Subsequent Motor Performance Research Articles

Multi-objective optimization design of electric vehicle in-wheel motor based on Taguchi method

In order to solve the problem of motor performance degradation caused by torque ripple and large cogging torque of in-wheel permanent magnet synchronous motor for electric vehicles, Taguchi is used to optimize the magnetic pole of built-in Permanent magnet synchronous motor, and the orthogonal optimization matrix of magnetic pole parameters is established. Through the parameter optimization matrix, the workload of pole optimization is reduced and the optimization speed is improved. The optimization results show that the orthogonal matrix optimization can not only improve the output torque of permanent magnet synchronous motor, but also further control its torque ripple and cogging. The orthogonal matrix optimization method used in this paper for V-I type built-in permanent magnet synchronous motor has a certain positive significance, and provides a certain reference value for the subsequent motor performance optimization.

Impact of decision and action outcomes on subsequent decision and action behaviours in humans.

Speed-accuracy trade-off adjustments in decision-making have been mainly studied separately from those in motor control. In the wild, however, animals coordinate their decision and action, often deciding while acting. Recent behavioural studies support this view, indicating that animals, including humans, trade decision time for movement time to maximize their global rate of reward during experimental sessions. Besides, it is well established that choice outcomes impact subsequent decisions. Crucially though, whether and how a decision outcome also influences the subsequent motor performance, and whether and how the outcome of a movement influences the next decision, is unclear. Here, we address these questions by analysing trial-to-trial changes of choice and motor behaviours in healthy human participants instructed to perform successive perceptual decisions expressed with reaching movements whose duration was either weakly or strongly constrained in separate tasks. Results indicate that after a wrong decision, subjects who were weakly constrained in their action duration decided more slowly and more accurately. Interestingly, they also shortened their subsequent movement duration by moving faster. Conversely, we found that errors of constrained movements influenced not only the speed and the amplitude of the following movement but those of the decision too. If the movement had to be slowed down, the decision that precedes that movement was accelerated and vice versa. Together, these results indicate that from one trial to the next, humans seek to determine a behavioural duration as a whole instead of optimizing each of the decision and action speed-accuracy trade-offs independently of each other.

Identifying the Optimal Arm Priming Exercise Intensity to Improve Maximal Leg Sprint Cycling Performance.

Priming exercises improve subsequent motor performance; however, their effectiveness may depend on the workload and involved body areas. The present study aimed to estimate the effects of leg and arm priming exercises performed at different intensities on maximal sprint cycling performance. Fourteen competitive male speed-skaters visited a lab eight times, where they underwent a body composition measurement, two V̇O2max measurements (leg and arm ergometers), and five sprint cycling sessions after different priming exercise conditions. The five priming exercise conditions included 10-minute rest (Control); 10-minute arm ergometer exercise at 20% V̇O2max (Arm 20%); 10-minute arm ergometer exercise at 70% V̇O2max (Arm 70%); 1-min maximal arm ergometer exercise at 140% V̇O2max (Arm 140%); and 10-min leg ergometer exercise at 70% V̇O2max (Leg 70%). Power outputs of 60-s maximal sprint cycling, blood lactate concentration, heart rate, muscle and skin surface temperature, and rating of perceived exertion were compared between the priming conditions at different measurement points. Our results showed that the Leg 70% was the optimal priming exercise among our experimental conditions. Priming exercise with the Arm 70% also tended to improve subsequent motor performance, while Arm 20% and Arm 140% did not. Mild elevation in blood lactate concentration by arm priming exercise may improve the performance of high-intensity exercise.

Effect of a sex stereotype on cortical activity during a self-paced exercise: A motor-related cortical potential approach

Recent research has shown that inducing a negative stereotype toward women does not always decrease the subsequent motor performance of women, but can increase it, especially during endurance tasks. The mechanisms involved are nonetheless still poorly understood. The main aim of the present study was to investigate the effect of a negative stereotype toward women on men’s and women’s performance during an endurance task, and to analyze the neuropsychological mechanisms involved through motor-related cortical potentials and motivation toward men/women. Thirty-four participants were assigned to a negative stereotype toward women condition and a nullified-stereotype condition and performed 80 self-paced intermittent isometric elbow contractions at a moderate perceived intensity. Results showed that women performed better when assigned to the negative stereotype toward women condition, they were more motivated to outperform men, and their MRCP amplitudes were higher in this same condition over the prefrontal cortex (i.e., FP1 and FP2). Concerning men, they also performed better when the negative stereotype toward women was induced. However, no effect emerged on motivation toward women and MRCP amplitudes. This study showed that inducing a negative stereotype during an endurance task led to a performance increase in women, which is contrary to the stereotype threat theory, strengthening the idea of a task-dependency effect when inducing a negative stereotype. This performance improvement observed in women may be caused by increased motivation to outperform men and a planning of the upcoming movement. Concerning men, more research is needed to clarify the mechanisms involved in such performance improvement.

