Motor learning and COMT Val158met polymorphism: Analyses of oculomotor behavior and corticocortical communication.

Differences in motor learning can be partially explained by differences in genotype. The catechol-O-methyltransferase (COMT) Val158Met polymorphism regulates the dopamine (DA) availability in the prefrontal cortex modulating motor learning and performance. Given the differences in tonic and phasic DA transmission, this study aimed to investigate whether the greater cognitive flexibility associated with the Val allele would favor the learning of movement parametrization, while the greater cognitive stability associated with the Met allele favors the acquisition of the movement pattern. Furthermore, we investigated if the genotypic characteristics impact visual scanning of information related to parametrization and to the movement pattern, and the level of cortical connectivity associated with motor planning and control. Performance and learning of a sequential motor task were compared among three genotypes (Val/Val, Val/Met, and Met/Met), as well as their oculomotor behavior and level of cortical coherence. The findings show that the cognitive flexibility promoted by the Val allele is associated with a better parametrization. The search for information through visual scanning was specific to each genotype. Also, a greater cortical connectivity associated with the Val allele was found. The combined study of behavioral, electrophysiological and molecular levels of analysis showed that the cognitive stability and flexibility associated with the COMT alleles, influence specific aspects of motor learning.

Different Faces of Variability in the Adaptive Process of Motor Skill Learning.

This study investigated the variability by considering an action programme as hierarchically organized, which reconciles invariant and variant features of motor skills at the macro- and microstructural level of analysis. It was assumed that invariant aspects of skilled actions express the macrostructure and therefore measures of sequencing, relative size, relative timing, relative force and relative pause time. The microstructure was related to the variant aspects so that total size, total movement time, total force, and total pause time were selected as its measures. These propositions were tested in an experimental design comprised by three learning phases: a stabilisation phase that entailed a given number of trials to achieve the functional stabilization on a graphic task, followed by transfer and retention phases. In the transfer phase, the graphic task was modified to yield different demands upon skill reorganization. Two such modifications demanded parametric changes (i.e. microstructure changes), in which graphic size and drawing speed were altered. Another modification demanded structural alterations (i.e. macrostructure change), in which drawing was changed. Overall, results supported the main predictions by showing that parametric changes in the task affected the microstructure, but did not affect the macrostructure consistently. Furthermore, a structural change affected both macro- and microstructure.

Effects of knowledge of results frequency on the learning of generalized motor programs and parameters under conditions of constant practice.

The present study investigated the effects of the frequency of knowledge of results (KR) on both generalized motor programs and parameters. Two experiments were conducted that compared two frequencies of KR in terms of generalized motor programs and parameters: (1) the first experiment compared the effects of KR frequency on generalized motor programs in the 100% and 50% groups; and (2) the second experiment compared the effects of reduced KR frequency on parameters in the 100% and 50% groups. In the first experiment, results showed that the 50% group exhibited smaller relative timing errors than did the 100% group, but absolute timing errors in the transfer test were similar between these two groups. In the second experiment, both groups exhibited similar relative and absolute timing errors. These results suggested that the beneficial effects of reduced KR frequency were restricted to generalized motor programs.

Effects of mental practice in novice learners in a serial positioning skill acquisition.

The effects of mental practice in novices were investigated. University students (N = 60) performed a serial aiming task, distributed in 5 groups of 12: mental practice, physical practice, mental-physical practice (first mental then physical practice), physical-mental practice (first physical then mental practice), and a control group that only performed the tests. Participants transported three tennis balls among six containers in a pre-established sequence in a target time. In the acquisition phase and retention test (24 hr. later), the task was the same; in the transfer test, 5 min. after the acquisition phase, sequence and time changed. Six trials were performed in the acquisition phase, and each test consisted of 9 trials. The performance measures were absolute error, constant error, and variable error; a t test and a two-way ANOVA were used to compare the acquisition phase and tests, respectively. Physical practice and both groups of combined conditions presented better performance in tests than the mental practice and control groups. Mental practice without motor experience in the task did not improve motor learning. Prior physical performance is desirable before conducting mental practice.

Bandwidth knowledge of results on the learning of the saloon dart throwing task.

The effects of two different bandwidths of information of Knowledge of Results (KR) were investigated. 54 university students participated. The experiment consisted of an acquisition phase with practice of throwing a saloon dart as accurately as possible at a target lying on the floor 2.5 meters away until a specific area of the target was hit three trials in a row. Narrow bandwidth and Wide bandwidth groups received KR when performance was outside the bandwidth. A Control group received KR after every trial. A transfer test was run 10 min. later with 10 more trials and the target 3.0 m away, with no KR. Analyses showed that narrow KR bandwidth was associated with better learning of real world tasks.

An adaptive process model of motor learning: insights for the teaching of motor skills.

