Facilitate Motor Learning Research Articles

Resting-state functional connectivity and motor imagery brain activation.

Motor imagery (MI) relies on the mental simulation of an action without any overt motor execution (ME), and can facilitate motor learning and enhance the effect of rehabilitation in patients with neurological conditions. While functional magnetic resonance imaging (fMRI) during MI and ME reveals shared cortical representations, the role and functional relevance of the resting-state functional connectivity (RSFC) of brain regions involved in MI is yet unknown. Here, we performed resting-state fMRI followed by fMRI during ME and MI with the dominant hand. We used a behavioral chronometry test to measure ME and MI movement duration and compute an index of performance (IP). Then, we analyzed the voxel-matched correlation between the individual MI parameter estimates and seed-based RSFC maps in the MI network to measure the correspondence between RSFC and MI fMRI activation. We found that inter-individual differences in intrinsic connectivity in the MI network predicted several clusters of activation. Taken together, present findings provide first evidence that RSFC within the MI network is predictive of the activation of MI brain regions, including those associated with behavioral performance, thus suggesting a role for RSFC in obtaining a deeper understanding of neural substrates of MI and of MI ability. Hum Brain Mapp 37:3847-3857, 2016. © 2016 Wiley Periodicals, Inc.

Contextual Interference Can Facilitate Motor Learning in Older Adults and in Individuals With Parkinson's Disease

ABSTRACTIn healthy young adults motor learning is typically improved by practice under conditions of high contextual interference such as that created when a series of skills are practiced in a random sequence. The authors examined whether individuals with Parkinson's disease and age-matched older adults might also benefit from such a learning environment. Participants learned 3 peg placement movements under both random practice and blocked practice schedules. Participants completed free-recall, cued-recall, and transfer tests 1 day and 1 week following practice. During acquisition all learners had shorter movement times (MTs) during blocked than random practice but during retention testing, MTs were shorter if the patterns had been learned with random practice. Fewer errors during free recall following random practice were evident in both groups of learners and MTs to complete a novel transfer task were shorter following random practice. These findings suggest employing a cognitively challenging practice environment might improve motor skill learning in elderly learners and in people with Parkinson's disease.

More Feedback Is Better than Less: Learning a Novel Upper Limb Joint Coordination Pattern with Augmented Auditory Feedback.

Motor learning is a process whereby the acquisition of new skills occurs with practice, and can be influenced by the provision of feedback. An important question is what frequency of feedback facilitates motor learning. The guidance hypothesis assumes that the provision of less augmented feedback is better than more because a learner can use his/her own inherent feedback. However, it is unclear whether this hypothesis holds true for all types of augmented feedback, including for example sonified information about performance. Thus, we aimed to test what frequency of augmented sonified feedback facilitates the motor learning of a novel joint coordination pattern. Twenty healthy volunteers first reached to a target with their arm (baseline phase). We manipulated this baseline kinematic data for each individual to create a novel target joint coordination pattern. Participants then practiced to learn the novel target joint coordination pattern, receiving either feedback on every trial i.e., 100% feedback (n = 10), or every other trial, i.e., 50% feedback (n = 10; acquisition phase). We created a sonification system to provide the feedback. This feedback was a pure tone that varied in intensity in proportion to the error of the performed joint coordination relative to the target pattern. Thus, the auditory feedback contained information about performance in real-time (i.e., “concurrent, knowledge of performance feedback”). Participants performed the novel joint coordination pattern with no-feedback immediately after the acquisition phase (immediate retention phase), and on the next day (delayed retention phase). The root-mean squared error (RMSE) and variable error (VE) of joint coordination were significantly reduced during the acquisition phase in both 100 and 50% feedback groups. There was no significant difference in VE between the groups at immediate and delayed retention phases. However, at both these retention phases, the 100% feedback group showed significantly smaller RMSE than the 50% group. Thus, contrary to the guidance hypothesis, our findings suggest that the provision of more, concurrent knowledge of performance auditory feedback during the acquisition of a novel joint coordination pattern, may result in better skill retention.

Action observation therapy: handle with caution?

