Is imagery better than reality? Performance in imagined dart throwing

We investigated whether deviations from optimal performance are predicted in motor imagery. In Experiment 1, novices and experts imagined and executed dart throws. In imagination, they reported the final position of the dart. Experts performed better than novices in execution and imagination. Distance to the target and bias were smaller in imagination than in execution. In Experiment 2, we dissociated the roles of feedback from proximal and distal action elements for predictions. Three groups of novices estimated the dart’s final position in imagination, in execution without visual feedback, or in execution with delayed visual feedback. Estimates did not differ significantly between groups, indicating that (the lack of) feedback did not influence predictions. Deviations from optimal performance were lower in estimated than in actual performance. In conclusion, although predictive mechanisms may be similar in imagination and execution, the full extent of deviation from optimal performance is not predicted.     

An examination of muscle force control in individuals with a functionally unstable ankle

Previous studies suggest that functional ankle instability (FAI) may be associated with deficits in the ability to sense muscle forces. We tested individuals with FAI to determine if they have reduced ability to control ankle muscle forces, which is a function of force sense. Our test was performed isometrically to minimize the involvement of joint position sense and kinesthesia. A FAI group and a control group were recruited to perform an ankle force control task using a platform-based ankle robot. They were asked to move a cursor to hit 24 targets as accurately and as fast as possible in a virtual maze. The cursor movement was based on the direction and magnitude of the forces applied to the robot. Participants underwent three conditions: pre-test (baseline), practice (skill acquisition), and post-test (post skill acquisition). The force control ability was quantified based on the accuracy performance during the task. The accuracy performance was negatively associated with the collision count of the cursor with the maze wall. The FAI group showed reduced ability to control ankle muscle forces compared to the control group in the pre-test condition, but the difference became non-significant in the post-test condition after practice. The change in performance before and after practice may be due to different degrees of reliance on force sense.     

Fractal properties and short-term correlations in motor control in cycling: influence of a cognitive challenge

Fluctuations in cyclic tasks periods is a known characteristic of human motor control. Specifically, long-range fractal fluctuations have been evidenced in the temporal structure of these variations in human locomotion and thought to be the outcome of a multicomponent physiologic system in which control is distributed across intricate cortical, spinal and neuromuscular regulation loops.Combined with long-range correlation analyses, short-range autocorrelations have proven their use to describe control distribution across central and motor components.We used relevant tools to characterize long- and short-range correlations in revolution time series during cycling on an ergometer in 19 healthy young adults. We evaluated the impact of introducing a cognitive task (PASAT) to assess the role of central structures in control organization.Autocorrelation function and detrending fluctuation analysis (DFA) demonstrated the presence of fractal scaling. PSD in the short range revealed a singular behavior which cannot be explained by the usual models of even-based and emergent timing.The main outcomes are that (1) timing in cycling is a fractal process, (2) this long-range fractal behavior increases in persistence with dual-task condition, which has not been previously observed, (3) short-range behavior is highly persistent and unaffected by dual-task.Relying on the inertia of the oscillator may be a way to distribute more control to the periphery, thereby allocating less resources to central process and better managing additional cognitive demands. This original behavior in cycling may explain the high short-range persistence unaffected by dual-task, and the increase in long-range persistence with dual-task.     

Breastfeeding and motor development: A longitudinal cohort study

BackgroundWhile there is a large body of work supporting the importance of early feeding practices on cognitive, immunity, behavioural and mental outcomes, few longitudinal studies have focused on motor development. The relationship between duration of breast feeding and motor development outcomes at 10, 14, and 17 years were examined.MethodsData were obtained from the Western Australian Pregnancy (Raine) Study. There were 2868 live births recorded and children were examined for motor proficiency at 10 (M = 10.54, SD = 2.27), 14 (M = 14.02, SD = 2.33) and 17 (M = 16.99, SD = 2.97) years using the McCarron Assessment of Neuromuscular Development (MAND). Using linear mixed models, adjusted for covariates known to affect motor development, the influence of predominant breast feeding for <6 months and ⩾6 months on motor development outcomes was examined.ResultsBreast feeding for ⩾6 months was positively associated with improved motor development outcomes at 10, 14 and 17 years of age (p = 0.019, β 1.38) when adjusted for child’s sex, maternal age, alcohol intake, family income, hypertensive status, gestational stress and mode of delivery.ConclusionEarly life feeding practices have an influence on motor development outcomes into late childhood and adolescence independent of sociodemographic factors.     

