Bidirectional locomotion induces unilateral limb adaptations.

Humans can acquire and maintain motor skills throughout their lives through motor learning. Motor learning and skill acquisition are essential for rehabilitation following neurological disease or injury. Adaptation, the initial stage of motor learning, involves short-term changes in motor performance in response to a new demand in the person's environment. Repeated adaptation can improve skill performance and result in long-term skill retention. Locomotor adaptation is extensively studied using split-belt treadmill paradigms. In this study we explored whether bidirectional walking (BDW) on a split-belt treadmill can induce short-term gait adaptations. Twelve healthy volunteers participated in our single session, starting with 2 minutes of normal walking (NW), followed by four 5-minute blocks of BDW with a 1-minute passive rest in between blocks, and ending with another 2-minute of NW. We recorded body kinematics and ground reaction forces throughout the experiment. Participants quickly adapted to BDW with both legs showing decreased step lengths. However, only the backward-walking leg exhibited aftereffects upon returning to NW, indicating short-term adaptation. Notable kinematic changes were observed, particularly in hip extension and pelvis tilt, though these varied among participants. Our findings suggest that BDW induces unilateral adaptations despite bilateral changes in gait, offering new insights into locomotor control and spinal CPG organization.

An overview of the effects and mechanisms of transcranial stimulation frequency on motor learning.

Many studies over the recent decades have attempted the modulation of motor learning using brain stimulation. Alternating currents allow for researchers not only to electrically stimulate the brain, but to further investigate the effects of specific frequencies, in and beyond the context of their endogenous associations. Transcranial alternating current stimulation (tACS) has therefore been used during motor learning to modulate aspects of acquisition, consolidation and performance of a learned motor skill. Despite numerous reviews on the effects of tACS, and its role in motor learning, there are few studies which synthesize the numerous frequencies and their respective theoretical mechanisms as they relate to motor and perceptual processes. Here we provide a short overview of the main stimulation frequencies used in motor learning modulation (e.g., alpha, beta, and gamma), and discuss the effect and proposed mechanisms of these studies. We summarize with the current state of the field, the effectiveness and variability in motor learning modulation, and novel mechanistic proposals from other fields.

Differential effects of theta-gamma tACS on motor skill acquisition in young individuals and stroke survivors: A double-blind, randomized, sham-controlled study.

BACKGROUND: Theta-gamma transcranial alternating current stimulation (tACS) was recently found to enhance thumb acceleration in young, healthy participants, suggesting a potential role in facilitating motor skill acquisition. Given the relevance of motor skill acquisition in stroke rehabilitation, theta-gamma tACS may hold potential for treating stroke survivors. OBJECTIVE: We aimed to examine the effects of theta-gamma tACS on motor skill acquisition in young, healthy participants and stroke survivors. METHODS: In a pre-registered, double-blind, randomized, sham-controlled study, 78 young, healthy participants received either theta-gamma peak-coupled (TGP) tACS, theta-gamma trough-coupled (TGT) tACS or sham stimulation. 20 individuals with a chronic stroke received either TGP or sham. TACS was applied over motor cortical areas while participants performed an acceleration-dependent thumb movement task. Stroke survivors were characterized using standardized testing, with a subgroup receiving additional structural brain imaging. RESULTS: Neither TGP nor TGT tACS significantly modified general motor skill acquisition in the young, healthy cohort. In contrast, in the stroke cohort, TGP diminished motor skill acquisition compared to sham. Exploratory analyses revealed that, independent of general motor skill acquisition, healthy participants receiving TGP or TGT exhibited greater peak thumb acceleration than those receiving sham. CONCLUSION: Although theta-gamma tACS increased thumb acceleration in young, healthy participants, consistent with previous reports, it did not enhance overall motor skill acquisition in a more complex motor task. Furthermore, it even had detrimental effects on motor skill acquisition in stroke survivors.

Comparison of short- and long-term effects of neurofeedback and transcranial electrical stimulation on the motor learning in healthy adults.