This commentary is on the original article by Kirkpatrick et al. on pages 1049–1056 of this issue. Observing the movements of another person activates the mirror neuron system. This network of specialized neurons, that discharge either when performing or observing an action, is mainly distributed in the human premotor and parietal cortex. The mirror neuron network is believed to play an essential role in understanding the actions of others, as well as in our capacity to learn by imitation. Action observation therapy is basically a backdoor approach to improve motor (re)learning, allegedly by tapping directly into the mirror neuron system and activating cortical areas which strongly overlap those involved in movement execution.1 In order to facilitate motor learning, action observation therapy typically relies on repeated phases of observation of goal-directed actions followed by their execution. There is increasing evidence for the efficacy of this method in adults with hemiplegia during the subacute and chronic phases of stroke.2 In their trial, which addresses the efficacy of action observation therapy in children with unilateral cerebral palsy (CP), Kirkpatrick et al.3 demonstrate that there is no added-value of action observation over repetitive motor training, in a home-based, parent-delivered variant of the approach. This contrasts with a previous randomized trial in children with unilateral CP by Sgandurra et al.,4 which had shown significant improvements in bimanual function following more intensive, therapist-delivered, action observation therapy. Are these divergent findings due to differing settings and interventions in both studies, or could there be a more fundamental issue about applying action observation to children with early brain lesions? Kirkpatrick et al.3 adopted a pragmatic approach to intervention delivery. In the action observation group, children were repeatedly provided with the opportunity to imitate the motor tasks shown by their parents; whereas those in the control group repeated identical goal-directed tasks for the same time, without the opportunity to imitate their parents. Both groups improved similarly. In Sgandurra et al.'s4 earlier study children in the action observation group watched videos of the actions they were then expected to perform, while those in the control group watched video-games. The action observation group fared better. If this does indicate an intrinsic value of action observation above observing unrelated actions in improving motor performance, the study by Kirkpatrick et al. seems to show that improvements are similar if the time spent observing a movement is actually used to execute the movement. Can all children with unilateral CP be considered responsive to action observation? Indeed if brain lesions have affected the core circuitry of the mirror neuron network, i.e. the premotor and/or parietal cortex and/or their connections, action observation therapy could prove pointless. A functional magnetic resonance imaging study including 18 children with unilateral CP and either cortical or sub-cortical lesions showed that observation of hand movements engaged the motor observation and execution network, regardless of the degree of motor impairment or lesion localization.1 Consequently, a majority of children with unilateral CP might be expected to respond to action observation. To what degree does the activation of the mirror neuron system, based on movement observation, contribute to consolidate motor programmes? A notable study on professional ballet dancers, who based on their sex were familiar or unfamiliar with performing specific moves, demonstrated that mirror circuits have a pure motor response over and above visual representations of movements.5 Mirror system activity seems to depend on possessing the motor representation for an observed action, or in other words on being familiar with performing the movement. The efficacy of action observation therapy in adults after stroke may rely on the remains of their motor observation and execution networks, constituted through a lifetime of repeated normal motor experiences. Children who have never experienced the competent and normal movement patterns that they observe may not have quite the same ability to mimic activities in their mirror neuron systems. In all studies of action observation therapy for unilateral CP, children watched motor tasks performed by expert models. It may be that a shift towards observing less expert learning models (such as other children or even peers with a similar movement disorder) could provide a larger keyhole into their mirror systems. If for the time being action observation should be used cautiously in children, further research may provide refinements that may considerably increase its ability to tap into the developing mirror neuron system.

The primary motor cortex is associated with learning the absolute, but not relative, timing dimension of a task: A tDCS study

The functional role of the primary motor cortex (M1) in the production of movement parameters, such as length, direction and force, is well known; however, whether M1 is associated with the parametric adjustments in the absolute timing dimension of the task remains unknown. Previous studies have not applied tasks and analyses that could separate the absolute (variant) and relative (invariant) dimensions. We applied transcranial direct current stimulation (tDCS) to M1 before motor practice to facilitate motor learning. A sequential key-pressing task was practiced with two goals: learning the relative timing dimension and learning the absolute timing dimension. All effects of the stimulation of M1 were observed only in the absolute dimension of the task. Mainly, the stimulation was associated with better performance in the transfer test in the absolute dimension. Taken together, our results indicate that M1 is an important area for learning the absolute timing dimension of a motor sequence.

Self-control over combined video feedback and modeling facilitates motor learning

Allowing learners to control the video presentation of knowledge of performance (KP) or an expert model during practice has been shown to facilitate motor learning (Aiken, Fairbrother, & Post, 2012; Wulf, Raupach, & Pfeiffer, 2005). Split-screen replay features now allow for the simultaneous presentation of these modes of instructional support. It is uncertain, however, if such a combination incorporated into a self-control protocol would yield similar benefits seen in earlier self-control studies. Therefore, the purpose of the present study was to examine the effects of self-controlled split-screen replay on the learning of a golf chip shot. Participants completed 60 practice trials, three administrations of the Intrinsic Motivation Inventory, and a questionnaire on day one. Retention and transfer tests and a final motivation inventory were completed on day two. Results revealed significantly higher form and accuracy scores for the self-control group during transfer. The self-control group also had significantly higher scores on the perceived competence subscale, reported requesting feedback mostly after perceived poor trials, and recalled a greater number of critical task features compared to the yoked group. The findings for the performance measures were consistent with previous self-control research.