Association of the Onset of Self-Feeding With Subsequent Suspected Developmental Coordination Disorder: A Prospective Cohort Study in China.

BackgroundSuccessful self-feeding reflects the readiness of early motor development and environmental impacts, and the onset of self-feeding as a developmental milestone might be a predictor of subsequent motor development in children. In this study, we explored the association between the onset of self-feeding and childhood risk of Developmental Coordination Disorder in children from one-child and two-child families.MethodsWe conducted a data-linkage prospective cohort study from 38 kindergartens in 6 cities in China. A total of 11,727 preschoolers aged 3–6 years old were included in the final analysis and were assessed with the Movement Assessment Battery for Children-second edition (MABC-2) Test. The information on early self-feeding onset was obtained from parents. The mixed and multi-level logistic models utilizing a random intercept were used to investigate the associations between the onset time of self-feeding and subsequent motor performance.ResultsThe results showed that, compared with those beginning self-feeding at or younger than 12 months of age, children starting self-feeding at 13–24, 25–36, and later than 36 months, showed a decrease in their total MABC-2 scores of 2.181, 3.026, and 3.874, respectively; and had an increased risk of suspected DCD by 36.0, 101.6, 102.6%, respectively; they also had 30.2, 46.6, 71.2% increased prevalence of at risk of suspected DCD, when adjusting for both child and family characteristics (each p < 0.05). Significant associations were observed in fine motor, gross motor, and balance subtests (each p < 0.05) in groups with a delayed onset of self-feeding. However, the strength of the associations was mitigated in the fine motor and balance subtests in children with a sibling.ConclusionThe delayed onset time of self-feeding acts as an early behavioral marker for later childhood motor impairment. Moreover, children with a sibling may benefit from additional interaction and their motor developmental pattern may be affected by the presence of a sibling.

Does the Simon Effect Interfere with the Synergy Between Perception and Action?

Research suggests that - particularly - the execution of precision-demanding far-aiming tasks necessitates an optimal coupling between perception and action. In this regard, the duration of the last fixation before initiating movement - i.e., the Quiet Eye (QE) - has been functionally related to subsequent motor performance. In the current study, we investigated potential mechanisms of QE by applying the Simon paradigm - i.e., cognitive interferences evoked by stimulus-effect incompatibilities over response selection. To this end, we had participants throw balls as precisely as possible, either with their left or right hand (hands condition, HC) or at left or right targets (targets condition, TC), respectively. Via monaural auditory stimuli, participants received information about the hand side and the target side, respectively, either with compatible (i.e., congruent stimulus-effect side) or incompatible (i.e., incongruent stimulus-effect side) stimulus-effect mappings. Results showed that participants reacted slower and showed later first fixation onsets at the target in incompatible vs. compatible trials, thus, replicating and extending the classical Simon effect. Crucially, in the HC, there were earlier QE onsets and longer QE durations in incompatible (vs. compatible) trials, suggesting an inhibition of cognitive interferences over response selection to preserve motor performance. These findings are in line with attentional explanations of QE, suggesting optimized attentional control with efficient management of limited cognitive resources (optimal-attentional-control explanation) or with the inhibition of alternative response parametrization (inhibition explanation).

Acute stress affects implicit but not explicit motor imagery: A pilot study

Motor imagery (MI) is the capacity to mentally perform one or a set of movements without concomitant overt action. MI training has been show to enhance the subsequent motor performance. While the benefits of MI to manage stress have been extensively documented, the reverse impact of stress on MI received far less attention. The present study thus aimed to evaluate whether acute stress might influence MI abilities. Thirty participants were assigned either to a stress or a control group. The Socially Evaluated Cold Pressor Test (SECPT) was used to induce stress, with heart rate, electrodermal activity, salivary cortisol, and self-report perceived levels of stress being monitored during the experiment. Stress induction was followed by both implicit (laterality judgment) and explicit (sequential pointing) MI tasks. Main results showed a deleterious impact of stress on implicit MI, while explicit MI was not altered. These exploratory findings provide a deeper understanding of stress effects on cognition, and practically support that under stressful conditions, as during a sport competition or rehabilitation contexts, explicit MI should be prioritized.

Moving Advertisements Systematically Affect Gaze Behavior and Performance in the Soccer Penalty Kick.