Researchers are exploring non-invasive neuromodulation techniques like transcranial direct current stimulation (tDCS) and neurofeedback (NFB) for enhancing motor learning. While tDCS modulates brain excitability using exogenous electric fields, NFB is an endogenous brain stimulation technique that enables individuals to regulate brain excitability in a closed-loop system. Despite their differing mechanisms, a direct comparison of their effects on motor learning is lacking. This study aimed to compare tDCS and NFB on online learning, short-term offline learning, and long-term offline learning in healthy participants, seeking to identify the most effective method for motor learning enhancement. In this parallel, randomized, single-blinded, controlled trial, 100 healthy participants were randomly assigned to one of five groups: real tDCS, sham tDCS, real NFB, sham NFB, and passive control. Primary outcomes included normalized reaction time (NRT), normalized response accuracy (NRA), and normalized skill index (NSI), measured through a serial reaction time task. Secondary outcomes involved physical and mental fatigue, assessed using a visual analog scale. The study involved 14 blocks of 80 trials each. Online learning was assessed by changes in NRT, NRA, and NSI between Block 3 and Block 9. Short-term and long-term offline learning were evaluated by changes in these measures between Block 9 and Block 11, and between Block 9 and Block 13, respectively. RESULTS: showed a significant decrease in NRA in the sham tDCS and passive control groups from block 3-9, with no changes in other groups. NRT significantly decreased in all intervention groups from block 9-11, with no change in the control group. The NSI significantly increased across all intervention groups between blocks 9 and 11, with large to very large effect sizes, while the passive control group saw a medium effect size increase. Furthermore, NRA significantly increased in the real NFB and real tDCS groups from block 9 to block 13. NRT also significantly decreased in all intervention groups when comparing block 13 to block 9, while the passive control group showed no significant changes. Notably, the reduction in NRT from block 9 to block 13 was significantly greater in the real tDCS group than in the control group, with a mean difference of 0.087 (95 % CI: 0.004-0.169, p = 0.031). Additionally, NSI significantly increased in all intervention groups except the control group from block 9 to block 13. In conclusion, neither NFB nor tDCS had a significant positive impact on online learning. However, both real and sham versions of tDCS and NFB resulted in notable improvements in short-term offline learning. The difference in improvement between NFB and tDCS, as well as between real and sham interventions, was not statistically significant, suggesting that the placebo effect may play a significant role in enhancing short-term offline learning. For long-term offline learning, both brain stimulation methods, particularly tDCS, showed positive effects, although the placebo effect also appeared to contribute.

Task-dependent coarticulation of movement sequences.

Combining individual actions into sequences is a hallmark of everyday activities. Classical theories propose that the motor system forms a single specification of the sequence as a whole, leading to the coarticulation of the different elements. In contrast, recent neural recordings challenge this idea and suggest independent execution of each element specified separately. Here, we show that separate or coarticulated sequences can result from the same task-dependent controller, without implying different representations in the brain. Simulations show that planning for multiple reaches simultaneously allows separate or coarticulated sequences depending on instructions about intermediate goals. Human experiments in a two-reach sequence task validated this model. Furthermore, in co-articulated sequences, the second goal influenced long-latency stretch responses to external loads applied during the first reach, demonstrating the involvement of the sensorimotor network supporting fast feedback control. Overall, our study establishes a computational framework for sequence production that highlights the importance of feedback control in this essential motor skill.

Assessing and Enhancing Movement Quality Using Wearables and Consumer Technologies: Thematic Analysis of Expert Perspectives.

