A behavioural experiment in virtual reality to verify the role of action function in space coding

Neurophysiological data indicate that the reachable peripersonal space and the unreachable extrapersonal space are represented in segregated parietofrontal circuits and that when the unreachable space becomes reachable because of tool use, it is automatically coded by the network selective for peripersonal space. Here we directly tested the role of action's consequences in space coding. Thirty-eight participants bisected lines at either a reachable distance (60 cm) or unreachable distance (120 cm) using either a laser pointer or laser cutter. The laser cutter but not the laser pointer had an action consequence; the line broke into two pieces. The results showed that distance moderated the effect of action. At an unreachable distance, the mean bisection point was closer to the centre when participants used the laser cutter compared to when they used the laser pointer. There were no differences at a reachable distance (60 cm). This result suggests that the space in which the individual may determine a physical consequence is categorized as peripersonal space, independently from its actual distance from the individual's body.     

Correlation of motor skill,mental rotation,and working memory in 3- to 6-year-old children

A relationship between motor processes and mental rotation has been suggested by current research; however, the influence of working memory on this relationship has not yet been determined. Therefore, a correlation between motor tests, paper–pencil and chronometric mental rotation tests, and working memory tests were conducted in 3- to 6-year-old children. A stepwise multiple-regression showed that 55.5% of the variance was explained by the working memory tests: digit span forward and Corsi forward. This indicates that working memory and executive functions may play an important role in mental rotation and motor processes.     

Early and persistent motor difficulties in infants at-risk of developing autism spectrum disorder: A prospective study

Analyses were conducted in order to investigate motor development in younger siblings of children diagnosed with autism spectrum disorder (ASD). Infants at familial risk and low risk of developing ASD were tested longitudinally between the ages of 7 and 36 months. Data were analysed from motor scales on the Mullen Scales of Early Learning and the Vineland Adaptive Behaviour Scales at each age point. Significantly lower motor scores in at-risk infants were evident from the age of 7 months compared to the low-risk group. Infants who were later diagnosed with ASD demonstrated significantly poorer Fine Motor skills at 36 months than at-risk infants without any developmental difficulties. In addition, Gross Motor scores were highly correlated across the two measures for low-risk infants and infants who later developed ASD. Early motor difficulties may be an early indicator of a number of neurodevelopmental disorders, including ASD.     

Delayed auditory feedback in repetitive tapping: A role for the sensory goal

The open-loop model by Wing and Kristofferson has successfully explained many aspects of movement timing. A later adaptation of the model assumes that timing processes do not control the movements themselves, but the sensory consequences of the movements. The present study tested direct predictions from this “sensory-goals model”. In two experiments, participants were instructed to produce regular intervals by tapping alternately with the index fingers of the left and the right hand. Auditory feedback tones from the taps of one hand were delayed. As a consequence, regular intervals between taps resulted in irregular intervals between feedback tones. Participants compensated for this auditory irregularity by changing their movement timing. Compensation effects increased with the magnitude of feedback delay (Experiment 1) and were also observed in a unimanual variant of the task (Experiment 2). The pattern of effects in alternating tapping suggests that compensation processes were anticipatory—that is, compensate for upcoming feedback delay rather than being reactions to delay. All experiments confirmed formal model predictions. Taken together, the findings corroborate the sensory-goals adaptation of the Wing–Kristofferson model.     

Fundamental motor skill,physical activity,and sedentary behavior in socioeconomically disadvantaged kindergarteners

Guided by Stodden et al’s conceptual model, the main purpose of the study was to examine the relation between fundamental motor skills (FMS; locomotor and objective control skills), different intensity levels of physical activity (light PA [LPA], moderate-to-vigorous PA [MVPA], and vigorous PA[VPA]), and sedentary behavior (SB) in socioeconomically disadvantaged kindergarteners. A prospective design was used in this study and the data were collected across the 2013–2014 academic school year. Participants were 256 (129 boys; 127 girls; M_age = 5.37, SD = 0.48) kindergarteners recruited from three public schools in the southern United States. Results found that FMS were significantly related to LPA, MVPA, VPA, and SB. Regression analyses indicate that locomotor skills explained significant variance for LPA (6.4%; p < .01), MVPA (7.9%; p < .001), and VPA (5.3%; p < .01) after controlling for weight status. Mediational analysis supports the significant indirect effect of MVPA on the relation between FMS and SB (95% CI: [?0.019, ?0.006]). Adequate FMS development during early childhood may result in participating in more varied physical activities, thus leading to lower risk of obesity-related behaviors.     

