Retention Of Motor Skill Research Articles

Failure to Engage Neural Plasticity through Practice of a High-difficulty Task is Accompanied by Reduced Motor Skill Retention in Older Adults

While the difficulty of a motor task can act as a stimulus for learning in younger adults, it is unknown how task difficulty interacts with age-related reductions in motor performance and altered brain activation. We examined the effects of task difficulty on motor performance and used electroencephalography (EEG) to probe task-related brain activation after acquisition and 24-h retention of a mirror star-tracing skill in healthy older adults (N = 36, 65–86 years). The results showed that the difficulty of the motor skill affected both the magnitude of motor skill learning and the underlying neural mechanisms. Behavioral data revealed that practicing a motor task at a high difficulty level hindered motor skill consolidation. The EEG data indicated that task difficulty modulated changes in brain activation after practice. Specifically, a decrease in task-related alpha power in frontal and parietal electrodes was only present after practice of the skill at the low and medium, but not the high difficulty level. Taken together, our findings show that a failure to engage neural plasticity through practice of a high-difficulty task is accompanied by reduced motor skill retention in older adults. The data help us better understand how older adults learn new motor skills and might have implications for prescribing motor skill practice according to its difficulty in rehabilitation settings.

Transcranial Alternating Current Stimulation of the Primary Motor Cortex after Skill Acquisition Improves Motor Memory Retention in Humans: A Double-Blinded Sham-Controlled Study.

Consolidation leading to retention of motor memory following motor practice involves activity-dependent plastic processes in the corticospinal system. To investigate whether beta-band transcranial alternating current stimulation (tACS) applied immediately following skill acquisition can enhance ongoing consolidation processes and thereby motor skill retention 20 adults participated in a randomized, double-blinded, sham-controlled study. Participants received tACS at peak beta-band corticomuscular coherence (CMC) frequency or sham tACS for 10 min following practice of a visuomotor ankle dorsiflexion task. Performance was measured as the average percentage time on target. Electroencephalograhy (EMG) was measured at Cz and EMG from the right tibialis anterior muscle. CMC and intramuscular coherence (IMC) were estimated during 2-min tonic dorsiflexion. Motor skill retention was tested 1 and 7 days after motor practice. From the end of motor practice to the retention tests, motor performance improved more in the tACS group compared with the sham tACS group after 1 (P = 0.05) and 7 days (P < 0.001). At both retention tests, beta-band IMC increased in the tACS group compared with post-tACS. Beta-band CMC increased in the tACS group at retention day 1 compared with post-tACS. Changes in CMC but not IMC were correlated with performance 1 and 7 days following practice. This study shows that tACS applied at beta-band CMC frequency improves consolidation following visuomotor practice and increases beta-band CMC and IMC. We propose that oscillatory beta activity in the corticospinal system may facilitate consolidation of the motor skill.

Consolidation and retention of motor skill after motor imagery training

Complex motor tasks are learned through training which results in lasting improvement in sensorimotor performance and accuracy. Learning a motor skill is commonly attained via physical execution. However, research has shown that cognitive training, such as motor imagery (MI), effectively facilitates skill learning. Neurophysiological findings suggest that learning-induced plasticity in the human motor cortex, subserving consolidation and retention of motor skills, is stronger after movement execution (ME) than after MI training. Here, we designed an experimental task able to test for the fast and slow learning phases and for retention of motor skills for both MI and ME. We hypothesize that differences between MI and ME training would emerge in terms of reduced consolidation and retention of motor skills. Twenty-four young healthy subjects were divided into two groups, performing MI or ME training. Participants wore sensor-engineered gloves and their sensorimotor performance was assessed over a period of 15 days with 4-days training. We analysed the touch duration (TD), the inter-tapping interval (ITI), movement rate and accuracy. Results showed that (i) during the first phase of acquisition of motor skills, sensorimotor performance improved similarly in MI and ME groups; (ii) during the second learning phase movement rate increased more in ME than MI group and this difference was mainly driven by differences in the duration of TD; (iii) consolidation deficits with MI training reflected in impaired retention of the acquired skills, as TD and ITI were larger and movement rate was lower in the MI group with respect to the ME, till to 10 days after the last training session. Explicit component of motor learning, accuracy, was maintained in retention phase in both groups. Following our hypothesis, our findings show that MI training is as effective as ME within the first learning phase, but consolidation and retention of motor skills are less effective following MI training. This study highlights MI limitations and suggests option to enhance MI, as by providing an external sensory feedback.

