A memory of errors in sensorimotor learning Herzfeld, David J.; Vaswani, Pavan A.; Marko, Mollie K. ...
Science (American Association for the Advancement of Science),
09/2014, Letnik:
345, Številka:
6202
Journal Article
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The current view of motor learning suggests that when we revisit a task, the brain recalls the motor commands it previously learned. In this view, motor memory is a memory of motor commands, acquired ...through trial-and-error and reinforcement. Here we show that the brain controls how much it is willing to learn from the current error through a principled mechanism that depends on the history of past errors. This suggests that the brain stores a previously unknown form of memory, a memory of errors. A mathematical formulation of this idea provides insights into a host of puzzling experimental data, including savings and meta-learning, demonstrating that when we are better at a motor task, it is partly because the brain recognizes the errors it experienced before.
Considerable literature on the role of attentional focus in motor performance and learning has accumulated for over two decades. We report the results of comprehensive meta-analyses that address the ...impact of an external focus (EF, on intended movement effects) versus internal focus (IF, on movements of body parts) of attention on the performance and learning of motor skills. Values of effect sizes (ES) from 73 studies with 1,824 participants and 40 studies with 1,274 participants were used for examining the effects of EF versus IF on behavioral outcomes of motor performance and learning (separately for retention and transfer phases) respectively. The EF condition was more effective than the IF condition for performance, Hedges' g value = 0.264 (95% CI 0.217, 0.310), retention learning, Hedges' g value = 0.583 (95% CI 0.425, 0.741), and transfer learning, Hedges' g value = 0.584 (95% CI 0.325, 0.842). Multivariable metaregression analyses on behavioral measures further indicated that neither age group, health status, or skill level, nor their two-way interactions, moderated the ES differences between EF and IF in performance, retention, and transfer models (all p > .100). A secondary analysis on 12 studies with 216 participants that examined the effects of EF versus IF on electromyographic outcomes of motor performance also indicated that EF was associated with more efficient neuromuscular processing, Hedges' g value = 0.833 (95% CI 0.453, 1.213). From nine studies with 272 participants, performance measured by behavioral outcomes was found to be more effective when a more distal, rather than proximal, EF was used, Hedges' g value = 0.224 (95% CI 0.019, 0.429). Overall, the meta-analytic results are consistent with prior narrative reviews and indicate that an external focus is superior to an internal focus whether considering tests of motor performance or learning, and regardless of age, health condition, and level of skill expertise.
Public Significance StatementMeta-analyses show that the use of external focus, by directing attention to intended movement effects, provides advantages for performing and learning motor skills. These beneficial effects are present whether the individual is a child or adult, has a clinical condition or not, and is considered to be a novice, experienced, or an expert at the motor skill.
This study aimed to translate movement patterns, technical skills and tactical actions associated with high-intensity efforts into metrics that could potentially be used to construct ...position-specific conditioning drills. A total of 20 individual English Premier League players' high-intensity running profiles were observed multiple times (n = 100) using a computerised tracking system. Data were analysed using a novel high-intensity movement programme across five positions (centre back CB, full-back FB, central midfielder CM, wide midfielder WM and centre forward CF). High-intensity efforts in contact with the ball and the average speed of efforts were greater in WMs than CBs, CMs and CFs (effect sizes ES: 0.9-2.1, P < 0.05). WMs produced more repeated efforts than CBs and CMs (ES: 0.6-1.3, P < 0.05). In possession, WMs executed more tricks post effort than CBs and CMs (ES: 1.2-1.3, P < 0.01). FBs and WMs performed more crosses post effort than other positions (ES: 1.1-2.0, P < 0.01). Out of possession, CFs completed more efforts closing down the opposition (ES: 1.4-5.0, P < 0.01) but less tracking opposition runners than other positions (ES: 1.5-1.8, P < 0.01). CFs performed more arc runs before efforts compared to CBs, FBs and WMs (ES: 0.9-1.4, P < 0.05), however, CBs completed more 0-90° turns compared to FBs, CMs and WMs (ES: 0.9-1.1, P < 0.01). The data demonstrate unique high-intensity trends in and out of possession that could assist practitioners when devising position-specific drills.