Neural correlates of unihemispheric and bihemispheric motor cortex stimulation in healthy young adults

Bihemispheric non-invasive motor cortex stimulation has shown promise for facilitating motor learning and recovery after stroke. However, previous studies yielded mixed results that can primarily be attributed to inter-individual variability in response. We therefore aimed at investigating neural correlates of bihemispheric transcranial direct current stimulation (tDCS) effects using multimodal magnetic resonance imaging (MRI). Twenty-four young healthy adults underwent diffusion tensor imaging (DTI), resting state and task-related functional MRI in a randomized sham-controlled, double-blind study using a triple cross-over design. We compared two active stimulation conditions—bihemispheric (or “dual”) and unihemispheric anodal tDCS—with sham tDCS. The anode was placed over the left primary motor cortex in all conditions, and subgroups of responders were defined according to task-related activity in this area while subjects pressed a response button with their right index fingers during a choice reaction time task. Compared to sham, “dual responders” and “anodal responders” were characterized by mean beta value increases of 86±55% and 126±55%, respectively. In line with electrophysiological studies, tDCS effects on motor cortex activation appeared to be highly variable across the group. At rest, dual tDCS caused widespread bihemispheric alterations of functional connectivity, possibly mediating its most striking effect, which consisted of bilateral motor cortex disinhibition during the task-related functional MRI. In contrast, unihemispheric anodal tDCS was characterized by more local modulations of functional motor networks. As in aging and after stroke, the impact of dual tDCS on the motor system in young adults seems to depend on the microstructural status of transcallosal motor tracts as well. In sum, these results shed light on the neural correlates of dual and anodal tDCS effects in young adults and help in explaining the great inter-individual variability in response.

Endurance Exercise as an "Endogenous" Neuro-enhancement Strategy to Facilitate Motor Learning.

Endurance exercise improves cardiovascular and musculoskeletal function and may also increase the information processing capacities of the brain. Animal and human research from the past decade demonstrated widespread exercise effects on brain structure and function at the systems-, cellular-, and molecular level of brain organization. These neurobiological mechanisms may explain the well-established positive influence of exercise on performance in various behavioral domains but also its contribution to improved skill learning and neuroplasticity. With respect to the latter, only few empirical and theoretical studies are available to date. The aim of this review is (i) to summarize the existing neurobiological and behavioral evidence arguing for endurance exercise-induced improvements in motor learning and (ii) to develop hypotheses about the mechanistic link between exercise and improved learning. We identify major knowledge gaps that need to be addressed by future research projects to advance our understanding of how exercise should be organized to optimize motor learning.

A neurocognitive approach to recovery of movement following stroke

Background: Most of the therapeutic and research interest following stroke has been directed toward motor impairments, relegating sensory and cognitive aspects involved in the quality of movement to a secondary role. Despite current neurophysiological advances, there are few studies in physical therapy that include all these aspects in stroke patients.Objectives: The present work aimed to review the involvement of mirror neurons in recovering the quality of post-ictal movement in a physical therapy intervention.Major findings: Neurocognitive Therapeutic Exercise (NTE) is a therapeutic approach that includes observation and motor imagery, among others, as perceptual and cognitive functions that generate experiences and afferent information flows without motor activity. Although this approach has shown to be effective on pain and function in shoulder and knee disorders, there is a paucity of evidence in stroke. NTE considers recovery as a learning process, the movement as a means to know and the body as a surface receptor for information. Aspects such as increasing experience, feedback or mirror neurons’ functions are used to allow movements to be improved quantitatively and qualitatively. This could be achieved through the activation of pre-existing neural patterns before the stroke.Conclusions: The neurocognitive approach represents a novel and safe therapeutic intervention supported by neuroscience research. Its implementation in physical therapy could facilitate motor learning in stroke patients. Nevertheless, further research into cognitive strategies in neurological rehabilitation is required to demonstrate their effectiveness.

Brain state-dependent robotic reaching movement with a multi-joint arm exoskeleton: combining brain-machine interfacing and robotic rehabilitation.