BACKGROUND: Improvements in movement quality (ie, how well an individual moves) facilitate increases in movement quantity, subsequently improving general health and quality of life. Wearable technology offers a convenient, affordable means of measuring and assessing movement quality for the general population, while technology more broadly can provide constructive feedback through various modalities. Considering the perspectives of professionals involved in the development and implementation of technology helps translate user needs into effective strategies for the optimal application of consumer technologies to enhance movement quality. OBJECTIVE: This study aimed to obtain the opinions of wearable technology experts regarding the use of wearable devices to measure movement quality and provide feedback. A secondary objective was to determine potential strategies for integrating preferred assessment and feedback characteristics into a technology-based movement quality intervention for the general, recreationally active population. METHODS: Semistructured interviews were conducted with 12 participants (age: mean 42, SD 9 years; 5 males) between August and September 2022 using a predetermined interview schedule. Participants were categorized based on their professional roles: commercial (n=4) and research and development (R&D; n=8). All participants had experience in the development or application of wearable technology for sports, exercise, and wellness. The verbatim interview transcripts were analyzed using reflexive thematic analysis in QSR NVivo (release 1.7), resulting in the identification of overarching themes and subthemes. RESULTS: Three main themes were generated as follows: (1) "Grab and Go," (2) "Adjust and Adapt," and (3) "Visualize and Feedback." Participants emphasized the importance of convenience to enhance user engagement when using wearables to collect movement data. However, it was suggested that users would tolerate minor inconveniences if the benefits were perceived as valuable. Simple, easily interpretable feedback was recommended to accommodate diverse audiences and aid understanding of their movement quality, while avoiding excessive detail was advised to prevent overload, which could deter users. Adaptability was endorsed to accommodate progressions in user movement quality, and customizable systems were advocated to offer variety, thereby increasing user interest and engagement. The findings indicate that visual feedback representative of the user (ie, an avatar) should be used, supplemented with concise text or audible instructions to form a comprehensive, multimodal feedback system. CONCLUSIONS: The study provides insights from wearable technology experts on the use of consumer technologies for enhancing movement quality. The findings recommend the prioritization of user convenience and simplistic, multimodal feedback centered around visualizations, and an adaptable system suitable for a diverse audience. Emphasizing individualized feedback and user-centric design, this study provides valuable findings around the use of wearables and other consumer technologies to enhance movement quality among the general population. These findings, in conjunction with those of future research into user perspectives, should be applied in practical settings to evaluate their effectiveness in enhancing movement quality.

Motor Learning in a Complex Motor Task Is Unaffected by Three Consecutive Days of Transcranial Alternating Current Stimulation.

Transcranial alternating current stimulation (tACS) delivered to the primary motor cortex (M1) can increase cortical excitability, entrain neuronal firing patterns, and increase motor skill acquisition in simple motor tasks. The primary aim of this study was to assess the impact of tACS applied to M1 over three consecutive days of practice on the motor learning of a challenging overhand throwing task in young adults. The secondary aim was to examine the influence of tACS on M1 excitability. This study implemented a double-blind, randomized, SHAM-controlled, between-subjects experimental design. A total of 24 healthy young adults were divided into tACS and SHAM groups and performed three identical experimental sessions that comprised blocks of overhand throwing trials of the right dominant arm concurrent with application of tACS to the left M1. Performance in the overhand throwing task was quantified as the endpoint error. Motor evoked potentials (MEPs) were assessed in the right first dorsal interosseus (FDI) muscle with transcranial magnetic stimulation (TMS) to quantify changes in M1 excitability. Endpoint error was significantly decreased in the post-tests compared with the pre-tests when averaged over the three days of practice (p = 0.046), but this decrease was not statistically significant between the tACS and SHAM groups (p = 0.474). MEP amplitudes increased from the pre-tests to the post-tests (p = 0.003), but these increases were also not different between groups (p = 0.409). Overall, the main findings indicated that tACS applied to M1 over multiple days does not enhance motor learning in a complex task to a greater degree than practice alone (SHAM).

Influence of sleep on motor skill acquisition in children: a systematic review.

Effects of sleep on procedural (implicit) memory consolidation in children remain controversial. The aim of this systematic review was to synthesise the evidence on the influence of sleep on motor skills acquisition in children. Four electronic databases were searched: PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Excerpta Medica Database (Embase), and Biblioteca Virtual em Saúde (BVS). Original studies, published until October 17, 2023, on motor skill acquisition in children aged ≤12 years, in which the intervention group slept after motor skill training, while the control group remained awake, were considered for inclusion. Risk of bias was evaluated using the Cochrane's Risk of Bias 2 tool. The review protocol was pre-registered at the International Prospective Register of Systematic Reviews (PROSPERO protocol number: CRD42022363868) and all reported items followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Of the 7241 articles initially retrieved, nine met the primary criteria and were included in this review. Of these, six studies reported that daytime or night-time sleep intervention improved motor skill acquisition, as compared to wakefulness. All studies presented a high risk of bias. In conclusion, the evidence summarised suggests that sleep may enhance motor skills acquisition and could be important for motor development in childhood. However, due to the high risk of bias in the included studies, future randomised controlled trials with high methodological quality are necessary to better clarify this topic.

