow) in VR. EEG data were used to extract Event-related desynchronization (ERD) and lateralization indices, while fMRI data focused on the primary motor (M1) and supplementary motor (SMA) regions of interest. Results Results indicated that all patients significantly induced ERD power, though the affected side exhibited reduced ERD compared to baseline during contralateral MI. Post-intervention, significant ERD differences from both hemispheres were observed, with decreased ERD correlating with no clinical improvement. Patients showing decreased ERD lateralization had no FMA score improvement. Activity within ipsilesional M1 and SMA correlated with FMA scores. Conclusions The findings suggest a relationship between brain activity and clinical outcomes, highlighting that increased ERD lateralization is associated with clinical improvement.

Spatiotemporal coordination in children with unilateral cerebral palsy: Insights from a bimanual goal-directed task

BackgroundIn children with unilateral cerebral palsy (uCP), bimanual assessments mostly focus on qualitative assessments of the impaired upper limb during bimanual tasks, which do not capture the spatiotemporal coordination between both hands. Hence, we aimed to advance our understandings in spatiotemporal coordination in children with uCP compared to typically developing children (TDC) using a bimanual, asymmetrical, goal-directed task. Participants and methodologyIn this observational study, thirty-seven children with uCP (11y8m±2y10m, 20 males, 16 right-sided uCP, Manual Ability Classification System level I = 23, II = 11, III = 3) and 37 age and sex-matched TDC opened a box with one hand and pressed a button inside using the opposite hand. Spatiotemporal bimanual (movement time, temporal coupling, movement overlap, goal synchronisation) and unimanual (movement time, path length and smoothness) parameters were extracted. Between groups comparisons were investigated using a two-way mixed ANCOVA with age as covariate (α < 0.05). Additionally, correlation coefficients between unimanual and bimanual parameters were calculated. ResultsCompared to TDC, children with uCP were slower (p = 0.01, ηp2 = 0.13) and presented unimanual spatiotemporal deficits in both upper limbs (p < 0.03, ηp2>0.10), which worsened in children with lower manual abilities (p < 0.04, ηp2>0.19). However, they did not differ in bimanual coupling (p > 0.31, ηp2<0.03). Furthermore, slower movement time was related with increased unimanual spatiotemporal deficits bilaterally (r = 0.34–0.80, p = 0.001–0.04), suggesting that reduced performance at both upper limbs contributes to bimanual difficulties in children with uCP. ConclusionsThe bilateral reduced spatiotemporal performance, related to longer bimanual movement time, stresses the importance to assess and treat both upper limbs in children with uCP.

Kernels of Motor Memory Formation: Temporal Generalization in Bimanual Adaptation.

In daily life, we coordinate both simultaneous and sequential bimanual movements to manipulate objects. Our ability to rapidly account for different object dynamics suggests there are neural mechanisms to quickly deal with them. Here we investigate how actions of one arm can serve as a contextual cue for the other arm, and facilitate adaptation. Specifically, we examine the temporal characteristics that underlie motor memory formation and recall, by testing the contextual effects of prior, simultaneous, and post contralateral arm movements in both male and female human participants. To do so, we measure their temporal generalization in three bimanual interference tasks. Importantly, the timing context of the learned action plays a pivotal role in the temporal generalization. While motor memories trained with post adaptation contextual movements generalize broadly, motor memories trained with prior contextual movements exhibit limited generalization, and motor memories trained with simultaneous contextual movements do not generalize to prior or post contextual timings. This highlights temporal tuning in sensorimotor plasticity: different training conditions yield substantially different temporal generalization characteristics. Since these generalizations extend far beyond any variability in training times, we suggest that the observed differences may stem from inherent differences in the use of prior, current and post-adaptation contextual information in the generation of natural behavior. This would imply differences in the underlying neural circuitry involved in learning and executing the corresponding coordinated bimanual movements.Significance Statement This study addresses a fundamental question in the field of sensorimotor neuroscience of how multiple movements are temporally linked within a single motor memory. We examine the temporal generalization of motor memory formation by varying the timing of contextual movements associated with a learned motor memory across a range of prior, current, and post adaptation movement times using a bimanual motor learning task. We observed distinct patterns of temporal generalization based on whether the contextual movements occurred prior to, simultaneously with, or after the adaptation movement. For the first time, our findings reveal that the timing of contextual movements is crucial in the formation and generalization of motor memories.