While robot-assisted arm and hand training after stroke allows for intensive task-oriented practice, it has provided only limited additional benefit over dose-matched physiotherapy up to now. These rehabilitation devices are possibly too supportive during the exercises. Neurophysiological signals might be one way of avoiding slacking and providing robotic support only when the brain is particularly responsive to peripheral input. We tested the feasibility of three-dimensional robotic assistance for reaching movements with a multi-joint exoskeleton during motor imagery (MI)-related desynchronization of sensorimotor oscillations in the β-band. We also registered task-related network changes of cortical functional connectivity by electroencephalography via the imaginary part of the coherence function. Healthy subjects and stroke survivors showed similar patterns—but different aptitudes—of controlling the robotic movement. All participants in this pilot study with nine healthy subjects and two stroke patients achieved their maximum performance during the early stages of the task. Robotic control was significantly higher and less variable when proprioceptive feedback was provided in addition to visual feedback, i.e., when the orthosis was actually attached to the subject’s arm during the task. A distributed cortical network of task-related coherent activity in the θ-band showed significant differences between healthy subjects and stroke patients as well as between early and late periods of the task. Brain-robot interfaces (BRIs) may successfully link three-dimensional robotic training to the participants’ efforts and allow for task-oriented practice of activities of daily living with a physiologically controlled multi-joint exoskeleton. Changes of cortical physiology during the task might also help to make subject-specific adjustments of task difficulty and guide adjunct interventions to facilitate motor learning for functional restoration, a proposal that warrants further investigation in a larger cohort of stroke patients.

Changes in visual and sensory-motor resting-state functional connectivity support motor learning by observing.

Motor learning occurs not only through direct first-hand experience but also through observation (Mattar AA, Gribble PL. Neuron 46: 153-160, 2005). When observing the actions of others, we activate many of the same brain regions involved in performing those actions ourselves (Malfait N, Valyear KF, Culham JC, Anton JL, Brown LE, Gribble PL. J Cogn Neurosci 22: 1493-1503, 2010). Links between neural systems for vision and action have been reported in neurophysiological (Strafella AP, Paus T. Neuroreport 11: 2289-2292, 2000; Watkins KE, Strafella AP, Paus T. Neuropsychologia 41: 989-994, 2003), brain imaging (Buccino G, Binkofski F, Fink GR, Fadiga L, Fogassi L, Gallese V, Seitz RJ, Zilles K, Rizzolatti G, Freund HJ. Eur J Neurosci 13: 400-404, 2001; Iacoboni M, Woods RP, Brass M, Bekkering H, Mazziotta JC, Rizzolatti G. Science 286: 2526-2528, 1999), and eye tracking (Flanagan JR, Johansson RS. Nature 424: 769-771, 2003) studies. Here we used a force field learning paradigm coupled with resting-state fMRI to investigate the brain areas involved in motor learning by observing. We examined changes in resting-state functional connectivity (FC) after an observational learning task and found a network consisting of V5/MT, cerebellum, and primary motor and somatosensory cortices in which changes in FC were correlated with the amount of motor learning achieved through observation, as assessed behaviorally after resting-state fMRI scans. The observed FC changes in this network are not due to visual attention to motion or observation of movement errors but rather are specifically linked to motor learning. These results support the idea that brain networks linking action observation and motor control also facilitate motor learning.

Effects of anodal transcranial direct current stimulation on visually guided learning of grip force control.

Anodal transcranial Direct Current Stimulation (tDCS) has been shown to be an effective non-invasive brain stimulation method for improving cognitive and motor functioning in patients with neurological deficits. tDCS over motor cortex (M1), for instance, facilitates motor learning in stroke patients. However, the literature on anodal tDCS effects on motor learning in healthy participants is inconclusive, and the effects of tDCS on visuo-motor integration are not well understood. In the present study we examined whether tDCS over the contralateral motor cortex enhances learning of grip-force output in a visually guided feedback task in young and neurologically healthy volunteers. Twenty minutes of 1 mA anodal tDCS were applied over the primary motor cortex (M1) contralateral to the dominant (right) hand, during the first half of a 40 min power-grip task. This task required the control of a visual signal by modulating the strength of the power-grip for six seconds per trial. Each participant completed a two-session sham-controlled crossover protocol. The stimulation conditions were counterbalanced across participants and the sessions were one week apart. Performance measures comprised time-on-target and target-deviation, and were calculated for the periods of stimulation (or sham) and during the afterphase respectively. Statistical analyses revealed significant performance improvements over the stimulation and the afterphase, but this learning effect was not modulated by tDCS condition. This suggests that the form of visuomotor learning taking place in the present task was not sensitive to neurostimulation. These null effects, together with similar reports for other types of motor tasks, lead to the proposition that tDCS facilitation of motor learning might be restricted to cases or situations where the motor system is challenged, such as motor deficits, advanced age, or very high task demand.