Acceptability and Feasibility of Portable Eye-Tracking Technology within a Children's Dynamic Sport Context: An Exploratory Study with Boys Who Play Grassroots Football.

Teaching practices are moving from decontextualised to more representative curricula. Although this is argued to be a positive step, low motor competence is a continual issue in primary-aged school children. One methodological approach to investigate ways to improve motor competence, eye tracking, is moving to more representative tasks. So far, eye-tracking research using static activities has demonstrated a positive association between motor competence and earlier fixation and longer duration. However, this research has been constrained to laboratory settings and tasks, or discrete activities (e.g., throw and catch). This study seeks to understand how to conduct more representative eye-tracking research in primary school-aged children. To this end, thirteen 10-11-year-old children were fitted with an eye-tracker during a typical football coaching session. Children were asked acceptability-based questions, and eye-gaze data were captured to illustrate what children attended to under a representative dynamic football-based activity. Based on the voices of children and captured eye-gaze data, six practical implications for research in this population are proposed: (1) conduct eye-tracking research indoors (where possible); (2) ensure long hair or fringes are secured so as not to obscure line of sight; (3) run the same activity to increase comparability across children wearing the eye-tracker; (4) use a properly fitted backpack (if a backpack is to be used); (5) assure children about the capability and hardiness of the eye-tracker, as they do not need to change the way they move; (6) explain there may be some discomfort with the nose clip, head strap, and battery weight and ensure that children wish to continue.

Non-Dominant Hemisphere Excitability Is Unaffected during and after Transcranial Direct Current Stimulation of the Dominant Hemisphere.

Transcranial direct current stimulation (tDCS) increases primary motor cortex (M1) excitability and improves motor performance when applied unilaterally to the dominant hemisphere. However, the influence of tDCS on contralateral M1 excitability both during and after application has not been quantified. The purpose was to determine the influence of tDCS applied to the dominant M1 on the excitability of the contralateral non-dominant M1. This study employed a double-blind, randomized, SHAM-controlled, within-subject crossover experimental design. Eighteen young adults performed two experimental sessions (tDCS, SHAM) in counterbalanced order separated by a one-week washout. Transcranial magnetic stimulation (TMS) was used to quantify the excitability of the contralateral M1 to which anodal tDCS was applied for 20 min with a current strength of 1 mA. Motor evoked potential (MEP) amplitudes were assessed in 5 TMS test blocks (Pre, D5, D10, D15, and Post). The Pre and Post TMS test blocks were performed immediately before and after tDCS application, whereas the TMS test blocks performed during tDCS were completed at the 5, 10, and 15 min stimulation timepoints. MEPs were analyzed with a 2 condition (tDCS, SHAM) × 5 test (Pre, D5, D10, D15, Post) within-subject ANOVA. The main effect for condition (p = 0.213), the main effect for test (p = 0.502), and the condition × test interaction (p = 0.860) were all not statistically significant. These results indicate that tDCS does not modulate contralateral M1 excitability during or immediately after application, at least under the current set of common tDCS parameters of stimulation.

Two Physiotherapy Methods to Improve the Physical Condition of Children with Autism Spectrum Disorder.

This study presents two simple physiotherapy programs that were implemented for five weeks and showed positive changes in balance, coordination, and motor skills in kindergarteners with ASD. Physiotherapy programs in a gym and games on a smart board with balance plates and an unstable base were applied to improve the physical condition of children with ASD. Thirty children with ASD (4-6 years old) attending special needs kindergarten were enrolled in the study. Three tests were used to assess participants' physical condition before and after the study: the modified Berg Balance Scale, the Imbalance Coordination Sample, and the Bruininks-Oseretsky Motor Proficiency Test (BOTMP). The resulting mean change, calculated from each group's scores, shows that the participants who received physical therapy sessions at the smart board had the greatest change of 1.58 points. It shows that the opportunity to play games on a smart board motivates children with ASD to work harder; therefore, it is a simple and easy way to engage children in different types of physical exercise. A slightly smaller change of 1.51 was obtained in the group that received gym sessions. However, working in the gym was more psychologically challenging for the children with ASD due to their lack of desire and motivation. Both methods are relatively simple and easy to apply at home; therefore, parents can make a significant contribution to improving children's physical condition and that can be an effective tool to assist these individuals with activities in daily life.