BLUE SABINO: Development of a BiLateral Upper-Limb Exoskeleton for Simultaneous Assessment of Biomechanical and Neuromuscular Output

Arm and hand function play a critical role in the successful completion of everyday tasks. Lost function due to neurological impairment impacts millions of lives worldwide. Despite improvements in the ability to assess and rehabilitate arm deficits, knowledge about underlying sources of impairment and related sequela remains limited. The comprehensive assessment of function requires the measurement of both biomechanics and neuromuscular contributors to performance during the completion of tasks that often use multiple joints and span three-dimensional workspaces. To our knowledge, the complexity of movement and diversity of measures required are beyond the capabilities of existing assessment systems. To bridge current gaps in assessment capability, a new exoskeleton instrument is developed with comprehensive bilateral assessment in mind. The development of the BiLateral Upper-limb Exoskeleton for Simultaneous Assessment of Biomechanical and Neuromuscular Output (BLUE SABINO) expands on prior iterations toward full-arm assessment during reach-and-grasp tasks through the development of a dual-arm and dual-hand system, with 9 active degrees of freedom per arm and 12 degrees of freedom (six active, six passive) per hand. Joints are powered by electric motors driven by a real-time control system with input from force and force/torque sensors located at all attachment points between the user and exoskeleton. Biosignals from electromyography and electroencephalography can be simultaneously measured to provide insight into neurological performance during unimanual or bimanual tasks involving arm reach and grasp. Design trade-offs achieve near-human performance in exoskeleton speed and strength, with positional measurement at the wrist having an error of less than 2 mm and supporting a range of motion approximately equivalent to the 50th-percentile human. The system adjustability in seat height, shoulder width, arm length, and orthosis width accommodate subjects from approximately the 5th-percentile female to the 95th-percentile male. Integration between precision actuation, human–robot-interaction force-torque sensing, and biosignal acquisition systems successfully provide the simultaneous measurement of human movement and neurological function. The bilateral design enables use with left- or right-side impairments as well as intra-subject performance comparisons. With the resulting instrument, the authors plan to investigate underlying neural and physiological correlates of arm function, impairment, learning, and recovery.

Analyses of the impact of laterality on performances in the National Hockey League based on players’ position and origin

This study addresses the question of the lateral preference of the National Hockey League players. The shooting preference, left or right, was analysed as a function of the origin of four groups of players that are from the USA, Canada, Europe, or Russia. The analysis reveals that the players from the USA are more likely to shoot right than players from other countries. Also, compared to defense players from other groups, defense players from the USA have a higher number of shots per game and a higher goal-to-assist ratio. The study also shows that for wingers shooting left, those playing on the right wing have more goals or points per game than those playing on the left wing; and that European forward players have a better differential (+/−) than American and Canadian forward players. The study reveals the influence of the players’ origin on the preference in a bimanual asymmetric task and the impact of this preference on ice hockey performances.

Magic-themed motor training on daily bimanual task performance in children with unilateral spastic cerebral palsy: A systematic review and meta-analysis.

Magic-themed motor training on daily bimanual task performance in children with unilateral spastic cerebral palsy: A systematic review and meta-analysis.

The real magic of magic therapy: Improving daily bimanual task performance in children with unilateral spastic cerebral palsy.

The real magic of magic therapy: Improving daily bimanual task performance in children with unilateral spastic cerebral palsy.

Bimanual Coordination in Children with Bilateral Cerebral Palsy: A Cross-Sectional Study

Aim To compare bimanual coordination in children with bilateral cerebral palsy (BCP) with that of children with typical development (TD) and correlate bimanual coordination with clinical measures of hand function. Methods 3-D kinematic data were collected from 14 children with BCP (mean age 13 years 1 month; range 7.3–17.2 years, 5 females) and 14 age-matched children with TD (mean age 13 years 1 month, range 7.0–16.0 years, 7 females) as they opened a drawer with one hand and activated a switch inside it with the other hand at self-paced and as-fast-as-possible speeds. Hand roles varied in each condition. Participants' hand function levels were classified using the Manual Ability Classification System. Unimanual dexterity and bimanual performance were evaluated using the Box and Blocks Test and Both Hands Assessment respectively. Results Participants with BCP performed the bimanual task more slowly (p < 0.001) and sequentially, as evidenced by greater time differences between the two hands achieving the end goal (p = 0.01). Faster speeds, particularly when the less affected hand opened the drawer, facilitated time-related measures of bimanual coordination (p < 0.05). Bimanual coordination correlated with all clinical measures of hand function (p < 0.05). Conclusion For children with BCP, speed and hand used for each subcomponent of the task influence bimanual coordination. Better bimanual coordination is associated with less impairment of both hands.