The aim of the current study was to investigate whether a moving advertisement positioned behind the goal area would influence the visual attention of participants performing a soccer penalty kick, and, whether this would an effect on subsequent motor performance. It was hypothesized that if the (moving) advertisement would function as a distractor, then this would result in non-specific disruptions in penalty performance measures, especially affecting aiming location and precision. Alternatively, it was reasoned that, in line with the Dunker illusion, the moving advertisement would systematically affect perception of target location, resulting in changes in penalty performance and aiming that are specific for the direction of motion of the advertisement. To test these hypotheses, we investigated the gaze behavior and kicking performance of intermediate skilled soccer players taking penalty kicks in three differing advertisement conditions, namely no advertisement, a stationary advertisement, and a moving advertisement. The latter condition consisted of an advertisement moving from left to right and an advertisement moving from right to left. Results showed that a moving advertisement placed behind the goal area indeed caught the visual attention of soccer penalty kickers using a goalkeeper-dependent kicking strategy. Participants kicking performance tended to be less variable within the no advertisement condition compared to the moving advertisement condition. In addition, systematic, direction-specific effects on aiming were found when comparing conditions in which the advertisement moved in opposite directions. This pattern of findings indicate that the accuracy of the penalty kick is impacted by task-irrelevant contextual information.

Somatosensory perceptual training enhances motor learning by observing.

Action observation activates brain regions involved in sensory-motor control. Recent research has shown that action observation can also facilitate motor learning; observing a tutor undergoing motor learning results in functional plasticity within the motor system and gains in subsequent motor performance. However, the effects of observing motor learning extend beyond the motor domain. Converging evidence suggests that observation also results in somatosensory functional plasticity and somatosensory perceptual changes. This work has raised the possibility that the somatosensory system is also involved in motor learning that results from observation. Here we tested this hypothesis using a somatosensory perceptual training paradigm. If the somatosensory system is indeed involved in motor learning by observing, then improving subjects' somatosensory function before observation should enhance subsequent motor learning by observing. Subjects performed a proprioceptive discrimination task in which a robotic manipulandum moved the arm, and subjects made judgments about the position of their hand. Subjects in a Trained Learning group received trial-by-trial feedback to improve their proprioceptive perception. Subjects in an Untrained Learning group performed the same task without feedback. All subjects then observed a learning video showing a tutor adapting her reaches to a left force field. Subjects in the Trained Learning group, who had superior proprioceptive acuity before observation, benefited more from observing learning than subjects in the Untrained Learning group. Improving somatosensory function can therefore enhance subsequent observation-related gains in motor learning. This study provides further evidence in favor of the involvement of the somatosensory system in motor learning by observing. NEW & NOTEWORTHY We show that improving somatosensory performance before observation can improve the extent to which subjects learn from watching others. Somatosensory perceptual training may prime the sensory-motor system, thereby facilitating subsequent observational learning. The findings of this study suggest that the somatosensory system supports motor learning by observing. This finding may be useful if observation is incorporated as part of therapies for diseases affecting movement, such as stroke.

Quiet Eye and Motor Performance: The Longer the Better?

The quiet-eye (QE) phenomenon has been found to predict subsequent motor performance. However, it remains unclear whether this effect also holds for considerably extended QE durations. Therefore, in 2 ball-throwing studies, QE durations of 400-3,200ms were experimentally induced. Inferior performance was found in short QE-duration conditions; however, there was no difference between the long QE-duration conditions. Extrapolations beyond the observed QE values showed performance gains up to 2,000ms and a shallow interval of optimality at a QE duration of about 3,000ms. These results, together with the fact that the intended absolute QE durations were not achieved, point toward an inhibition explanation of the QE. Thus, the initial performance gain is interpreted as shielding of the movement parameterization against suboptimal alternatives, whereas the performance loss due to very long QE durations is ascribed to mutually balancing the processes of shielding and environmental monitoring.

EP 118. Can midday naps boost learning in older adults?