Transcranial Direct Current Stimulation of Supplementary Motor Region Impacts the Effectiveness of Interleaved and Repetitive Practice Schedules for Retention of Motor Skills

Interleaved rather than repetitive practice (RP) is associated with superior retention of motor skills. It has been argued that this results from improved post-practice consolidation reflected in greater offline gains following interleaved practice (IP). The magnitude of this offline benefit has been associated with greater recruitment of supplementary motor area (SMA) during encoding. The present study administered anodal or cathodal transcranial direct current stimulation (tDCS) during interleaved or RP respectively in an attempt to modify the activity at SMA and the concomitant retention outcomes commonly associated with these training formats. Sixty-nine participants were assigned to one of four experimental conditions that included: IP-sham, RP-sham, IP-cathodal tDCS, and RP-anodal tDCS. Real or sham stimulation at SMA was administered during practice of three unique 6-key discrete sequence production tasks which lasted approximately 20-min. Tests were administered prior to practice and immediately after practice as well at 6-h, 24-h, and 72-h after practice ended. As anticipated, IP resulted in poorer acquisition but superior offline gain. Enhanced offline gain following interleaved training resulted from rapid stabilization of performance within the first 6-h following encoding and overnight improvement that continued over multiple sleep episodes. Administration of anodal stimulation at SMA during RP improved performance during training compared to sham but this benefit was short lived as forgetting during the first 6-h after practice was consistent with that observed for the sham counterpart. However, supplementing RP with anodal stimulation at SMA did foster overnight offline performance gains not displayed by individuals that experienced RP in the absence of stimulation.

Sequential Reaching Task for the Study of Motor Skills in Monkeys.

The ability to perform a sequence of movements is a key component of motor skills, such as typing or playing a musical instrument. How the brain binds elementary movements together into meaningful actions has been a topic of much interest. Here, we describe two sequential reaching tasks that we use to investigate the neural substrate of skilled sequential movements in monkeys after long-term practice. The movement elements performed in these tasks are essentially identical, but are generated in two different contexts. In one task, monkeys perform reaching movements that are instructed by visual cues. In the other, the monkeys perform reaching movements that are generated from memory after extended practice. With this behavioral paradigm, we can dissociate the neural processes related to the acquisition and retention of motor skills from those related to movement execution.

A Delayed Advantage: Multi-Session Training at Evening Hours Leads to Better Long-Term Retention of Motor Skill in the Elderly.

The acquisition and retention of motor skills is necessary for everyday functioning in the elderly and may be critical in the context of motor rehabilitation. Recent studies indicate that motor training closely followed by sleep may result in better engagement of procedural (“how to”) memory consolidation processes in the elderly. Nevertheless, elderly individuals are mostly morning oriented and a common practice is to time rehabilitation programs to morning hours. Here, we tested whether the time-of-day wherein training is afforded (morning, 8–10:30 a.m., or evening, 6–9 p.m.) affects the long-term outcome of a multi-session motor practice program (10 sessions across 3–4 weeks) in healthy elderly participants. Twenty-nine (15 women) older adults (60–75 years) practiced an explicitly instructed five-element key-press sequence by repeatedly generating the sequence “as fast and accurately as possible.” The groups did not differ in terms of sleep habits and quality (1-week long actigraphy); all were morning-oriented individuals. All participants gained robustly from the intervention, shortening sequence tapping duration and retaining the gains (> 90%) at 1-month post-intervention, irrespective of the time-of-day of training. However, retesting at 7-months post-intervention showed that the attrition of the training induced gains was more pronounced in the morning trained group compared to the evening group (76 and 56.5% loss in sequence tapping time; 7/14 and 3/14 participants showed a > 5% decline in accuracy relative to end of training, respectively). Altogether, the results show that morning-oriented older adults effectively acquired skill in the performance of a sequence of finger movements, in both morning and evening practice sessions. However, evening training leads to a significant advantage, over morning training, in the long-term retention of the skill. Evening training should be considered an appropriate time window for motor skill learning in older adults, even in individuals with morning chronotype. The results are in line with the notion that motor training preceding a sleep interval may be better consolidated into long-term memory in the elderly, and thus result in lower forgetting rates.