Motor cortical plasticity and corticospinal tract diffusion tensor image in patients with Parkinson’s disease and essential tremor

s / Brain Stimulation 8 (2015) 326e342 342 Background: Non-invasive brain stimulation (NIBS) protocols can interfere with or even facilitate motor learning. However, it is still unclear whether the response to NIBS protocols, such as theta-burst stimulation (TBS), can predict its ability to interfere with or enhance learning of a motor task. We aim to investigate this question using TBS and a ballistic finger movement task. Methods: Eight right handed healthy human volunteers participated in the study. Experiment 1: We investigated the effects of continuous TBS (cTBS) and intermittent TBS (iTBS) on cortical excitability. Thirty motor evoked potentials (MEP) were measured before and after intervention (cTBS or iTBS) for 30 min. Experiment 2: In separate sessions, we tested the effects of cTBS or iTBS on a ballistic finger movement task. Subjects were required to make rapid index finger abduction movements of the right hand paced at a rate of 0.5 Hz. One block consists of 75 movements for 2.5 min and 4 blocks were tested in total. Between blocks 2 and 3, either cTBS or iTBS was applied over left M1. We quantified the learning effect by measuring the increase the mean peak acceleration (ACC) for each set of 30 consecutive movements. Results: In experiment 1, there was a non-significant trend for MEPs to get smaller after cTBS and larger after iTBS. In experiment 2, cTBS or iTBS did not change ACC immediately after application of TBS. However, ACC increased significantly more in the final block of trials after cTBS than it did after iTBS. The normalized ACC in the last block was negatively correlated with excitability changes induced by cTBS in experiment 1 (Spearman’s r 1⁄4 0.881, p 1⁄4 0.002). Conclusions: This preliminary result suggest that cTBS did not affect early consolidation in M1, but facilitated further performance gains in model-free learning. The effect on performance was correlated with the effect of cTBS on MEPs.

Motor priming in neurorehabilitation.

Priming is a type of implicit learning wherein a stimulus prompts a change in behavior. Priming has been long studied in the field of psychology. More recently, rehabilitation researchers have studied motor priming as a possible way to facilitate motor learning. For example, priming of the motor cortex is associated with changes in neuroplasticity that are associated with improvements in motor performance. Of the numerous motor priming paradigms under investigation, only a few are practical for the current clinical environment, and the optimal priming modalities for specific clinical presentations are not known. Accordingly, developing an understanding of the various types of motor priming paradigms and their underlying neural mechanisms is an important step for therapists in neurorehabilitation. Most importantly, an understanding of the methods and their underlying mechanisms is essential for optimizing rehabilitation outcomes. The future of neurorehabilitation is likely to include these priming methods, which are delivered prior to or in conjunction with primary neurorehabilitation therapies. In this Special Interest article, we discuss those priming paradigms that are supported by the greatest amount of evidence, including (i) stimulation-based priming, (ii) motor imagery and action observation, (iii) sensory priming, (iv) movement-based priming, and (v) pharmacological priming.Video Abstract available. (see Supplemental Digital Content 1, http://links.lww.com/JNPT/A86) for more insights from the authors.

Exploring the utility of analogies in motor learning after stroke

Individuals who have experienced a stroke need to (re)learn motor skills. Analogy learning has been shown to facilitate motor learning in sports and may also be an attractive alternative to traditional approaches in therapy. The aim of this study was to assess the feasibility and utility of analogies to improve the walking performance in long-term stroke survivors. Three men aged 76, 87 and 70 years who were 6, 1 and 3 years poststroke, respectively, presented with different walking deficits. An analogy, targeted at improving the walking performance was designed with the help of each participant. During a 3-week intervention period, the analogy was practiced once weekly under supervision and daily at home. To assess feasibility, a structured interview was conducted at the end of the intervention period. To assess utility, walking performance was assessed using the 10-Metre Walking Test. All three participants were supportive of the feasibility and benefits of analogy learning. Two of the participants had a meaningful improvement on the 10-Metre Walking Test (0.1 and 0.3 m/s). The third participant did not improve most likely because of medication issues during the week of the retest. Developing analogies in therapy is a creative and challenging process, as analogies must not only guide the correct movement pattern, but also be meaningful to the individual. However, as participants were supportive of the use of analogies, and positive trends were seen in walking speed it seems worthwhile to pursue the use of analogies in future research.