Developmental theories depend on characterizing the input to potential learning mechanisms—infants’ everyday experiences. The current study employed a novel ecological momentary assessment (EMA) to ...measure two aspects of the physical context of those experiences: body position and location. Infant body position was selected because it relates to the development of a variety of other skills. Caregivers of 3‐, 6‐, 9‐, and 12‐month‐olds reported infants’ body position—held, supine, reclined, prone, sitting, or upright—in response to text message notifications over a week to capture infants’ experiences across the entire range of their daily activities. Findings revealed a tremendous disparity in the distribution of body position experiences over the first year. Younger infants spend more time held, supine, and reclined, whereas older infants spend more time sitting and upright. Body position experiences differed substantially between same‐age infants who possess a motor skill (e.g., ability to sit or walk) compared with those who did not, suggesting that developing motor skills change infants’ everyday experiences. Finally, the success of the methodology suggests that similar EMAs might be used to study a wide range of infants’ naturalistic experiences.
Action Observation Training (AOT) promotes the acquisition of motor abilities. However, while the cortical modulations associated with the AOT efficacy are well known, few studies investigated the ...AOT peripheral neural correlates and whether their dynamics move towards the observed model during the training. We administered seventy-two participants (randomized into AOT and Control groups) with training for learning to grasp marbles with chopsticks. Execution practice was preceded by an observation session, in which AOT participants observed an expert performing the task, whereas controls observed landscape videos. Behavioral indices were measured, and three hand muscles' electromyographic (EMG) activity was recorded and compared with the expert. Behaviorally, both groups improved during the training, with AOT outperforming controls. The EMG trainee-model similarity also increased during the training, but only for the AOT group. When combining behavioral and EMG similarity findings, no global relationship emerged; however, behavioral improvements were "locally" predicted by the similarity gain in muscles and action phases more related to the specific motor act. These findings reveal that AOT plays a magnetic role in motor learning, attracting the trainee's motor pattern toward the observed model and paving the way for developing online monitoring tools and neurofeedback protocols.
Fundamental movement skill (FMS) proficiency is positively associated with physical activity and fitness levels. The objective of this study was to systematically review evidence for the benefits of ...FMS interventions targeting youth.
A search with no date restrictions was conducted across 7 databases. Studies included any school-, home-, or community-based intervention for typically developing youth with clear intent to improve FMS proficiency and that reported statistical analysis of FMS competence at both preintervention and at least 1 other postintervention time point. Study designs included randomized controlled trials (RCTs) using experimental and quasi-experimental designs and single group pre-post trials. Risk of bias was independently assessed by 2 reviewers.
Twenty-two articles (6 RCTs, 13 quasi-experimental trials, 3 pre-post trials) describing 19 interventions were included. All but 1 intervention were evaluated in primary/elementary schools. All studies reported significant intervention effects for ≥ 1 FMS. Meta-analyses revealed large effect sizes for overall gross motor proficiency (standardized mean difference SMD = 1.42, 95% confidence interval CI 0.68-2.16, Z = 3.77, P < .0002) and locomotor skill competency (SMD = 1.42, 95% CI 0.56-2.27, Z = 3.25, P = .001). A medium effect size for object control skill competency was observed (SMD = 0.63, 95% CI 0.28-0.98, Z = 3.53, P = .0004). Many studies scored poorly for risk of bias items.
School- and community-based programs that include developmentally appropriate FMS learning experiences delivered by physical education specialists or highly trained classroom teachers significantly improve FMS proficiency in youth.
Roberts, BM, Nuckols, G, and Krieger, JW. Sex differences in resistance training: A systematic review and meta-analysis. J Strength Cond Res 34(5): 1448-1460, 2020-The purpose of this study was to ...determine whether there are different responses to resistance training for strength or hypertrophy in young to middle-aged males and females using the same resistance training protocol. The protocol was pre-registered with PROSPERO (CRD42018094276). Meta-analyses were performed using robust variance random effects modeling for multilevel data structures, with adjustments for small samples using package robumeta in R. Statistical significance was set at P < 0.05. The analysis of hypertrophy comprised 12 outcomes from 10 studies with no significant difference between males and females (effect size ES = 0.07 ± 0.06; P = 0.31; I = 0). The analysis of upper-body strength comprised 19 outcomes from 17 studies with a significant effect favoring females (ES = -0.60 ± 0.16; P = 0.002; I = 72.1). The analysis of lower-body strength comprised 23 outcomes from 23 studies with no significant difference between sexes (ES = -0.21 ± 0.16; P = 0.20; I = 74.7). We found that males and females adapted to resistance training with similar effect sizes for hypertrophy and lower-body strength, but females had a larger effect for relative upper-body strength. Given the moderate effect size favoring females in the upper-body strength analysis, it is possible that untrained females display a higher capacity to increase upper-body strength than males. Further research is required to clarify why this difference occurs only in the upper body and whether the differences are due to neural, muscular, motor learning, or are an artifact of the short duration of studies included.