Toward methodologies for motor imagery enhancement: a tDCS-BCI study

ABSTRACT Motor imagery (MI) becomes a powerful rehabilitation tool, particularly when combined with brain–computer interfaces (BCI). Therefore, methods to improve MI accuracy are a trending topic in the BCI field. Here, we examined the effects of transcranial direct current stimulation (tDCS) and MI priming on the MI signature in an EEG-based MI-BCI triple-blind study. Thirty healthy younger adults participated in this study and were designated to one of two priming groups: A bimanual tracking task and a MI task as primers for MI-BCI. During the performance of the primer task, participants received anodal and sham tDCS in two randomized sessions with a one-week wash-out period between sessions. Subsequently, participants performed an EEG-driven BCI-MI task. EEG time–frequency analyses revealed that desynchronization of the Beta Region precedes desynchronization in the Alpha Region, implying that the Beta frequency band might be best-suited to extract MI signatures as it could lead to faster MI-BCI. Contrary to our hypotheses, no effect of tDCS or priming task on EEG activity during the BCI-MI task was found. Future research should carefully consider the added value of tDCS and priming tasks BCI performance improvement. Electric field modeling studies and high-definition tDCS motor cortex stimulation might be promising avenues.

Motor cortex activation mediates associations between striatal dopamine depletion and manual dexterity in Parkinson's disease

IntroductionParkinson's disease (PD) presents with a progressive decline in manual dexterity, attributed to dysfunction in the basal ganglia-thalamus-cortex loop, influenced by dopaminergic deficits in the striatum. Recent research suggests that the motor cortex may play a pivotal role in mediating the relationship between striatal dopamine depletion and motor function in PD. Understanding this connection is crucial for comprehending the origins of manual dexterity impairments in PD. Therefore, our study aimed to explore how motor cortex activation mediates the association between striatal dopamine depletion and manual dexterity in PD. Materials and methodsWe enrolled 26 mildly affected PD patients in their off-medication phase to undergo [18F]FDOPA PET/CT scans for evaluating striatal dopaminergic function. EEG recordings were conducted during bimanual anti-phase finger tapping tasks to evaluate motor cortex activity, specifically focusing on Event-Related Desynchronization in the beta band. Manual dexterity was assessed using the Purdue Pegboard Test. Regression-based mediation analysis was conducted to examine whether motor cortex activation mediates the association between striatal dopamine depletion and manual dexterity in PD. ResultsMediation analysis revealed a significant direct effect of putamen dopamine depletion on manual dexterity for the affected hand and assembly tasks (performed with two hands), with motor cortex activity mediating this association. In contrast, while caudate nucleus dopamine depletion showed a significant direct effect on manual dexterity, motor cortex mediation on this association was not observed. ConclusionOur study confirms the association between striatum dopamine depletion and impaired manual dexterity in PD, with motor cortex activity mediating this relationship.

Force Fluctuations During Role-Differentiated Bimanual Movements Reflect Cognitive Impairments in Older Adults: A Cohort Sequential Study.

During role-differentiated bimanual movements (RDBM), an object is typically stabilized with 1 hand and manipulated with the other. RDBM require coupling both hands for coordinated action (achieved through interhemispheric connections), but also inhibition of crosstalk to avoid involuntary movements in the stabilizing hand. We investigated how healthy cognitive aging and mild cognitive impairments (MCI) affect force stabilization during an RDBM in a cohort sequential study design with up to 4 measurement points over 32 months. In total, 132 older adults (>80 years) participated in this study, 77 were cognitively healthy individuals (CHI) and 55 presented with MCI. Participants performed a visuomotor bimanual force-tracking task. They either produced a constant force with both hands (bimanual constant) or a constant force with 1 and an alternating force with the other hand (role-differentiated). We investigated force fluctuations of constant force production using the coefficient of variation (CV), detrended fluctuation analysis (DFA), and sample entropy (SEn). Results showed higher CV and less complex variability structure (higher DFA and lower SEn) during the role-differentiated compared to the bimanual constant task. Furthermore, CHI displayed a more complex variability structure during the bimanual constant, but a less complex structure during the role-differentiated task than MCI. Interestingly, this complexity reduction was more pronounced in CHI than MCI individuals, suggesting different changes in the control mechanisms. Although understanding these changes requires further research, potential causes might be structural deteriorations leading to less efficient (intra- and interhemispheric) networks because of MCI, or an inability to appropriately divert the focus of attention.