This article presents an outline of a non-equilibrium model, in which motor learning is explained as a continuous process of stabilization and adaptation. The article also shows how propositions derived from this model have been tested, and discusses possible practical implications of some supporting evidence to the teaching of motor skills. The stabilization refers to a process of functional stabilization that is achieved through negative feedback mechanisms. Initially, inconsistent and incorrect responses are gradually reduced, leading to a spatial-temporal patterning of the action. The adaptation is one in which new skills are formed from the reorganization of those already acquired through the flexibility of the system, reorganization of the skill structure, or self-organization. In order to provide learners with competency for adaptation, teachers should (a) guide students to learn motor skills taking into account that the stabilization of performance is just a transitory state that must be dismantled to achieve higher levels of complexity; (b) be clear which parts (micro) compose the skills and how they interact in order to form the whole (macro); (c) manipulate the skills in terms of their temporal, spatial, and/or spatiotemporal dimensions; (d) organize practice initially in a constant way, and then in a varied regimen (random) when the motor skills involve requirements of time and force; and, inversely for motor skills with spatial demands; and (e), provide a moderate frequency of feedback.

Combination of narrow and wide bandwidth knowledge of performance in the acquisition of a complex sports motor skill.

OBJECTIVES: This study tested the effects of combining two bandwidth knowledge of performance (KP) on a complex sports motor skill. METHOD: Twenty-two elementary students were divided into combined wide and narrow bandwidth KP (WNG) and control group (CG). The task was the volleyball serve, whose goal was to hit the bull's eye center of a target lying on the floor on the opposite side of the court. The study was composed of a pre-test, acquisition phase and retention test, and had three measures (pre-test, intermediate test, and retention test) with 15 serves recorded each. The acquisition phase consisted of 252 trials. The WNG had a wide bandwidth KP in the first half of the acquisition phase and a narrow one in the second. The CG received KP in all trials. The effects of bandwidth KP were analyzed separately to infer parameters and skill structure learning. RESULTS: Both groups improved the skill structure from the first to the intermediate test, but only WNG also improved on the retention test. The parameters accuracy improved only on retention compared to the pre-test and intermediate test but had no difference between groups. CONCLUSION: Providing information using the bandwidth KP led to an initial engagement and prioritization of skill structure learning.

Executive Functions and Motor Adaptation to Predictable and Unpredictable Perturbations.

In this study, we aimed to investigate the influence of executive functions (EF) on motor adaptation. We compared the motor performance of adults with and without EF deficits. Those with EF deficits (n = 21) were individuals with attention deficit hyperactivity disorder (ADHD) under medical treatment, and those without EF deficits (n = 21) comprised a control group (CG) of participants who were also without neurological or psychiatric diagnoses. Both groups performed a complex coincident timing motor task and various computerized neuropsychological tests for assessing EF. To investigate motor adaptation, the motor task provided measures of absolute error (AE) and variable error (VE) to reflect, respectively, performance accuracy and consistency relative to the task goal. We used reaction time (RT) to measure planning time taken before starting the task. First, participants practiced until they reached a criterion of performance stabilization (prior to their exposure to motor perturbations). They were next exposed to fast and slow predictable and unpredictable perturbations. On all neuropsychological tasks, participants with ADHD scored more poorly than control participants (p < .05); participants with ADHD also performed worse than control participants on all motor measures, particularly under unpredictable perturbations (p < .05). Under slow perturbations, EF deficits, particularly attentional impulsivity, negatively affected motor adaptation while cognitive flexibility was related to performance improvement. Under fast perturbations, both impulsivity and fast reaction time were related to improvement in motor adaptation under both predictable and unpredictable perturbations. We discuss the research and practical implications of these findings.

Effects of knowledge of results (KR) frequency in the learning of a timing skill: absolute versus relative KR frequency.

The interaction between the amount of practice and frequency of Knowledge of Results (KR) was investigated in a timing skill. In the acquisition phase the task involved 90 trials of releasing a knob and transporting three tennis balls from three near recipients to three far ones in a specific sequence and target time. The retention test performed 24 hr. later had the same sequence of transport but a new target time was required. In both phases, absolute error and standard deviation plus constant error was measured. The five groups differed in relation to frequency of KR and amount of practice. The results showed that intermediate frequencies as well as higher frequencies of KR elicited better performance during the retention test.

Burnout and Coping Perceptions of Volleyball Players Throughout an Annual Sport Season.