Cognition presumably emerges from neural activity in the network of association connections between cortical regions that is modulated by inputs from sensory and state systems and directs voluntary ...behavior by outputs to the motor system. To reveal global architectural features of the cortical association connectome, network analysis was performed on >16,000 reports of histologically defined axonal connections between cortical regions in rat. The network analysis reveals an organization into four asymmetrically interconnected modules involving the entire cortex in a topographic and topologic core–shell arrangement. There is also a topographically continuous U-shaped band of cortical areas that are highly connected with each other as well as with the rest of the cortex extending through all four modules, with the temporal pole of this band (entorhinal area) having the most cortical association connections of all. These results provide a starting point for compiling a mammalian nervous system connectome that could ultimately reveal novel correlations between genome-wide association studies and connectome-wide association studies, leading to new insights into the cellular architecture supporting cognition.
Significance Connections between cerebral cortex regions are known as association connections, and neural activity in the network formed by these connections is thought to generate cognition. Network analysis of microscopic association connection data produced over the last 40 years in a small, easily studied mammal suggests a new way to describe the organization of the cortical association network. Basically, it consists of four modules with an anatomical shell–core arrangement and asymmetric connections within and between modules, implying at least partly “hardwired,” genetically determined biases of information flow through the cortical association network. The results advance the goal of achieving a global nervous system wiring diagram of connections and provide another step toward understanding the cellular architecture and mechanisms underpinning cognition.
This analysis sought to determine the associations of the Foundation for the National Institutes of Health Sarcopenia Project criteria for weakness and low lean mass with likelihood for mobility ...impairment (gait speed ≤ 0.8 m/s) and mortality. Providing validity for these criteria is essential for research and clinical evaluation.
Among 4,411 men and 1,869 women pooled from 6 cohort studies, 3-year likelihood for incident mobility impairment and mortality over 10 years were determined for individuals with weakness, low lean mass, and for those having both. Weakness was defined as low grip strength (<26kg men and <16kg women) and low grip strength-to-body mass index (BMI; kg/m(2)) ratio (<1.00 men and <0.56 women). Low lean mass (dual-energy x-ray absorptiometry) was categorized as low appendicular lean mass (ALM; <19.75kg men and <15.02kg women) and low ALM-to-BMI ratio (<0.789 men and <0.512 women).
Low grip strength (men: odds ratio OR = 2.31, 95% confidence interval CI = 1.34-3.99; women: OR = 1.99, 95% CI 1.23-3.21), low grip strength-to-BMI ratio (men: OR = 3.28, 95% CI 1.92-5.59; women: OR = 2.54, 95% CI 1.10-5.83) and low ALM-to-BMI ratio (men: OR = 1.58, 95% CI 1.12-2.25; women: OR = 1.81, 95% CI 1.14-2.87), but not low ALM, were associated with increased likelihood for incident mobility impairment. Weakness increased likelihood of mobility impairment regardless of low lean mass. Mortality risk patterns were inconsistent.
These findings support our cut-points for low grip strength and low ALM-to-BMI ratio as candidate criteria for clinically relevant weakness and low lean mass. Further validation in other populations and for alternate relevant outcomes is needed.
Learning new motor tasks from physical interactions is an important goal for both robotics and machine learning. However, when moving beyond basic skills, most monolithic machine learning approaches ...fail to scale. For more complex skills, methods that are tailored for the domain of skill learning are needed. In this paper, we take the task of learning table tennis as an example and present a new framework that allows a robot to learn cooperative table tennis from physical interaction with a human. The robot first learns a set of elementary table tennis hitting movements from a human table tennis teacher by kinesthetic teach-in, which is compiled into a set of motor primitives represented by dynamical systems. The robot subsequently generalizes these movements to a wider range of situations using our mixture of motor primitives approach. The resulting policy enables the robot to select appropriate motor primitives as well as to generalize between them. Finally, the robot plays with a human table tennis partner and learns online to improve its behavior. We show that the resulting setup is capable of playing table tennis using an anthropomorphic robot arm.
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