Online and offline contributions to motor learning change with practice, but are similar across development

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.

A novel virtual robotic platform for controlling six degrees of freedom assistive devices with body-machine interfaces

Body-machine interfaces (BoMIs)-systems that control assistive devices (e.g., a robotic manipulator) with a person's movements-offer a robust and non-invasive alternative to brain-machine interfaces for individuals with neurological injuries. However, commercially-available assistive devices offer more degrees of freedom (DOFs) than can be efficiently controlled with a user's residual motor function. Therefore, BoMIs often rely on nonintuitive mappings between body and device movements. Learning these mappings requires considerable practice time in a lab/clinic, which can be challenging. Virtual environments can potentially address this challenge, but there are limited options for high-DOF assistive devices, and it is unclear if learning with a virtual device is similar to learning with its physical counterpart. We developed a novel virtual robotic platform that replicated a commercially-available 6-DOF robotic manipulator. Participants controlled the physical and virtual robots using four wireless inertial measurement units (IMUs) fixed to the upper torso. Forty-three neurologically unimpaired adults practiced a target-matching task using either the physical (sample size n = 25) or virtual device (sample size n = 18) involving pre-, mid-, and post-tests separated by four training blocks. We found that both groups made similar improvements from pre-test in movement time at mid-test (Δvirtual: 9.9 ± 9.5 s; Δphysical: 11.1 ± 9.9 s) and post-test (Δvirtual: 11.1 ± 9.1 s; Δphysical: 11.8 ± 10.5 s) and in path length at mid-test (Δvirtual: 6.1 ± 6.3 m/m; Δphysical: 3.3 ± 3.5 m/m) and post-test (Δvirtual: 6.6 ± 6.2 m/m; Δphysical: 3.5 ± 4.0 m/m). Our results indicate the feasibility of using virtual environments for learning to control assistive devices. Future work should determine how these findings generalize to clinical populations.

Children are suboptimal in adapting motor exploration to task dimensionality during motor learning

Motor learning in novel tasks requires exploration to find the appropriate coordination patterns to perform the task. Prior work has shown that compared to adults, children show limited exploration when learning a task that required using upper body movements to control a 2D cursor on a screen. Here, by changing the task dimensionality to 1D, we examined two competing hypotheses: whether children show limited exploration as a general strategy, or whether children are suboptimal in adapting their exploration to task dimensionality. Two groups of children (9- and 12-year olds), and one group of adults learned a virtual task that involved learning to control a cursor on the screen using movements of the upper body. Participants practiced the task for a single session with a total of 232 reaching movements. Results showed that 9-year olds show worse task performance relative to adults, as indicated by higher movement times and path lengths. Analysis of the coordination strategies indicated that both groups of children showed lower variance along the first principal component, suggesting that they had greater exploration than adults which was suboptimal for the 1D task. These results suggest that motor learning in children is characterized not by limited exploration per se, but by a limited adaptability in matching motor exploration to task dimensionality.