Construct validity of the pictorial scale of Perceived Movement Skill Competence

ObjectivesThe Pictorial Scale of Perceived Movement Skill Competence (PMSC) assesses young children's perceptions of movement skill competence: 12 perceived Fundamental Movement skills (FMS; based on the Test of Gross Motor Development 2nd edition TGMD-2) and six Active Play activities (e.g. cycling). The main study purpose was to assess whether children's movement perception scores fit within the imposed constructs of Active Play and FMS by testing the latent structure and construct validity of the PMSC.DesignConstruct validation study.MethodsParticipants were part of the Melbourne Infant Feeding, Activity and Nutrition Trial (InFANT). The latent structure of the PMSC responses was tested through confirmatory factor analysis (CFA) and Bayesian Structural Equation Modeling (BSEM). Internal consistency was conducted using polychoric correlation-based alphas.ResultsThe 303 children (boys 53.1%, n = 161) were aged 4–5 years (M = 4.7, SD = 0.46). The final model had an 18 item 3-factor solution with good fit indices (using CFA and BSEM). Factors were: Active Play (Bike, Board Paddle, Climb, Skate/Blade, Scooter, and Swim), Object Control – Hand Skills (Bounce, Catch, Hit, Throw), and FMS skills with a leg action (Gallop, Hop, Jump, Leap, Run, Step Slide, Kick, Roll). Alpha reliability values were: Active Play (0.78), Object Control-Hand Skills (0.76) and FMS-Dynamic Leg (0.84).ConclusionYoung children can distinguish between movement perceptions. The factors reflect the hypothesized structure in terms of FMS being distinguished from Active Play. Further research should investigate how and if these constructs change in children over time.     

Evidence of muscular adaptations within four weeks of barbell training in women

We investigated the time course of neuromuscular and hypertrophic adaptations associated with only four weeks of barbell squat and deadlift training. Forty-seven previously untrained women (mean ± SD, age = 21 ± 3 years) were randomly assigned to low volume training (n = 15), moderate volume training (n = 16), and control (n = 16) groups. The low and moderate volume training groups performed two and four sets, respectively, of five repetitions per exercise, twice a week. Testing was performed weekly, and included dual X-ray absorptiometry and vastus lateralis and rectus femoris B-mode ultrasonography. Bipolar surface electromyographic (EMG) signals were detected from the vastus lateralis and biceps femoris during isometric maximal voluntary contractions of the leg extensors. Significant increases in lean mass for the combined gynoid and leg regions for the low (+0.68 kg) and moderate volume (+0.47 kg) groups were demonstrated within three weeks. Small-to-moderate effect sizes were shown for leg lean mass, vastus lateralis thickness and pennation angle, and peak torque, but EMG amplitude was unaffected. These findings demonstrated rapid muscular adaptations in response to only eight sessions of back squat and deadlift training in women despite the absence of changes in agonist–antagonist EMG amplitude.     

Adaptation of lower limb movement patterns when maintaining performance in the presence of muscle fatigue

Adaptations in lower limb movement patterns were examined when performance was maintained during a fatiguing repetitive loading task. Forty recreationally active male and female participants performed single-leg hopping to volitional exhaustion at 2.2 Hz to a submaximal height. Spatio-temporal characteristics, mechanical characteristics and variability of the knee-ankle and hip-knee joint couplings were determined at 20% increments during the duration of the hopping task. Variability of the knee-ankle and hip-knee couplings in the flexion/extension axis significantly increased during the loading and propulsion phases during the hopping task (p < 0.05). Performance (vertical stiffness, hopping frequency and height) did not change significantly during the task (p > 0.05), however foot contact time increased progressively during this task (p < 0.05) and maximum hop height significantly decreased after the task (p < 0.05). The observed increase in variability between adjoining lower limb segments demonstrated the ability of the neuromotor system to adapt and maintain performance even with the onset of fatigue. This finding highlights that during the performance of a rapid and repetitive loading activity, performance can be preserved when there is variability in the neuromotor system.