A task oriented haptic gait rehabilitation robot

This paper presents the concept, design process, and the prototype of a novel haptics-based lower-extremity rehabilitation robot for bed-ridden stroke patients. This system, named Virtual Gait Rehabilitation Robot (ViGRR), is required to provide the average gait motion training as well as other targeted exercises such as leg press, stair stepping and motivational gaming, in order to facilitate motor learning and enable the training of daily activities such as walking and maintaining balance. The system requirements are laid out and linked to the design of a redundant planar 4DOF robot concept prototype. An iterative design optimization loop was setup to obtain the robot kinematic and dynamic parameters as well as the actuators. The robot’s mechanical design, model, safety features, admittance controllers, and the architecture of the haptic controller are presented. Preliminary experiments were planned and performed to evaluate the capability of the system in delivering task-based virtual-reality exercises and trajectory following scenarios.

Additive benefits of autonomy support and enhanced expectancies for motor learning

Two factors that have been shown to facilitate motor learning are autonomy support (AS) and enhanced expectancies (EE) for performance. We examined the individual and combined influences of these factors. In a 2×2 design, participants learning a novel motor skill (throwing with the non-dominant arm) were or were not provided a choice (AS) about the ball color on each of 6 10-trial blocks during practice, and were or were not given bogus positive social-comparative feedback (EE). This resulted in four groups: AS/EE, AS, EE, and C (control). One day after the practice phase, participants completed 10 retention and 10 transfer trials. The distance to the target – a bull’s eye with a 1m radius and 10 concentric circles – was 7.5m during practice and retention, and 8.5m during transfer. Autonomy support and enhanced expectancies had additive advantages for learning, with both main effects being significant for retention and transfer. On both tests, the AS/EE group showed the greatest throwing accuracy. Also, the accuracy scores of the AS and EE groups were higher than those of the C group. Furthermore, self-efficacy measured after practice and before retention and transfer was increased by both AS and EE. Thus, supporting learners’ need for autonomy by given them a small choice – even though it was not directly related to task performance – and enhancing their performance expectancies appeared to independently influence 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.

A virtual avatar to facilitate gait rehabilitation post-stroke

Augmented visual feedback has the potential to compensate for impairments in intrinsic feedback mechanisms after a stroke and highlight salient information to facilitate motor learning. Although there is much literature to support its use with the healthy population, there is limited evidence for its use with stroke patients [1]. Athletes use feedback via motion capture techniques to enhance their understanding of how to optimise movement patterns. A feasibility study was carried out to explore whether a novel visual feedback aid could facilitate improvements in mobility outcomes after a stroke. Patients and their therapists were shown a virtual avatar that could mimic their movements in real-time, with the option to display range of motion targets at joint centres

Recency Effect of Verbal Summary Knowledge of Results on Motor Performance and Learning

It is necessary to clarify how instructors provide the feedback and how feedback perceived subjectively after motor learners repetitively practice a series of movements. This study was designed to examine the impacts of external and internal information on motor performance and learning. Thirty six participants (21.1 ± 2.3 years) were randomly assigned into one of the summary knowledge of results (SKR) in reverse order, error estimation and summary knowledge of results (EE + SKR) in reverse order, and knowledge of results (KR) 100% groups. Self-paced linear position was used as experimental task. All participants were practiced 84 trials during the acquisition phase, and 10-min immediate retention and 24-hrs delayed retention tests without KR administration. The performance during acquisition phase showed: (1) Groups × blocks interaction were found significant on AE. (2) The change score was found no significant difference. (3) The data from immediate and delayed retention tests showed no significant difference among three groups on AE in immediate retention test, while error estimation in EE + SKR in reverse order group was found significantly higher than that of SKR in reverse order and KR100% groups. Conversely, significant difference was found among three groups on AE and EE in delayed retention tests, and EE + SKR in reverse order was significantly higher EE than that of SKR in reverse order and KR100% groups. These findings suggested that (1) verbal SKR with recency effect was affected by external and internal information on motor performance of movement accuracy, but not in improvement, and (2) verbal SKR with recency effect were facilitated by internal information on motor learning of movement accuracy and error detection, and external information facilitated motor learning of movement accuracy.