Bimanual coordinated motor skill learning in patients with a chronic cerebellar stroke.

Cerebellar strokes induce coordination disorders that can affect activities of daily living. Evidence-based neurorehabilitation programs are founded on motor learning principles. The cerebellum is a key neural structure in motor learning. It is unknown whether and how well chronic cerebellar stroke individuals (CCSIs) can learn to coordinate their upper limbs through bimanual motor skill learning. The aim was to determine whether CCSIs could achieve bimanual skill learning through a serious game with the REAplan® robot and to compare CCSIs with healthy individuals (HIs). Over three consecutive days, sixteen CCSIs and eighteen HIs were trained on an asymmetric bimanual coordination task ("CIRCUIT" game) with the REAplan® robot, allowing quantification of speed, accuracy and coordination. The primary outcomes were the bimanual speed/accuracy trade-off (BiSAT) and bimanual coordination factor (BiCo). They were also evaluated on a bimanual REACHING task on Days 1 and 3. Correlation analyses between the robotic outcomes and clinical scale scores were computed. Throughout the sessions, BiSAT and BiCo improved during the CIRCUIT task in both HIs and CCSIs. On Day 3, HIs and CCSIs showed generalization of BiSAT, BiCo and transferred to the REACHING task. There was no significant between-group difference in progression. Four CCSIs and two HIs were categorized as "poor learners" according to BiSAT and/or BiCo. Increasing age correlated with reduced BiSAT but not BiCo progression. Over three days of training, HIs and CCSIs improved, retained, generalized and transferred a coordinated bimanual skill. There was no between-group difference, suggesting plastic compensation in CCSIs. Clinical trial NCT04642599 approved the 24th of November 2020.

Filtering walking actigraphy data in children with unilateral cerebral palsy: A preliminary study.

This study aimed to determine whether filtering out walking-related actigraphy data improves the reliability and accuracy of real-world upper extremity activity assessment in children with unilateral cerebral palsy. Twenty-two children aged 4-12 years diagnosed with unilateral cerebral palsy were included in this study, which was drawn from a two-phase randomized controlled trial conducted from July 2021 to December 2022. Data were collected from a tertiary hospital in Seoul, Republic of Korea. Participants were monitored using tri-axial accelerometers on both wrists across three time points (namely, T0, T1, and T2) over 3 days; interventions were used between each time point. Concurrently, an in-laboratory study focusing on walking and bimanual tasks was conducted with four participants. Data filtration resulted in a reduction of 8.20% in total data entry. With respect to reliability assessment, the intra-class correlation coefficients indicated enhanced consistency after filtration, with increased values for both the affected and less-affected sides. Before filtration, the magnitude counts for both sides showed varying tendencies, depending on the time points; however, they presented a consistent and stable trend after filtration. The findings of this research underscore the importance of accurately interpreting actigraphy measurements in children with unilateral cerebral palsy for targeted upper limb intervention by filtering walking-induced data.

Bi-DexHands: Towards Human-Level Bimanual Dexterous Manipulation.

Achieving human-level dexterity in robotics remains a critical open problem. Even simple dexterous manipulation tasks pose significant difficulties due to the high number of degrees of freedom and the need for cooperation among heterogeneous agents (e.g., finger joints). While some researchers have utilized reinforcement learning (RL) to control a single hand in manipulating objects, tasks that require coordinated bimanual cooperation are still under-explored due to the fewer suitable environments, which can result in difficulties and sub-optimal performance. To address these challenges, we introduce Bi-DexHands, a simulator with two dexterous hands featuring 20 bimanual manipulation tasks and thousands of target objects, designed to match various levels of human motor skills based on cognitive science research. We developed Bi-DexHands in Issac Gym, enabling highly efficient RL training at over 30,000 frames per second using a single NVIDIA RTX 3090. Based on Bi-DexHands, we present a comprehensive evaluation of popular RL algorithms in different settings, including single-agent/multi-agent RL, offline RL, multi-task RL, and meta RL. Our findings show that on-policy algorithms, such as PPO, can master simple manipulation tasks that correspond to those of 48-month-old babies, such as catching a flying object or opening a bottle. Furthermore, multi-agent RL can improve the ability to perform manipulations that require skilled bimanual cooperation, such as lifting a pot or stacking blocks. Despite achieving success in individual tasks, current RL algorithms struggle to learn multiple manipulation skills in most multi-task and few-shot learning scenarios. This highlights the need for further research and development within the RL community.

