Black-box testing in motor sequence learning

During learning of novel motor sequences, practice leads to the consolidation of hierarchical structures, namely motor chunks, facilitating the accurate execution of sequences at increasing speeds. Recent studies show that such hierarchical structures are largely represented upstream of the primary motor cortex in the motor network, suggesting their function to be more related to the encoding, storage, and retrieval of sequences rather than their sole execution. We isolated different components of motor skill acquisition related to the consolidation of spatiotemporal features and followed their evolution over training. We found that optimal motor skill acquisition relies on the storage of the spatial features of the sequence in memory, followed by the optimization of its execution and increased execution speeds (i.e., a shift in the speed-accuracy trade-off) early in training, supporting the model proposed by Hikosaka in 1999. Contrasting the dynamics of these components during ageing, we identified less-than-optimal mechanisms in older adults explaining the observed differences in performance. We applied noninvasive brain stimulation in an attempt to support the aging brain to compensate for these deficits. The present study found that anodal direct current stimulation applied over the motor cortex restored the mechanisms involved in the consolidation of spatial features, without directly affecting the speed of execution of the sequence. This led older adults to sharply improve their accuracy, resulting in an earlier yet gradual emergence of motor chunks. The results suggest the early storage of the sequence in memory, largely independent of motor practice, is crucial for an optimal motor acquisition and retrieval of this motor behavior. Nevertheless, the consolidation of optimal temporal patterns, detected as motor chunks at a behavioral level, is not a direct consequence of storing the sequence elements, but rather of motor practice.

Increasing human motor skill acquisition by driving theta-gamma coupling

Skill learning is a fundamental adaptive process, but the mechanisms remain poorly understood. Some learning paradigms, particularly in the memory domain, are closely associated with gamma activity that is amplitude-modulated by the phase of underlying theta activity, but whether such nested activity patterns also underpin skill learning is unknown. Here we addressed this question by using transcranial alternating current stimulation (tACS) over sensorimotor cortex to modulate theta-gamma activity during motor skill acquisition, as an exemplar of a non-hippocampal-dependent task. We demonstrated, and then replicated, a significant improvement in skill acquisition with theta-gamma tACS, which outlasted the stimulation by an hour. Our results suggest that theta-gamma activity may be a common mechanism for learning across the brain and provides a putative novel intervention for optimising functional improvements in response to training or therapy.

Emergence of perceptuomotor relationships during paleolithic stone toolmaking learning: intersections of observation and practice

Stone toolmaking is a human motor skill which provides the earliest archeological evidence motor skill and social learning. Intentionally shaping a stone into a functional tool relies on the interaction of action observation and practice to support motor skill acquisition. The emergence of adaptive and efficient visuomotor processes during motor learning of such a novel motor skill requiring complex semantic understanding, like stone toolmaking, is not understood. Through the examination of eye movements and motor skill, the current study sought to evaluate the changes and relationship in perceptuomotor processes during motor learning and performance over 90 h of training. Participants’ gaze and motor performance were assessed before, during and following training. Gaze patterns reveal a transition from initially high gaze variability during initial observation to lower gaze variability after training. Perceptual changes were strongly associated with motor performance improvements suggesting a coupling of perceptual and motor processes during motor learning.

Early motor development in infants with moderate or severe bronchopulmonary dysplasia

BACKGROUND: Timely development of early motor skills is essential for later skill development in multiple domains. Infants with severe bronchopulmonary dysplasia (BPD) have significant risk for developmental delays. Early motor skill development in this population has not been described. The aim of the present study was to characterize motor skill acquisition at 3 and 6 months corrected age (CA) and assess trajectories of skill development over this time period in infants with severe BPD. METHODS: We performed a single-center, retrospective descriptive study. Motor skills were categorized as present and normal, present but atypical, or absent at 3 and 6 months CA. Logistic regression was used to identify clinical characteristics associated with negative trajectories of skill acquisition. RESULTS: Data were available for 232 infants and 187 infants at 3 and 6 months CA, respectively. Ten motor skills were present and normal in 5–44%(range) of subjects at 3 months. Nineteen motor skills were present and normal in 1–63%(range) of subjects at 6 months. Significant postural asymmetry was noted throughout the study period. Loss of skills and worsening asymmetries over time were common. Exposure to sedating medications was significantly associated with poor development. CONCLUSION: We report delays in motor skill acquisition and postural asymmetries in infants with severe BPD at both 3 and 6 months CA. The association between sedating medications and poor development suggests that efforts to limit these exposures may lead to improved development. Targeted interventions to facilitate early motor development may improve outcomes of this high-risk population.