Burnout is a psychological syndrome of reaction to chronic stress that occurs in athletes who feel exhausted by a sport activity that was previously pleasurable and enjoyable. One technique to prevent and control the syndrome is through coping, which is the ability to deal with stressful situations. In contrast to traditional cross-sectional approaches, this study aimed to investigate burnout and coping strategy characteristics over time and to analyze the relationship between burnout dimensions and coping strategies. Fifty-four high-level volleyball athletes (twenty-eight men and twenty-six women, age M = 25.57, SD = 4.72, range 18-35) completed paper-and-pencil measures of burnout and coping four times throughout a sport season. The Friedman test presented a significant increase in the reduced sense of athletic accomplishment (X2 = 20.58; p < 0.01) and sport devaluation (X2 = 19.83; p < 0.01) perceptions during the season. However, no coping differences were observed through the longitudinal analysis. Burnout dimensions showed a moderate inverse correlation to confidence/motivation at all measurement points during the season. Overall, the findings suggest that burnout perceptions increase as the season progresses, highlighting the relevance for the periodization of burnout prevention and control.

Motor competence in fundamental motor skills and sport skill learning: Testing the proficiency barrier hypothesis.

We investigated whether motor competence in fundamental motor skills influences sports motor skill learning. Motor competence in fundamental motor skills related to the overhead volleyball serve (i.e., throwing and volleying) was evaluated in 38 children (aged 9-10 yrs) and participants were divided into lower and higher motor competence groups. The groups practiced the volleyball serve under random or constant-random conditions during an acquisition phase and then assessed in pre-test, intermediate, and retention tests. A three-way repeated-measures ANOVA showed performance improvement from pre-test to retention test only for high motor competence groups in fundamental motor skills. Initial competence in fundamental motor skills influences sport skills learning and demonstrates a potential proficiency barrier to learning complex-sports motor skills.

Enhanced Performance Stabilization Increases Performance Variability in a Virtual Interception Task.

Performing a motor task depends on the level of performance stabilization and movement control, and both aspects of motor behavior are related to motor learning (retention and transfer) and adaptation (predictable and unpredictable perturbations). Yet few studies have further investigated the underlying dynamics that may elicit these benefits. In this study, we investigated the effects of two levels of performance stabilization on motor performance and control while learning to intercept a virtual moving target. We randomly divided 40 participants of both sexes (Mage = 26.02 years, SD = 2.02) into a Stabilization Group (SG) and a Superstabilization Group (SSG). We considered the performance stabilized when a moving target was intercepted three times in a row and superstabilized when the same criterion was repeated six times. We analyzed outcome variables related to performance accuracy (absolute spatial error) and variability(coefficient of variation) and motor control (relative time to peak velocity-tPV% and its coefficient of variation) on both the first and last blocks of practice trials. Both groups showed comparable increases in performance accuracy from the first to the last block (p = .001, ηp2 = 1.00), but SSG presented higher variability than SG (p = .05, ηp2 = .70). Concerning motor control, both groups started the experiment with low tPV% and finished with comparably high tPV% and variability. Thus, although practicing two levels of performance stabilization led to similar performance accuracy and movement control, superstabilization resulted in higher performance variability with no loss of accuracy. Enhanced stabilization may increase the ability to adapt to environmental changes, but more research is needed to demonstrate this. These findings add to an understanding of the relationship between levels of performance stabilization and performance variability and may have implications for professional interventions (e.g. sports, rehabilitation) in considering the benefits of practice beyond performance stabilization.

Effect of bandwidth knowledge of results on the learning of a grip force control task.

An experiment was conducted to investigate the persistence of the effect of "bandwidth knowledge of results (KR)" manipulated during the learning phase of performing a manual force-control task. The experiment consisted of two phases, an acquisition phase with the goal of maintaining 60% maximum force in 30 trials, and a second phase with the objective of maintaining 40% of maximum force in 20 further trials. There were four bandwidths of KR: when performance error exceeded 5, 10, or 15% of the target, and a control group (0% bandwidth). Analysis showed that 5, 10, and 15% bandwidth led to better performance than 0% bandwidth KR at the beginning of the second phase and persisted during the extended trials.

Controlling Degrees of Freedom in Learning a Taekwondo Kick.

To test Bernstein's degrees of freedom (DF) hypothesis, the authors analyzed the effect of practice on the DF control and interjoint coordination of a Taekwondo kick. Thirteen inexperienced and 11 expert Taekwondo practitioners were evaluated. Contrary to Bernstein's hypothesis, the inexperienced group froze the DF at the end of learning, reducing the joint range of motion of the knee. Moderate and strong cross-correlations between joints did not change, demonstrating that the interjoint coordination was maintained. The inexperienced group's movement pattern was similar to that of the group of experts, from the beginning of the learning process. Thus, even after years of practice, experts continue to explore the strategy of freezing DF. The DF freeing/freezing sequence strategy was explored during the learning process, suggesting that DF-freezing/freeing strategies are task dependent.

Freezing Degrees of Freedom During Motor Learning: A Systematic Review.