Motor expertise and performance in spatial tasks: A meta-analysis

The present study aimed to provide a summary of findings relevant to the influence of motor expertise on performance in spatial tasks and to examine potential moderators of this effect. Studies of relevance were those in which individuals involved in activities presumed to require motor expertise were compared to non-experts in such activities. A final set of 62 effect sizes from 33 samples was included in a multilevel meta-analysis. The results showed an overall advantage in favor of motor experts in spatial tasks (d = 0.38). However, the magnitude of that effect was moderated by expert type (athlete, open skills/ball sports, runner/cyclist, gymnast/dancers, musicians), stimulus type (2D, blocks, bodies, others), test category (mental rotation, spatial perception, spatial visualization), specific test (Mental Rotations Test, generic mental rotation, disembedding, rod-and-frame test, other), and publication status. These findings are discussed in the context of embodied cognition and the potential role of activities requiring motor expertise in promoting good spatial performance.     

Prediction of calcaneal bone competence from biomechanical accommodation variables measured during weighted walking

Carrying weight while walking is a common activity associated with increased musculoskeletal loading, but not all individuals accommodate to the weight in the same way. Different accommodation strategies could lead to different skeletal forces, stimuli for bone adaptation and ultimately bone competence. The purpose of the study was to explore the relationships between calcaneal bone competence and biomechanical accommodation variables measured during weighted walking. Twenty healthy men and women (10 each; age 27.8 ± 6.8 years) walked on a treadmill at 1.34 m/s while carrying 0, 44.5 and 89 N weights with two hands in front of the body. Peak vertical ground reaction force and sagittal plane angular displacements of the trunk and left lower extremity during weight acceptance were measured and used to quantify accommodation. Calcaneal bone stiffness index T-score (BST) was measured using quantitative ultrasound. Correlation and stepwise multiple regression were used to predict calcaneal BST from the accommodation variables. Accommodations of the foot and ankle explained 29 and 54% (p ≤ .015) of the variance in calcaneal BST in different regression models. Statistical resampling using 1000 replications confirmed the strength and consistency of relationships, with the best model explaining 94% of the variance in calcaneal BST. Individuals who change foot and ankle function when carrying heavier weight likely alter the control of gravitational and muscular forces, thereby affecting calcaneal loading, bone adaptation and bone competence. These novel findings illustrate the importance of gait accommodation strategies and highlight a potential clinical consequence that requires further investigation.     

“Pushing the Button While Pushing the Argument”: Motor Priming of Abstract Action Language

In a behavioral study we analyzed the influence of visual action primes on abstract action sentence processing. We thereby aimed at investigating mental motor involvement during processes of meaning constitution of action verbs in abstract contexts. In the first experiment, participants executed either congruous or incongruous movements parallel to a video prime. In the second experiment, we added a no‐movement condition. After the execution of the movement, participants rendered a sensibility judgment on action sentence targets. It was expected that congruous movements would facilitate both concrete and abstract action sentence comprehension in comparison to the incongruous and the no‐movement condition. Results in Experiment 1 showed a concreteness effect but no effect of motor priming. Experiment 2 revealed a concreteness effect as well as an interaction effect of the sentence and the movement condition. The findings indicate an involvement of motor processes in abstract action language processing on a behavioral level.     

我对卒中单元的体会

卒中单元作为卒中治疗的最佳模式,逐渐被临床医生所接受,就卒中单元的概念、特点及我国卒中的现状等多数人所关心的问题进行了分析和探讨,以助于更好的理解。     

建立有中国特色的卒中单元

卒中单元是一种医疗管理模式,它将治疗脑卒中的有效手段集中在一起,让病人在有效治疗时间窗内的到他所需要的最佳治疗,尽可能地使卒中病人恢复神经功能,恢复自我,回归社会。但我国的卒中单元还存在许多问题,需共同努力建立有中国特色的卒中单元。