The Relationship between Sleep Quality, Sleep-Related Biomarkers and Motor Skill Acquisition in People with Multiple Sclerosis: A Pilot Study

Objective Neurorehabilitation that involves learning new motor skills is one of the promising clinical methods for motor recovery in people with multiple sclerosis (PwMS); therefore, factors that influence the acquisition of motor skills in PwMS need to be investigated. Sleep disturbances are common in PwMS; however, no study has investigated the effect of sleep and sleep-related biomarkers on skill acquisition in PwMS. This study aimed to examine the effect of sleep and sleep-related biomarkers on motor acquisition in PwMS. Methods Forty participants with MS and 40 controls were recruited in this study. To assess motor acquisition, each participant was asked to perform a novel game through a virtual reality (VR) system 5 times (blocks). The main outcome measures for each block were the required time to complete the VR game and the recorded errors. The difference in scores between block 5 and block 1 for both outcomes was considered to represent motor skill acquisition. Sleep was assessed by self-report using the Pittsburgh Sleep Quality Index (PSQI) and objectively using sleep monitor technology. Serotonin level was assessed using means of enzyme-linked immunosorbent assay (ELISA) using plasma samples. Results There were significant positive correlations in both groups between motor skill acquisition and PSQI score. In PwMS, significant negative correlation between motor skill acquisition and sleep efficiency and significant positive correlation between motor skill acquisition and sleep latency were also observed. Interestingly, a significant negative correlation was observed between motor skill acquisition and the plasma serotonin level in both groups. Most of these correlations remained significant after controlling for disease severity, fatigue, baseline performance, and cognitive status. Conclusions Sleep quality may influence motor skill acquisition in PwMS. Circulatory serotonin level might explain this relationship. Impact Physical therapists are encouraged to be aware of sleep quality and sleep assessment. Sleep management strategies should be considered when treating PwMS.

New roles for dopamine in motor skill acquisition: Lessons from primates, rodents, and songbirds

Motor learning is a core aspect of human life, and appears to be ubiquitous throughout the animal kingdom. Dopamine, a neuromodulator with a multifaceted role in synaptic plasticity, may be a key signaling molecule for motor skill learning. Though typically studied in the context of reward-based associative learning, dopamine appears to be necessary for some types of motor learning. Mesencephalic dopamine structures are highly conserved among vertebrates, as are some of their primary targets within the basal ganglia, a subcortical circuit important for motor learning and motor control. With a focus on the benefits of cross-species comparisons, this review examines how "model-free" and "model-based" computational frameworks for understanding dopamine's role in associative learning may be applied to motor learning. The hypotheses that dopamine could drive motor learning either by functioning as a reward prediction error, through passive facilitating of normal basal ganglia activity, or through other mechanisms are examined in light of new studies using humans, rodents, and songbirds. Additionally, new paradigms that could enhance our understanding of dopamine's role in motor learning by bridging the gap between the theoretical literature on motor learning in humans and other species are discussed.

Exploring the Relationship Between Sleep Quality, Sleep-Related Biomarkers, and Motor Skill Acquisition Using Virtual Reality in People With Parkinson's Disease: A Pilot Study

Background and Objectives: Despite the fact that sleep disturbances are among the most common and disabling manifestations of Parkinson's disease (PD), no study has investigated the effect of sleep quality and sleep-related biomarkers on motor skill acquisition in people with Parkinson's disease (PwPD).Objective: To examine the relationship between skill acquisition, sleep quality, and sleep-related biomarkers in PwPD using virtual reality (VR) system.Methods: This is a cross sectional study conducted on 31 PwPD and 31 healthy controls. To assess skill acquisition, each participant practiced a VR game 6 times (blocks). The main outcomes from the VR game were the required time to complete the VR game and the recorded errors. Motor skill acquisition was calculated as the difference of scores between block 6 and block 2 for both outcomes. Sleep was assessed subjectively using Pittsburgh Sleep Quality Index (PSQI) and objectively using the Actisleep. To assess sleep related biomarker, plasma serotonin level was examined.Results: PwPD and healthy controls demonstrated a practice-related improvement in performance as shown by the main effect of block for each of the VR outcome measures (p < 0.000, time required to complete VR game; p < 0.000, recorded errors). There was no interaction effect between Block X Group for both outcome measures. There were significant correlations in both groups (p < 0.05) between motor skill acquisition (as indicated by the difference of time required to complete the VR game between block 6 and block 2) and PSQI total score, wake after sleep onset, and sleep efficiency. Additionally, a significant correlation was observed in both groups between motor skill acquisition (as indicated by the difference of time required to complete the VR game between block 6 and block 2) and the plasma serotonin level (p < 0.05). These correlations in PwPD remained significant, even after adjusting for disease motor severity, cognitive status, depression, and daily dose of L-dopa.Discussion and Conclusions: Sleep quality may influence motor skill acquisition in PwPD. Healthcare professionals are encouraged to be aware about sleep quality and sleep assessment tools. Therapies may target improving sleep quality which could result in improving motor skill acquisition.

Dexterity of the Less Affected Hand in Children With Hemiplegic Cerebral Palsy

Background: To determine if the “unaffected” hand in children with hemiplegic cerebral palsy (CP) is truly unaffected. Methods: We performed a retrospective review of manual dexterity as measured by the Functional Dexterity Test (FDT) in 66 children (39 boys, 27 girls, mean age: 11 years 4 months) with hemiplegic CP. Data were stratified by Manual Ability Classification System (MACS) level, birth weight, and gestational age at birth, and compared with previously published normative values. Results: The FDT speed of the less affected hand is significantly lower than typically developing (TD) children ( P < .001). The development of dexterity is significantly lower than TD children (0.009 vs. 0.036 pegs/s/year, P < .001), with a deficit that increases with age. MACS score, birth weight, and age at gestation are not predictors of dexterity. The dexterity of the less affected hand is poorly correlated with that of the more affected hand. Conclusions: Both dexterity and rate of fine motor skill acquisition in the less affected hand of children with hemiplegic CP is significantly less than that of TD children. The less affected hand should be evaluated and included in comprehensive treatment plans for these children.