Construct Validity of the Athlete Introductory Movement Screen in Grassroots Footballers Aged 11-13 Years.

BACKGROUND: This study examined the construct validity of the Athlete Introductory Movement Screen (AIMS) in children. METHODS: Following ethics approval, parental consent, and child assent, 87 children (50 boys, 37 girls) aged 11-13 years (Mean ± SD = 12.4 ± 0.6 years) performed the AIMS and Test of Gross Motor Development (TGMD-3) in a counterbalanced order. AIMS tertiles were subsequently created, classifying children with 'high', 'medium', or 'low' movement skills. RESULTS: A 2 (Gender) X 3 (AIMS tertile) ways analysis of covariance (ANCOVA), controlling for age and age at peak height velocity, with TGMD-3 scores as the dependant variable, indicated that TGMD-3 scores were significantly higher for girls categorised as having a medium movement skill compared to girls categorised as low, and those categorised having high movement skill compared to medium and low movement skill groups (all, p = 0.001). There was no difference in TGMD-3 scores for boys classed as having low and medium movement skills. Boys categorised as high for movement skills had significantly greater TGMD-3 scores than their peers categorised as having both low and medium movement skills (p = 0.001). CONCLUSIONS: As the AIMS differentiates the theoretically related construct of motor competence, this study demonstrates that the AIMS has construct validity as a measure of movement skill in children aged 11-13 years.

The effects of reward and punishment on the performance of ping-pong ball bouncing.

Introduction: Reward and punishment modulate behavior. In real-world motor skill learning, reward and punishment have been found to have dissociable effects on optimizing motor skill learning, but the scientific basis for these effects is largely unknown. Methods: In the present study, we investigated the effects of reward and punishment on the performance of real-world motor skill learning. Specifically, three groups of participants were trained and tested on a ping-pong ball bouncing task for three consecutive days. The training and testing sessions were identical across the three days: participants were trained with their right (dominant) hand each day under conditions of either reward, punishment, or a neutral control condition (neither). Before and after the training session, all participants were tested with their right and left hands without any feedback. Results: We found that punishment promoted early learning, while reward promoted late learning. Reward facilitated short-term memory, while punishment impaired long-term memory. Both reward and punishment interfered with long-term memory gains. Interestingly, the effects of reward and punishment transferred to the left hand. Discussion: The results show that reward and punishment have different effects on real-world motor skill learning. The effects change with training and transfer readily to novel contexts. The results suggest that reward and punishment may act on different learning processes and engage different neural mechanisms during real-world motor skill learning. In addition, high-level metacognitive processes may be enabled by the additional reinforcement feedback during real-world motor skill learning. Our findings provide new insights into the mechanisms underlying motor learning, and may have important implications for practical applications such as sports training and motor rehabilitation.

Reliability of the Test of Gross Motor Development Third Edition Among Children with Developmental Coordination Disorder.

AIM: The Test of Gross Motor Development Third Edition (TGMD-3) is used to assess the development of fundamental movement skills in children from 3 to 10 years old. This study aimed to evaluate the intra-rater, inter-rater, and test-retest reliability and to determine the minimal detectable change (MDC) value of the TGMD-3 in children with developmental coordination disorder (DCD). METHODS: The TGMD-3 was administered to 20 children with DCD. The child's fundamental movement skills were recorded using a digital video camera. Reliability was assessed at two occasions by three raters using the generalizability theory. RESULTS: The TGMD-3 demonstrates good inter-rater reliability for the locomotor skills subscale, the ball skills subscale, and the total score (φ = 0.77 - 0.91), while the intra-rater reliability was even higher (φ = 0.94 - 0.97). Test-retest reliability was also shown to be good (φ = 0.79-0.93). The MDC95 was determined to be 10 points. CONCLUSION: This study provides evidence that the TGMD-3 is a reliable test when used to evaluate fundamental movement skills in children with DCD and suggests that an increase of 10 points represents a significant change in the motor function of a child with DCD.