Aging Does Not Affect Beta Modulation during Reaching Movements.

During movement, modulation of beta power occurs over the sensorimotor areas, with a decrease just before its start (event-related desynchronization, ERD) and a rebound after its end (event-related synchronization, ERS). We have recently found that the depth of ERD-to-ERS modulation increases during practice in a reaching task and the following day decreases to baseline levels. Importantly, the magnitude of the beta modulation increase during practice is highly correlated with the retention of motor skill tested the following day. Together with other evidence, this suggests that the increase of practice-related modulation depth may be the expression of sensorimotor cortex's plasticity. Here, we determine whether the practice-related increase of beta modulation depth is equally present in a group of younger and a group of older subjects during the performance of a 30-minute block of reaching movements. We focused our analyses on two regions of interest (ROIs): the left sensorimotor and the frontal region. Performance indices were significantly different in the two groups, with the movements of older subjects being slower and less accurate. Importantly, both groups presented a similar increase of the practice-related beta modulation depth in both ROIs in the course of the task. Peak latency analysis revealed a progressive delay of the ERS peak that correlated with the total movement time. Altogether, these findings support the notion that the depth of beta modulation in a reaching movement task does not depend on age and confirm previous findings that only ERS peak latency but not ERS magnitude is related to performance indices.

P104. The impact of timing of cerebellar anodal transcranial direct current stimulation on motor performance in a sequential finger tapping task

Background Transcranial direct current stimulation (tDCS) of the cerebellum could constitute an innovative approach in understanding the role of cerebellar function in healthy and pathological conditions. Recently, attention has grown toward cerebellar neuromodulation in motor learning using tDCS. An important point of discussion regarding this modulation is the optimal timing of tDCS. As this parameter could significantly influence the outcome, we aimed to compare the effect of anodal cerebellar tDCS applied at different times on the motor performance and retention using a sequential finger tapping task (FTT). Methods Fifty-six healthy young, right-handed subjects performed two days of FTT on a custom keyboard. The task was presented with OpenSesame software and lasted 40 s followed by 20 s rest forming one trial. Each participant performed 20 trials on the first day (20 min) and 10 trials on the following one (10 min). tDCS (2 mA, sponge electrodes of 25 cm2, duration 20 min) was applied to the ipsilateral cerebellar hemisphere on day 1 at the following times: (1) before ‘tDCS-before’, (2) sham during ‘tDCS-sham’, (3) active during ‘tDCS-active’ or (4) after the training ‘tDCS-after’. Motor skill performance and retention were assessed. Results All participants showed significant effects of learning ( p 0.0001 ). The mean performance on day 1 was significantly different ( p 0.0001 ): The tDCS-after group performed better than all the other groups, whereas the tDCS-active group performed worse than the tDCS-before group. Similarly, there was a significant difference in the mean performance on day 2 ( p 0.0001 ): tDCS-after was associated with a better performance on day 2, compared to tDCS-sham and tDCS-active. The tDCS-before group also performed better than the tDCS-sham or the tDCS-active groups. Motor skill retention was not different between the groups (p = 0.15). Discussion Cerebellar tDCS applied during the FTT (‘on-line’) interfered with task execution, resulting in an impaired performance on days 1 and 2 compared to the other groups. This inhibitory effect of anodal tDCS may caution against a simple transfer of tDCS’ effects on the motor cortex to regions with a different architecture like the cerebellum. It calls for a careful attention to the timing of stimulation when designing experiments with tDCS. Cerebellar tDCS did not facilitate the retention of the motor skill in the FTT – however, it cannot be excluded that young healthy subjects already performed at a near optimal level with little room for further improvement. Future work will evaluate the effect of cerebellar tDCS in a population where motor learning and cerebellar volume are known to decline.

