Journal of Motor Behavior最新文献

Proprioceptive inputs have crucial roles in control of the posture. The aim of the present study was to assess the effect of interfering with these signals on postural stability by ice-induced anaesthesia and local calf muscle fatigue. Seventeen healthy young individuals participated in this study to stand quietly and on an unstable platform under normal, anaesthesia, and fatigue conditions. A force platform calculated excursions of centre of pressure. Stabilogram-diffusion analysis was utilised to evaluate how body controls the posture with and without proprioceptive inputs. Time intervals of using the sensory feedback is significantly increased by anaesthesia in quiet standing (430 ms, p = 0.034) to note more delayed use of sensory information in a closed-loop. Additionally, fatigue significantly increased the time intervals of using sensory feedback during standing on the unstable platform (290 ms, p = 0.016). Interestingly, sensory interventions had no effect on the stability of the open-loop control of posture (short-term control), but they significantly influenced the closed-loop control (long-term control) (p < 0.004). Specifically, fatigue led to increased instabilities when the body used sensory inputs during both quiet standing (p = 0.021) and standing on the unstable platform (p = 0.041). These findings highlight the importance of proprioception in balance control for healthy individuals. Interfering with proprioceptive inputs, either through anaesthesia or fatigue, resulted in instabilities during balance maintenance. Our study provides new insights into the mechanisms underlying postural control, emphasising the significance of proprioceptive inputs. Understanding how proprioception affects balance maintenance may have implications for rehabilitation strategies, injury prevention, and the development of interventions to improve postural stability.

Researchers have investigated the sensorimotor mechanisms that result in Fitts' law. One approach has been to analyse movement trajectories during Fitts' tasks to reveal the processes that occur during movement preparation and execution. We used trajectory analysis in the current study to investigate how limb-target control contributed to Fitts' law during the transition from ballistic movements to movements with online control. Twenty-five participants made discrete reaching movements in seven conditions with indexes of difficulty that ranged from one to seven. There were strong linear relationships between index of difficulty, effective index of difficulty and movement time. Trajectory analysis suggested that the easiest condition had movements that were mostly ballistic. There was enough time for visual-based online corrections, but the condition was probably too easy to require limb-target control. Trajectory analysis also suggested that there was an increased reliance on limb-target control as the index of difficulty increased. In conclusion, there was a strong linear relationship between effective index of difficulty and movement time even with conditions that ranged from mostly ballistic to a high degree of limb-target control. We suggest that there is a direct relationship between effective index of difficulty and degree of limb-target control.

Cross-education (CE) is a phenomenon whereby motor training of one limb leads to improved performance in the opposite untrained limb. External pacing of a motor task can enhance CE; however, the influence of different pacing methods is poorly understood. This study explored how motor training with auditory (AP) and visual pacing (VP) impacts CE with a visuomotor force target task. Sixty-one participants performed a unimanual motor task. Participants were randomized into a visual (n = 31) or auditory (n = 30) pacing stimuli condition. The primary outcome was cumulative error scores for each hand, before and after visuomotor training. Pacing type did not yield different magnitudes of CE. However, after adjusting for baseline differences, a significant hand (trained vs. untrained) × practice side (dominant or non-dominant) interaction (p = .013, η_p² = .106) and a group main effect (p = .036, η_p² = .165) were observed. Visual pacing resulted in greater improvements in task performance compared to auditory pacing regardless of hand or practice side, while training the dominant limb resulting in a greater interlimb asymmetry regardless of pacing stimulus. These findings have implications for applying pacing strategies during rehabilitation from unilateral injury or neurological impairment.

Force perception (FP) is a sub-modality of proprioception, influenced by muscle mechanoreceptors. In studies on proprioception, joint position sense and kinesthesia are typically the primary focus, while research on FP remains comparatively limited. This study aimed to examine the effects of gender and maximal grip strength (MGS) on FP. To determine MGS, the participants first squeezed the dynamometer with the dominant hand, followed by non-dominant hand. FP was tested at 25% and 50% of the MGS. The participants were taught these target values using visual feedback displayed on a screen. Then, they were instructed to reproduce the learned grip force without visual input. The difference between the target value and the achieved value was noted as the Absolute Error (AE). A significant difference was observed between males and females in the AE at 25% of MGS. MGS was correlated with FP. Increased grip strength was correlated with greater errors in force reproduction. Overall, gender and hand dominance did not appear to have a significant effect on FP (except for the 25% AE). A clearer understanding of the effects of gender and MGS on FP could help healthcare professionals in preventive and rehabilitative fields better address these deficits.