According to Bernstein, the central nervous system solution to the human body's enormous variation in movement choice and control when directing movement-the problem of degrees of freedom (DF)-is to freeze the number of possibilities at the beginning of motor learning. However, different strategies of freezing DF are observed in literature, and the means of selection of the control strategy during learning is not totally clear. This review investigated the possible effects of the class and objectives of the skill practiced on DF control strategies. The results of this review suggest that freezing or releasing the DF at the beginning of learning does not depend on the class (e.g., discrete skill class: football kick, dart throwing; continuous skill class: athletic march, handwriting) or objective of the skill (e.g., balance, velocity, and accuracy), in isolation. However, an interaction between these two skill elements seems to exist and influences the selection of the DF control strategy.

Cathodal tDCS of the Left Posterior Parietal Cortex Increases Proprioceptive Drift.

In aiming movements the limb position drifts away from the defined target after some trials without visual feedback, a phenomenon defined as proprioceptive drift (PD). There are no studies investigating the association between the posterior parietal cortex (PPC) and PD in aiming movements. Therefore, cathodal and sham transcranial direct current stimulation (tDCS) were applied to the left PPC concomitantly with the performance of movements with or without vision. Cathodal tDCS applied without vision produced a higher level of PD and higher rates of drift accumulation while it decreased peak velocity and maintained the number of error corrections, not affecting movement amplitude. The proprioceptive information seems to produce an effective reference to movement, but with PPC stimulation it causes a negative impact on position.

Oculomotor behavior and the level of repetition in motor practice: Effects on pupil dilation, eyeblinks and visual scanning.

The benefits of less repetitive practice in motor learning have been explained by the increased demand for memory processes during the execution of motor skills. Recently, a new perspective associating increased demand for perception with less repetitive practice has also been proposed. Augmented information gathering and visual scanning characterize this higher perceptual demand. To extend our knowledge about mental effort and perceptual differences in practice organization, the association between oculomotor behavior and type of practice was investigated. We required participants to press four keys with different absolute and relative timing goals during the acquisition phase. An eye-tracker captured visual scanning of the skill's absolute and relative information displayed on the screen. Participants were tested 24 h after acquisition by a retention and transfer test. A higher level of both pupil dilation and amount of eyeblinks indicated an increased mental effort in less repetitive practice compared to more repetitive practice. Visual scanning of the skill's relative and absolute information was specific to the type of practice. The findings indicate many differences in oculomotor behavior associated with the practice schedule.

Self-Controlled Feedback and Learner Impulsivity in Sequential Motor Learning.

Many studies have attributed self-controlled feedback benefits associated with motor learning to learners' greater information processing during practice. However, individual learner characteristics like their impulsivity can also influence how people engage cognitively during learning. We investigated possible dissociations between the types of interaction in self-controlled knowledge of results (KR) and learner impulsivity levels in learning a sequential motor task. Ninety volunteers responded to the self-restraint section of the Barkley deficits in executive functioning scale, and those 60 participants with the highest ( n = 30) and lowest ( n = 30) impulsivity scores practiced a motor task involving sequential pressing of four keys in predetermined absolute and relative times. We further divided participants into four experimental groups by assigning the high- and low-impulsivity groups to two forms of KR-self-controlled absolute and yoked. Study results showed no interaction effect between impulsivity and self-controlled KR, and, contrary to expectation, self-controlled KR did not benefit learning, independently of impulsivity. However, low-impulsivity participants performed better than high-impulsivity participants on the absolute dimension of the transfer task, while high-impulsivity learners were better at the relative dimension. Cognitive characteristics of automatic and reflexive processing were expressed by the strategies used to direct attention to relative and absolute task dimensions, respectively. Low-impulsivity learners switched their attention to both dimensions at the end of practice, while high-impulsivity learners did not switch their attention or directed it only to the relative dimension at the end of the practice. These results suggest that the cognitive styles of high- and low-impulsive learners differentially favor learning distinct dimensions of a motor task, regardless of self-controlled KR.

Tactical Knowledge, Decision-Making, and Brain Activation Among Volleyball Coaches of Varied Experience.

This study compared decision-making (DM) of experienced and novice volleyball coaches while measuring blood flow brain activation with functional near-infrared spectroscopy. We sampled 34 coaches (mean [ M] age of 32.5, standard deviation [ SD] = 9.4 years) divided into two experience groups: (a) novice ( M = 2.8, SD = 1.9 years) and (b) experienced (M = 19, SD = 7.2 years). We evaluated coaches' DM through their responses to video-based scenarios of attacks performed in the extremities of the net within the Declarative Tactical Knowledge Test in Volleyball. We found no significant DM differences between the two groups of coaches ( p = .063), though novice (vs. experienced) coaches showed greater blood flow of the prefrontal cortex when visualizing the game situations. While experienced coaches may have better prefrontal neural efficiency during DM in these situations, further research is needed to evaluate other cerebral areas; since blood flow is an indirect measure of neural efficiency, and activity in remaining cortical components was unknown in this study.