Acute cardiovascular exercise promotes functional changes in cortico-motor networks during the early stages of motor memory consolidation

A single bout of cardiovascular exercise performed immediately after practicing a visuo-motor tracking task has been shown to improve the long-term retention of this motor skill through an optimization of the memory consolidation process. The mechanisms underlying the time-dependent effects of acute cardiovascular exercise on motor memory consolidation, however, remain poorly understood. In this study, we sought to determine the impact of a single bout of cardiovascular exercise performed immediately after motor skill practice on those mechanisms using electroencephalography (EEG) and electromyography (EMG). Specifically, we assessed exercise-induced changes in the activity and connectivity of cortico-motor networks during early consolidation and the impact of these changes on skill retention. Participants practiced a visuo-motor tracking task followed by either a short bout of intense exercise or a rest period. EEG along with EMG data of hand muscles were collected during the production of low-force isometric contractions. Event-related desynchronization, functional connectivity and corticomuscular coherence were measured at baseline, 30, 60 and 90 min after the bout of exercise or the rest period. Improvements in motor memory were inferred via retention tests of the motor skill performed 8 and 24 h after motor practice. We found that participants who performed the single bout of exercise showed better motor skill retention 24 h after motor practice. This improvement in skill retention in the exercise group was associated with significant decreases in beta-band event-related desynchronization in EEG electrodes located over the left sensorimotor areas. We also found that after exercise, alpha-, and even more significantly, beta-band functional connectivity, increased between EEG electrodes located over left and right sensorimotor areas. The exercise group also showed greater beta-band corticomuscular coherence but only in a small number of electrodes. Neither functional connectivity nor corticomuscular coherence measures correlated with skill retention scores. This is the first study exploring brain mechanisms underlying the summative effects of motor learning and cardiovascular exercise on motor memory consolidation. We have identified potential neural substrates through which a single bout of acute exercise, when performed in close temporal proximity to motor practice, strengthens motor memories. Our findings provide new mechanistic insights into a better understanding of the complex temporal relationship existing between cardiovascular exercise and motor memory consolidation.

Visuospatial function predicts one-week motor skill retention in cognitively intact older adults.

Motor learning declines with aging, such that older adults retain less motor skill after practice compared to younger adults. However, it remains unclear if these motor learning declines are related to normal cognitive changes associated with aging. The purpose of this study was to examine which cognitive domains would best predict the amount of retention on a motor task one week after training in cognitively intact older adults. Twenty-one adults ages 65-84 years old were assessed with Repeatable Battery for the Assessment of Neuropsychological Status, which assesses five cognitive domains (immediate and delayed memory, visuospatial/constructional, language, and attention). Participants also completed one training session of a functional upper extremity task, and were re-tested one week later. Stepwise regression indicated that the visuospatial domain was the only significant predictor of how much skill participants retained over one week, with a visual perception subtest explaining the most variance. Results from this study support previous work reporting that older adults' capacity for motor learning can be probed with visuospatial tests. These tests may capture the structural or functional health of neural networks critical for skill learning within the aging brain, and provide valuable clinical insight about an individual's unique rehabilitation potential.

P 68 Novel control concepts and motor re-learning strategy in neurorehabilitation – practically-oriented approach

Background and motivation Persons suffering from functional impairment, due to cerebral palsy, stroke, or Parkinson’s, often have not reached their full potential for recovery which often is a reason for injures and loss of life due to fall. Motor skill learning and retention of motor skills can be enhanced if a patient assumes control over practice conditions, e.g. timing of exercise instructions and feedback. In our study, we follow a novel conceptual framework ( Despotova and Kiriazov, 2015 ) for optimal control learning of goal-directed motion tasks, like reaching, standing up and walking. Currently we are designing an adequate control strategy for posture stabilization tasks, too. ( Despotova et al., xxxx ). Generally speaking our research on neurorehabilitation is based on underlying principles and novel concepts of neurophysiology, multi-segmental dynamics, optimal control theory, and control learning (CL). Methods Our approach is based on the real dynamics and its control concepts are biologically plausible. Moreover, the proposed CL approach has the necessary mathematical guarantees for its feasibility and convergence. For dynamic goal-directed movements, we can apply an efficient CL scheme which has the following main stages: • Choose a set of appropriate test control functions • Define the most relevant pairs of control parameters and controlled outputs • Perform control parameter optimization in training exercises Of primary importance is to define a set of variables that best characterize the dynamic performance in the required motion task. We make corrections in the control parameters until reach the target, applying efficient, natural learning algorithms. Results Our control concepts have been verified in numerous computer simulations. The proposed approach is successfully applied using human body models with 2, 3, 4 and 6 degrees of freedom representing reaching ( Fig. 1 ), standing up, and walking motion in sagittal plane, Fig. 2 . In Fig. 1 , the convergence to the target in a reaching motion task is achieved after a very small number of trials. The efficiency of our CL algorithm is confirmed also in a real body experiment – healthy subject performing fast reaching (ballistic-like) movements. Special attention in our current research is devoted to the challenging problem of CL in the real, three-dimensional human locomotion. We can perform proper decomposition of this complex motion task into several goal-directed movements and apply the proposed CL scheme for each of them. Discussion We believe that the proposed approach can be used to rebuild the so-called internal models (cortical reorganization) by proper training procedures. The work outlined here can provide a fundamental understanding of motor learning and may lead to the development of optimal strategies for efficient neuro-muscular rehabilitation. In addition we have found that our approach is very promising and could be efficiently applied to the more complex, human/robot systems. Various assistive devices may be used for restoration of human movement functionality, such as passive and active orthoses, robotic exoskeletons, EMG, FES, brain-computer interfaces (BCI).