Complex decongestive therapy improves finger tapping score in patients with breast cancer-related lymphedema.

PURPOSE: Breast cancer-related lymphedema (BCRL) impairs upper limb function and cognitive performance. This study aimed to evaluate the effects of fifteen sessions of complex decongestive therapy (CDT) on fine motor performance and information processing speed in women with BCRL. METHODS: Thirty-eight women with BCRL (54.97 ± 10.78 years) were recruited in the study. Participants either received five times weekly CDT consisting of manual lymphatic drainage, skin care, compression bandaging, and remedial exercises (n = 19) or served as a wait-list control group (n = 19). We used the Finger Tapping Task to assess fine motor performance and the Digit Symbol Substitution Test to assess information processing speed. ANCOVA was performed to analyze the effect of CDT on the dependent variables, adjusting for covariates and baseline values. RESULTS: CDT significantly improved finger tapping score (p < 0.001) compared to the wait-list to the control group, whereas information processing speed did not significantly change (p = 0.673). CONCLUSION: The findings suggest that CDT is an effective conservative therapeutic approach to improve upper extremity fine motor function in women with BCRL. Future studies are needed to investigate the effect of CDT on different cognitive domains.

Combining motor imagery practice with physical practice optimizes the improvement in peak force control during thoracic spinal manipulation.

Spinal manipulation learning requires intensive practice, which can cause injuries in students. Motor imagery (MI) paired with physical practice (PP) appears to be a suitable means to reduce the number of physical repetitions without decreasing skill outcomes. This study examines whether a session of MI paired with PP leads to a similar improvement in the ability to precisely produce peak forces during a thoracic manipulation as PP alone. Chiropractic students participated in a thoracic manipulation training program for five weeks. They were randomised in two groups: the MI+PP group performed sessions combining physical and mental repetitions with 1/3 fewer PP sessions, while the PP group performed only PP. Thoracic manipulation performance was assessed in pre and post-tests, consisting of thoracic manipulations at three different strength targets. Absolute error (AE), corresponding to the difference between the force required and the force applied by the student, was recorded for each trial. The main result revealed that AE was significantly lower in post-test than in pre-test for both groups. Despite fewer physical repetitions, the MI+PP participants showed as much improvement as the PP participants. This result supports the use of MI combined with PP to optimise the benefits of physical repetitions on thoracic manipulation learning.

La combinaison de la pratique de l'imagerie motrice avec la pratique physique optimise l'amélioration du contrôle de la force maximale pendant la manipulation vertébrale thoracique.L'apprentissage de la manipulation vertébrale nécessite une pratique intensive qui peut entraîner des blessures chez les étudiants. L'imagerie motrice (IM) associée à la pratique physique (PP) semble être un moyen approprié pour réduire le nombre de répétitions physiques sans diminuer les acquis de compétences. Cette étude examine de quelle manière une séance d'IM combinée à la pratique physique entraîne une amélioration similaire pour doser avec précision leur force lors d'une manipulation thoracique par rapport à la pratique physique seule. Des étudiants en chiropratique ont participé à un programme de formation à la manipulation thoracique pendant cinq semaines. Ils ont été répartis au hasard en deux groupes: le groupe IM + PP a effectué des séances combinant des répétitions physiques et mentales avec 1/3 de séances PP en moins, tandis que le groupe PP n'a effectué que des séances PP. Les résultats des manipulations thoraciques ont été évalués lors de prétests et de post-tests, consistant en des manipulations thoraciques à trois niveaux de force différents. L'erreur absolue (EA), correspondant à la différence entre la force requise et la force appliquée par l'étudiant, a été enregistrée pour chaque essai. Le résultat principal a révélé que l'EA était significativement plus faible dans le post-test que dans le pré-test pour les deux groupes. Malgré un nombre inférieur de répétitions physiques, les participants IM+PP ont montré autant d'amélioration que les participants PP. Ce résultat soutient l'utilisation de l'IM combinée à la PP pour optimiser les avantages des répétitions physiques sur l'apprentissage de la manipulation thoracique.