Naps as well as a night of sleep were found to improve motor learning in young individuals (Doyon et al., 2009). The capacity of older adults to learn and stabilize motor memory traces (consolidation) during over-night sleep is limited (Pan and Rickard, 2015, Backhaus et al., 2015). However a small number of studies suggested sleep-dependent consolidation in healthy older adults, immediately after sleep (Gudberg et al., 2015, Al-Sharman and Siengsukon, 2014) or after a delayed period (Tucker et al., 2011, Korman et al., 2015). Can midday naps enhance motor learning in older adults? We evaluated the performance changes of a sample of thirty-three healthy older adults (60–82 years) by implementing a napping paradigm in a motor learning setup (sequence learning and motor adaption). The participants were randomly assigned to one of three groups; short nap group (a forty-five minutes nap opportunity, 10–20 min sleep), long nap group (ninety minutes nap opportunity, 50–80 min sleep) or a forty-five minutes period of wakefulness. Three learning sessions on two consecutive days were compared for both tasks with the repeated measures mixed model approach. All older adults were able to improve their task performance in both tasks throughout all sessions. For sequence learning no differences between the nap groups could be found following the midday nap, nor after an extended period of consolidation, i.e. the following day. Similarly no significant differences between the groups could be found directly after the midday break when performing the motor adaptation task. However during the final block of the last session nappers performed significantly better (p = 0.023) than those adults staying awake. Although midday naps may have a great recuperative value (Tamaki et al., 1999, Campbell et al., 2011), these effects could not be projected on motor learning and subsequent motor performance directly after napping. Based on the current results we conclude that short daytime naps do not enhance the effects of motor learning and consolidation. Thus, deficits in consolidation apparent in older adults are not dependent of the duration of sleep but rather of the process of consolidation during sleep, which seems to be impaired in older adults. This work was supported by the Stiftung der Deutschen Wirtschaft providing a PhD Scholarship to W.B. W.B and F.C.H. hold a research grant from the Werner-Otto-Foundation (9/87).

Perinatal MRI diffusivity is related to early assessment of motor performance in preterm neonates

Preterm neonates represent a high-risk population for abnormal neuropsychological development. But presently, an accurate method for identifying those at risk is not available. This study evaluated the association between the microstructural organization measured with Diffusion Tensor Imaging (DTI) in term-corrected preterm neonates and subsequent motor performance. Fractional anisotropy (FA), axial diffusion (AD), mean diffusivity (MD) and radial diffusivity (RD) were determined in two regions of interest (ROIs) corresponding to the posterior limb of the internal capsule (PLIC) and cortico-spinal tract (CST). The Griffiths Mental Developmental Scales (GMDS) were longitudinally administered at 3, 6 and 15 months; and correlations between the metrics of diffusivity and the motor subscale of the GMDS were assessed using the Spearman correlation. A statistically significant negative correlation was observed between the AD of PLIC of the left hemisphere and the 3-month GMDS Locomotor Subscale. These results suggested that AD is a valid indicator of the stage of maturation of the motor pathway in preterm neonates, but not of later motor outcome.

Perinatal factors in non‐disabled ELBW school children and later performance

To determine the association between perinatal events and subsequent motor performance, cardiorespiratory endurance and respiratory function in non-disabled extremely low birthweight (ELBW) school children at 12 years of age. Forty-eight ELBW infants were included in this study. The Movement Assessment Battery for Children (MABC), VO(2) max score as a measure of cardiorespiratory endurance and respiratory function testing were performed and perinatal variables were extracted from the children's hospital files. Children with MABC score ≤ 15th centile were described as having suspect motor performance. Children were classified as being unfit with a VO(2) max > 1 standard deviation below the mean according to gender and age. Perinatal risk factors were explored as risk factors for motor outcome, cardiorespiratory endurance and respiratory function. MABC category was significantly related with gender (P = 0.005) and chronic neonatal lung disease (P = 0.013). Multiple regression analysis showed motor outcome at 12 years to be independently related to male gender (P = 0.03) and chronic neonatal lung disease (P = 0.045). Sixty-five percent of all the children were identified as unfit. Chronic neonatal lung disease was significantly related to cardiorespiratory endurance (P = 0.03) and predicted VO(2) max at 12 years (P = 0.05). No perinatal factors were significantly related to respiratory function variables. Male gender and chronic neonatal lung disease were associated with later motor outcome of ELBW school children. It is suggested that objective and consistent follow-up from childhood through preadolescence are important to address motor and fitness issues especially for male children born with ELBW.

Commentary: From iodine deficiency in Papua New Guinea to a global programme of prevention

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Priming of Disability and Elderly Stereotype in Motor Performance: Similar or Specific Effects?

In three experimental studies, the effects of priming participants with the disability stereotype were investigated with respect to their subsequent motor performance. Also explored were effects of activating two similar stereotypes, persons with a disability and elderly people. In Study 1, participants were primed with the disability stereotype versus with a neutral prime, and then asked to perform on a motor coordination task. In Studies 2 and 3, a third condition was introduced: priming participants with the elderly stereotype. Results indicated that priming participants with the disability stereotype altered their motor performance: they showed decreased manual dexterity and performed slower than the non-primed participants. Priming with the elderly stereotype decreased only performance speed. These findings underline that prime-to-behavior effects may depend on activation of specific stereotype content.