Provision of somatosensory inputs during motor imagery enhances learning-induced plasticity in human motor cortex

Motor learning via physical practice leads to long-term potentiation (LTP)-like plasticity in motor cortex (M1) and temporary occlusion of additional LTP-like plasticity. Motor learning can be achieved through simulation of movement, namely motor imagery (MI). When combined with electrical stimulation, MI influenced M1 excitability to a larger extent than MI itself. We explored whether a training based on the combination of MI and peripheral nerve stimulation (ESMI) modulates M1 LTP-like plasticity inducing retention of a new acquired skill. Twelve subjects mentally performed thumb-index movements, with synchronous electrical nerve stimulation, following an acoustic cue, in order to increase movement speed. Two control groups physically performed or imagined the same number of finger movements following the acoustic cue. After each training session, M1 LTP-like plasticity was assessed by using PAS25 (paired associative stimulation) technique. Performance was tested before and after training and 24 hours after training. Results showed that physical practice and ESMI training similarly increased movement speed, prevented the subsequent PAS25-induced LTP-like plasticity, and induced retention of motor skill the following day. Training with MI had significant, but minor effects. These findings suggest that a training combining MI with somatosensory input influences motor performance through M1 plasticity similarly to motor execution.

Lack of spacing effects during piano learning.

Spacing effects during retention of verbal information are easily obtained, and the effect size is large. Relatively little evidence exists on whether motor skill retention benefits from distributed practice, with even less evidence on complex motor skills. We taught a 17-note musical sequence on a piano to individuals without prior formal training. There were five lags between learning episodes: 0-, 1-, 5-, 10-, and 15-min. After a 5-min retention interval, participants’ performance was measured using three criteria: accuracy of note playing, consistency in pressure applied to the keys, and consistency in timing. No spacing effect was found, suggesting that the effect may not always be demonstrable for complex motor skills or non-verbal abilities (timing and motor skills). Additionally, we taught short phrases from five songs, using the same set of lags and retention interval, and did not find any spacing effect for accuracy of song reproduction. Our findings indicate that although the spacing effect is one of the most robust phenomena in the memory literature (as demonstrated by verbal learning studies), the effect may vary when considered in the novel realm of complex motor skills such as piano performance.

A Single Bout of High-Intensity Interval Training Improves Motor Skill Retention in Individuals With Stroke

Background. One bout of high-intensity cardiovascular exercise performed immediately after practicing a motor skill promotes changes in the neuroplasticity of the motor cortex and facilitates motor learning in nondisabled individuals. Objective. To determine if a bout of exercise performed at high intensity is sufficient to induce neuroplastic changes and improve motor skill retention in patients with chronic stroke. Methods. Twenty-two patients with different levels of motor impairment were recruited. On the first session, the effects of a maximal graded exercise test on corticospinal and intracortical excitability were assessed from the affected and unaffected primary motor cortex representational area of a hand muscle with transcranial magnetic stimulation. On the second session, participants were randomly assigned to an exercise or a nonexercise control group. Immediately after practicing a motor task, the exercise group performed 15 minutes of high-intensity interval training while the control group rested. Twenty-four hours after motor practice all participants completed a test of the motor task to assess skill retention. Results. The graded exercise test reduced interhemispheric imbalances in GABAA-mediated short-interval intracortical inhibition but changes in other markers of excitability were not statistically significant. The group that performed high-intensity interval training showed a better retention of the motor skill. Conclusions. The performance of a maximal graded exercise test triggers only modest neuroplastic changes in patients with chronic stroke. However, a single bout of high-intensity interval training performed immediately after motor practice improves skill retention, which could potentially accelerate motor recovery in these individuals.