According to Fitts' law, an individual's speed-accuracy tradeoff is only related to the object's properties. According to previous research, the movement time to hit the current target can be affected by the target of different size on the previous trial where the Fitts' law task is affected by trial history. However, in a dyadic context, the question is whether there is still a trial-to-trial transfer across individuals. In this study, Experiment 1 was conducted to investigate whether the current trial would be affected by the previous trial performed by the partner in a dyadic task. The results showed trial-to-trial transfer between individuals was affected by the difficulty of the action. The current movement was only affected by the previous difficult trial but not simple task. In order to investigate whether observing only novel targets would affect the current movement, we conducted Experiment 2, which showed that observing the target was not sufficient to generate effect transfer between trials. These findings suggest that the goal-directed movement can be affected by the observation of others. In addition, the effect of trial-to-trial transfer between individuals was influenced by task difficulty, which proved this effect was not a simple imitation.

Motor competence is associated with the perceived difficulty of a task. This study hypothesized that children with higher motor competence perceive certain tasks as less challenging than their peers with lower motor competence. As a result, children with higher motor competence were expected to set more ambitious goals for themselves while learning a new task compared to children with lower motor competence. To investigate the relationship between motor competence and the difficulty of self-set goals during motor learning, we included 48 children aged between eight and ten years, stratified into terciles; our analysis focused on 32 children from the highest and lowest terciles. The experimental task required participants to throw a 100 g bean bag toward a target located 3 meters away. Children were instructed to set goals before each block of 10 trials during the learning phase. Pretest, retention, and transfer tests were administered without imposed goals. Motor competence was assessed using the Motor Competence Assessment, which integrates scores from the task used to evaluate motor learning and the percentage increase in each block to assess the difficulty of the self-set goals. The findings revealed no significant correlation between motor competence and the difficulty of self-set goals. Nevertheless, higher motor competence was linked to enhanced performance during the acquisition phase, retention and transfer tests. These results suggest that although motor competence is associated with improved motor learning, it does not influence the level of challenge of the goals that children set for themselves.

The functional equivalence model suggests a common internal representation initiates both imagery and execution. This suggestion is supported by the mental chronometry effect, where there is a positive relation between task difficulty (as defined by the Index of Difficulty; ID) and imagined movement time. The present study extends this logic by examining whether imagery captures the spatial trajectory. Participants were initially tasked with the imagery and execution of a rapid aiming movement under different IDs. These initial attempts were adapted to configure auditory tones at early (25%) and late (75%) intervals for a separate set of imagery trials. If a tone had sounded, participants had to estimate post-trial where their imagined limb would have been located. The findings revealed increases in ID that coincided with increases in imagined and executed movement times. However, participant mean and standard deviation of estimated locations revealed limited differences between the early and late tones. Further inspection revealed some evidence for these estimated locations shifting further along in space following more rapid imagined movements. While equivalence is clearly evident within the temporal domain, there is comparatively little to suggest that this logic extends to the resolution required for simulating the spatial characteristics of movement.

To determine the influence of environmental complexity on cognitive-motor interaction during wheelchair propulsion. Fourteen participants completed two single- to dual-task trials of Serial-7 Subtraction Task and four environments varying in complexity. Differences in cognitive and motor function were determined through paired samples t-tests and percent changes (dual-task costs [DTCs]) were calculated. Within-subjects, repeated-measures ANOVAs were performed to determine differences in DTCs across environments. Cognitive function was maintained from the single- to dual-task trial in all environments (p ≥ 0.16) and yielded similar DTCs across environments (p = 0.80). Compromised motor function was observed in all environments (p ≤ 0.03) and yielded similar DTCs across environments (p ≥ 0.37). Wheelchair propulsion is attentionally demanding; however, environmental complexity did not exacerbate cognitive or motor dual-task costs.

Rapid lower limb coordination is directly related to physical activity skills in older adults and is controlled mainly by the central nervous system. This study aimed to investigate the association between chair stepping skills and neuromuscular properties in older adults. Fifty-eight community-dwelling older adults (72.0 ± 5.0 years) participated. High-density surface electromyography from the vastus lateralis (VL) was recorded and was decomposed into individual motor unit activities. The slope (MU slope) and intercept were calculated from the regression line between the individual motor unit recruitment thresholds and firing rates in each participant. Muscle thickness of the VL and vastus intermedius and echo intensity of the VL were evaluated using ultrasonography. While sitting on a chair, they repeatedly opened and closed their legs to position their feet outside and within 30-cm interval lines rapidly for 20 s. The mean steps were associated with echo intensity (r = 0.388, p < 0.01). Step variability was associated with the MU slope (r = 0.324, p = 0.03). These results suggest that the rapid lower-limb movement skills would be determined by neuromuscular quality, such as echo intensity and motor unit firing patterns, in older adults. The chair stepping test can be employed as a screening tool as an alternative to specific assessments.

This study examines the traces of movement trajectories for perception accuracy in expert performance, focusing on table tennis. Twenty participants (10 experts and 10 novices) performed self-generated movements for extended haptic accuracy tasks, and their performance was analyzed for absolute error and movement trajectory. The results reveal that the expert participants exhibited more movement entropy than novices, strategically sacrificing trajectory predictability to enhance haptic perception accuracy. These findings reveal the adaptive strategies used by experts to optimize performance and provide insights into the balance between movement entropy and perception accuracy in skilled motor control.