The Relationship Between Behavior Ratings and Concurrent and Subsequent Mental and Motor Performance in Toddlers Born at Extremely Low Birth Weight

When predicting child developmental outcomes, reliance on children's scores on measures of developmental functioning alone might mask more subtle behavioral difficulties especially in children with developmental risk factors. The current study examined predictors and stability of examiner behavior ratings and their association with concurrent and subsequent mental and motor performance in toddlers born at extremely low birth weight. Toddlers were evaluated using the Behavior Rating scale (BRS) and the mental and psychomotor indexes of the Bayley-II at 18 and 30 months corrected age. BRS total and factor scores showed moderate stability between 18 and 30 months. These scores also predicted 30-month Mental Scale and Psychomotor Scale scores above and beyond prior mental and motor performance. Our findings suggest that early behavior ratings are associated with child mental and motor performance; therefore, behavior ratings might be useful in identifying toddlers at developmental risk and who might benefit from early intervention.

Circadian Modulation of Mentally Simulated Motor Actions: Implications for the Potential Use of Motor Imagery in Rehabilitation

Background. Mental practice through motor imagery improves subsequent motor performance and thus mental training is considered to be a potential tool in neuromotor rehabilitation. Objective. The authors investigated whether a circadian fluctuation of the motor imagery process occurs, which could be relevant in scheduling mental training in rehabilitation programs. Methods. The executed and imagined durations of walking and writing movements were recorded every 3 hours from 8 AM to 11 PM in healthy participants. The authors made a cosinor analysis on the temporal features of these movements to detect circadian rhythms. Temporal differences between executed and imagined movements as well as their variability during the day were also quantified. Results. Circadian rhythms were detected for both the executed and the imagined movements. Furthermore, these rhythms covaried between them and with body temperature. The participants' ability to internally simulate their movements also fluctuated significantly during the day. The isochrony between the executed and the imagined movements was exclusively observed between 2 PM and 8 PM. In the morning (8 AM and 11 AM) and the evening (11 PM), the durations of the imagined movements were significantly longer than the durations of executed movements. Conclusions . Predictive internal models fluctuate in a circadian basis, as do many other physiological parameters. It could be important to take into consideration the time of day in the planning of rehabilitation programs using physical or mental training.

Deep hypothermic circulatory arrest and the effects on the brain

This article reviews the effect of deep hypothermic circulatory arrest (DHCA) in children with congenital heart disease on subsequent cognitive and motor performance.

Increased behavioral neurosteroid sensitivity in a rat line selectively bred for high alcohol sensitivity

Acute administration of a neurosteroid 5β-pregnan-3α-ol-20-one induced a greater impairment in motor performance of the selectively bred alcohol-sensitive (ANT) than alcohol-insensitive (AT) rats. This difference was not associated with the sensitivity of γ-aminobutyrate type A (GABA A) receptors, as 5α-pregnan-3α-ol-20-one (allopregnanolone) decreased the autoradiographic signals of t-butylbicyclophosphoro[ 35S]thionate binding to GABA A receptor-associated ionophores more in the brain sections of AT than ANT rats. Nor was the difference associated with baseline levels of neuroactive progesterone metabolites, as 5α-pregnan-3,20-dione (5α-DHP) and 5α-pregnan-3α-ol-20-one were lower in the ANT rats. After ethanol (2 g/kg, i.p.) administration and the subsequent motor performance test, the increased brain concentrations of these metabolites were still lower in the ANT than AT rats, although especially in the cerebellum the relative increases were greater in the ANT than AT rats. The present data suggest that the mechanisms mediating neurosteroid-induced motor impairment are susceptible to genetic variation in rat lines selected for differences in ethanol intoxication.

The Relationship Between the Scarf Ratio and Subsequent Motor Performance in Infants Born Preterm

The relationship between the scarf ratio and subsequent motor performance in Thai infants born preterm was the focus of this study. The scarf ratio was measured in 61 infants at 36 and 40 weeks postconceptional age (PCA). At 40 weeks PCA, one-, two-, three-, and four-months adjusted age, the infants were evaluated using the Test of Infant Motor Performance. Pearson product moment correlations revealed significant positive correlations between the scarf ratio and the infants' later motor performance. Because the scarf ratio can be a useful measure of shoulder girdle muscle tone, it may provide a valuable indicator of subsequent motor performance in infants born preterm who might be considered to be at risk for developmental delay.