Randomized Trial on the Effects of Attentional Focus on Motor Training of the Upper Extremity Using Robotics With Individuals After Chronic Stroke

ObjectiveTo compare the long-term effects of external focus (EF) and internal focus (IF) of attention after 4 weeks of arm training. DesignRandomized, repeated-measures, mixed analysis of variance. SettingOutpatient clinic. ParticipantsIndividuals with stroke and moderate-to-severe arm impairment living in the community (N=33; withdrawals: n=3). InterventionsFour-week arm training protocol on a robotic device (12 sessions). Main Outcome MeasuresJoint independence, Fugl-Meyer Assessment, and Wolf Motor Function Test measured at baseline, discharge, and 4-week follow-up. ResultsThere were no between-group effects for attentional focus. Participants in both groups improved significantly on all outcome measures from baseline to discharge and maintained those changes at 4-week follow-up regardless of group assignment (joint independence EF condition: F1.6,45.4=17.74; P<.0005; partial η2=.39; joint independence IF condition: F2,56=18.66; P<.0005; partial η2=.40; Fugl-Meyer Assessment: F2,56=27.83; P<.0005; partial η2=.50; Wolf Motor Function Test: F2,56=14.05; P<.0005; partial η2=.35). ConclusionsThere were no differences in retention of motor skills between EF and IF participants 4 weeks after arm training, suggesting that individuals with moderate-to-severe arm impairment may not experience the advantages of an EF found in healthy individuals. Attentional focus is most likely not an active ingredient for retention of trained motor skills for individuals with moderate-to-severe arm impairment, whereas dosage and intensity of practice appear to be pivotal. Future studies should investigate the long-term effects of attentional focus for individuals with mild arm impairment.

Beta Oscillatory Changes and Retention of Motor Skills during Practice in Healthy Subjects and in Patients with Parkinson's Disease.

Recently we found that modulation depth of beta power during movement increases with practice over sensory-motor areas in normal subjects but not in patients with Parkinson's disease (PD). As such changes might reflect use-dependent modifications, we concluded that reduction of beta enhancement in PD represents saturation of cortical plasticity. A few questions remained open: What is the relation between these EEG changes and retention of motor skills? Would a second task exposure restore beta modulation enhancement in PD? Do practice-induced increases of beta modulation occur within each block? We thus recorded EEG in patients with PD and age-matched controls in two consecutive days during a 40-min reaching task divided in fifteen blocks of 56 movements each. The results confirmed that, with practice, beta modulation depth over the contralateral sensory-motor area significantly increased across blocks in controls but not in PD, while performance improved in both groups without significant correlations between behavioral and EEG data. The same changes were seen the following day in both groups. Also, beta modulation increased within each block with similar values in both groups and such increases were partially transferred to the successive block in controls, but not in PD. Retention of performance improvement was present in the controls but not in the patients and correlated with the increase in day 1 modulation depth. Therefore, the lack of practice-related increase beta modulation in PD is likely due to deficient potentiation mechanisms that permit between-block saving of beta power enhancement and trigger mechanisms of memory formation.

Effects of practice and delays on learning and retention of skilled tool use in Parkinson's disease

Previous research has shown that individuals with Parkinson's disease (PD) show preserved learning of tool-related motor skills, while retention was impaired after a three-week delay, possibly as a result of striatal dysfunction. The goal of the current study was to identify if shorter delays and more extensive practice might reduce retention deficits related to complex tool use in PD. PD participants and healthy age and education-matched controls were trained to use novel tools across four sessions, spaced one-day, one-week, and three-weeks apart. Recall of tool attributes (e.g., function) and skilled motor performance using tools was investigated by examining patterns of learning and forgetting over time. Results showed that tool attribute recall was unimpaired in PD participants relative to controls. For motor skill performance, PD participants were unimpaired in motor skill learning within sessions, but they did not retain these skills across one-week and three-week delays between sessions. This dissociation suggests that the striatum plays a critical role in retention of motor skills needed in skilled tool use performance. Finally, in spite of forgetting, individuals with PD still demonstrated improvement across sessions with additional training, suggesting that people with PD may benefit from extensive practice when learning motor skills.