Alternative muscle synergy patterns of upper limb amputees.

Myoelectric hand prostheses are effective tools for upper limb amputees to regain hand functions. Much progress has been made with pattern recognition algorithms to recognize surface electromyography (sEMG) patterns, but few attentions was placed on the amputees' motor learning process. Many potential myoelectric prostheses users could not fully master the control or had declined performance over time. It is possible that learning to produce distinct and consistent muscle activation patterns with the residual limb could help amputees better control the myoelectric prosthesis. In this study, we observed longitudinal effect of motor skill learning with 2 amputees who have developed alternative muscle activation patterns in response to the same set of target prosthetic actions. During a 10-week program, amputee participants were trained to produce distinct and constant muscle activations with visual feedback of live sEMG and without interaction with prosthesis. At the end, their sEMG patterns were different from each other and from non-amputee control groups. For certain intended hand motion, gradually reducing root mean square (RMS) variance was observed. The learning effect was also assessed with a CNN-LSTM mixture classifier designed for mobile sEMG pattern recognition. The classification accuracy had a rising trend over time, implicating potential performance improvement of myoelectric prosthesis control. A follow-up session took place 6 months after the program and showed lasting effect of the motor skill learning in terms of sEMG pattern classification accuracy. The results indicated that with proper feedback training, amputees could learn unique muscle activation patterns that allow them to trigger intended prosthesis functions, and the original motor control scheme is updated. The effect of such motor skill learning could help to improve myoelectric prosthetic control performance.

Reduced inhibitory synaptic transmission onto striatopallidal neurons may underlie aging-related motor skill deficits.

Human beings are living longer than ever before and aging is accompanied by an increased incidence of motor deficits, including those associated with the neurodegenerative conditions, Parkinson's disease (PD) and Huntington's disease (HD). However, the biological correlates underlying this epidemiological finding, especially the functional basis at the synapse level, have been elusive. This study reveals that motor skill performance examined via rotarod, beam walking and pole tests is impaired in aged mice. This study, via electrophysiology recordings, further identifies an aging-related reduction in the efficacy of inhibitory synaptic transmission onto dorsolateral striatum (DLS) indirect-pathway medium spiny neurons (iMSNs), i.e., a disinhibition effect on DLS iMSNs. In addition, pharmacologically enhancing the activity of DLS iMSNs by infusing an adenosine A2A receptor (A2AR) agonist, which presumably mimics the disinhibition effect, impairs motor skill performance in young mice, simulating the behavior in aged naïve mice. Conversely, pharmacologically suppressing the activity of DLS iMSNs by infusing an A2AR antagonist, in order to offset the disinhibition effect, restores motor skill performance in aged mice, mimicking the behavior in young naïve mice. In conclusion, this study identifies a functional inhibitory synaptic plasticity in DLS iMSNs that likely contributes to the aging-related motor skill deficits, which would potentially serve as a striatal synaptic basis underlying age being a prominent risk factor for neurodegenerative motor deficits.

The Effects of Motionless Interventions Based on Visual-Auditory Instructions With Sonification on Learning a Rhythmic Motor Skill.

Our aim in this study was to investigate the effects of motionless interventions, based on visual-auditory integration with a sonification technique, on the learning a complex rhythmic motor skill. We recruited 22 male participants with high physical fitness and provided them four acquisition sessions in which to practice hurdle running, based on a visual-auditory instructional pattern. Next, we divided participants into three groups: visual-auditory, auditory, and control. In six sessions of motionless interventions, with no physical practice, participants in the visual-auditory group received a visual-auditory pattern similar to their experience during the acquisition period. The auditory group only listened to the sound of sonified movements of an expert hurdler, and the control group received no instructional interventions. Finally, participants in all three groups underwent post-intervention and transfer tests to determine their errors in the spatial and relative timing of their leading leg's knee angular displacement. Both visual-auditory and auditory groups had significantly less spatial error than the control group. However, there were no significant group differences in relative timing in any test phase. These results indicate that the use of the sonification technique in the form of visual-auditory instruction adapted to the athletes' needs benefitted perception-sensory capacities to improve motor skill learning.

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.