Excitatory/inhibitory motor balance reflects individual differences during joint action coordination.

Joint action (JA) is a continuous process of motor co-regulation based on the integration of contextual (top-down) and kinematic (bottom-up) cues from partners. The fine equilibrium between excitation and inhibition in sensorimotor circuits is, thus, central to such a dynamic process of action selection and execution. In a bimanual task adapted to become a unimanual JA task, the participant held a bottle (JA), while a confederate had to reach and unscrew either that bottle or another stabilized by a mechanical clamp (No_JA). Prior knowledge was manipulated in each trial such that the participant knew (K) or not (No_K) the target bottle in advance. Online transcranial magnetic stimulation (TMS) was administered at action-relevant landmarks to explore corticospinal excitability (CSE) and inhibition (cortical silent period [cSP]). CSE was modulated early on before the action started if prior information was available. In contrast, cSP modulation emerged later during the reaching action, regardless of prior information. These two indexes could thus reflect the concurrent elaboration of contextual priors (top-down) and the online sampling of partner's kinematic cues (bottom-up). Furthermore, participants selected either one of two possible behavioural strategies, preferring early or late force exertion on the bottle. One translates into a reduced risk of motor coordination failure and the other into reduced metabolic expenditure. Each strategy was characterised by a specific excitatory/inhibitory profile. In conclusion, the study of excitatory/inhibitory balance paves the way for the neurophysiological determination of individual differences in the combination of top-down and bottom-up processing during JA coordination.

Older and younger adults differ in time course of skill acquisition but not in overall improvement in a bimanual visuomotor tracking task.

Manual motor performance declines with age, but the extent to which age influences the acquisition of new skills remains a topic of debate. Here, we examined whether older healthy adults show less training-dependent performance improvements during a single session of a bimanual pinch task than younger adults. We also explored whether physical and cognitive factors, such as grip strength or motor-cognitive ability, are associated with performance improvements. Healthy younger (n = 16) and older (n = 20) adults performed three training blocks separated by short breaks. Participants were tasked with producing visually instructed changes in pinch force using their right and left thumb and index fingers. Task complexity was varied by shifting between bimanual mirror-symmetric and inverse-asymmetric changes in pinch force. Older adults generally displayed higher visuomotor force tracking errors during the more complex inverse-asymmetric task compared to younger adults. Both groups showed a comparable net decrease in visuomotor force tracking error over the entire session, but their improvement trajectories differed. Young adults showed enhanced visuomotor tracking error only in the first block, while older adults exhibited a more gradual improvement over the three training blocks. Furthermore, grip strength and performance on a motor-cognitive test battery scaled positively with individual performance improvements during the first block in both age groups. Together, the results show subtle age-dependent differences in the rate of bimanual visuomotor skill acquisition, while overall short-term learning ability is maintained.

Learning to Assist Bimanual Teleoperation Using Interval Type-2 Polynomial Fuzzy Inference

Assisting humans in collaborative tasks is a promising application for robots, however effective assistance remains challenging. In this paper, we propose a method for providing intuitive robotic assistance based on learning from human natural limb coordination. To encode coupling between multiple-limb motions, we use a novel interval type-2 (IT2) polynomial fuzzy inference for modeling trajectory adaptation. The associated polynomial coefficients are estimated using a modified recursive least-square with a dynamic forgetting factor. We propose to employ a Gaussian process to produce robust human motion predictions, and thus address the uncertainty and measurement noise of the system caused by interactive environments. Experimental results on two types of interaction tasks demonstrate the effectiveness of this approach, which achieves high accuracy in predicting assistive limb motion and enables humans to perform bimanual tasks using only one limb.

Effect of Transcranial Alternating Current Stimulation on Motor Performance

Transcranial alternating current stimulation (tACS) is a non-invasive method of brain stimulation that can modulate oscillatory brain activity in the cortical region. By applying alternating current through two electrodes attached to a subject’s head, it is possible to entrain the oscillation of the cortex directly under one electrode to a specific frequency. This study finds that applying tACS to the primary motor cortex and cerebellar hemisphere improves motor performance. The study also shows the effect of tACS on the supplementary motor cortex to modulate the maintenance and update of motor plans in a bimanual motor task. These recent findings show that individualized tACS interventions can be tailored by selecting the stimulation area and frequency depending on the subject’s performance level and exercise task. By further investigating the effects of tACS on motor performance, it is believed that tACS can be applied in rehabilitation.