The effects of autonomous difficulty selection on engagement, motivation, and learning in a motion-controlled video game task

This experiment investigated the relationship between motivation, engagement, and learning in a video game task. Previous studies have shown increased autonomy during practice leads to superior retention of motor skills, but it is not clear why this benefit occurs. Some studies suggest this benefit arises from increased motivation during practice; others suggest the benefit arises from better information processing. Sixty novice participants were randomly assigned to a self-controlled group, who chose the progression of difficulty during practice, or to a yoked group, who experienced the same difficulty progression but did not have choice. At the end of practice, participants completed surveys measuring intrinsic motivation and engagement. One week later, participants returned for a series of retention tests at three different difficulty levels. RM-ANCOVA (controlling for pre-test) showed that the self-controlled group had improved retention compared to the yoked group, on average, β=46.78, 95% CI=[2.68, 90.87], p=0.04, but this difference was only statistically significant on the moderate difficulty post-test (p=0.004). The self-controlled group also showed greater intrinsic motivation during practice, t(58)=2.61, p=0.01. However, there was no evidence that individual differences in engagement (p=0.20) or motivation (p=0.87) were associated with learning, which was the relationship this experiment was powered to detect. These data are inconsistent with strictly motivational accounts of how autonomy benefits learning, instead suggesting the benefits of autonomy may be mediated through other mechanisms. For instance, within the information processing framework, the learning benefits may emerge from learners appropriately adjusting difficulty to maintain an appropriate level of challenge (i.e., maintaining the relationship between task demands and cognitive resources).

Short-term immobilization influences use-dependent cortical plasticity and fine motor performance

Short-term immobilization that reduces muscle use for 8–10h is known to influence cortical excitability and motor performance. However, the mechanisms through which this is achieved, and whether these changes can be used to modify cortical plasticity and motor skill learning, are not known. The purpose of this study was to investigate the influence of short-term immobilization on use-dependent cortical plasticity, motor learning and retention. Twenty-one adults were divided into control and immobilized groups, both of which underwent two experimental sessions on consecutive days. Within each session, transcranial magnetic stimulation (TMS) was used to assess motor-evoked potential (MEP) amplitudes, short- (SICI) and long-interval intracortical inhibition (LICI), and intracortical facilitation (ICF) before and after a grooved pegboard task. Prior to the second training session, the immobilized group underwent 8h of left hand immobilization targeting the index finger, while control subjects were allowed normal limb use. Immobilization produced a reduction in MEP amplitudes, but no change in SICI, LICI or ICF. While motor performance improved for both groups in each session, the level of performance was greater 24-h later in control, but not immobilized subjects. Furthermore, training-related MEP facilitation was greater after, compared with before, immobilization. These results indicate that immobilization can modulate use-dependent plasticity and the retention of motor skills. They also suggest that changes in intracortical excitability are unlikely to contribute to the immobilization-induced modification of cortical excitability.

Motor Skill Retention Is Modulated by Strategy Choice During Self-Controlled Knowledge of Results Schedules

Investigations into the strategies that are used by participants when they control their knowledge of results (KR) schedule during practice have predominantly relied on multiple-choice questionnaires. More recently, open-ended questions have been used to allow participants to produce their own descriptions rather than selecting a strategy from a predetermined list. This approach has in fact generated new information about the cognitive strategies used by learners to request KR during practice (e.g., Laughlin et al., 2015). Consequently, we examined strategy use in self-controlled KR learning situations using open-ended questions at two different time points during practice. An inductive thematic content analysis revealed five themes that represented participants’ unique strategies for requesting KR. This analysis identified two dominant KR strategies: “establish a baseline understanding” in the first half of practice and “confirm a perceived good trial” in the second half of practice. Both strategies were associated with superior retention compared with a yoked group, a group that was unable to engage in KR request strategies because KR was imposed rather than chosen. Our results indicate that the learning advantages of self-controlled KR schedules over yoked schedules may not only depend on what strategy is used, but also when it is used.