Journal of Motor Behavior最新文献

Postural control involves complex nonlinear dynamics influenced by the interaction and adaptation of different sensory inputs. However, it is not how these inputs interact with one another due to the complex complications associated with aging, particularly concerning the nonlinear dynamics of postural sway. This study aimed to examine how different sensory inputs, surface conditions, and aging factors to influence postural control mechanisms between young and older by investigating the nonlinear dynamics of postural control using the stabilogram diffusion analysis (SDA) and entropy methods. SDA parameters were much greater on foam surfaces than on firm surfaces for both groups in eyes-open and eyes-closed conditions (p ≤ 0.05). For older subjects, there were significant differences in entropy values between firm and foam surfaces (p ≤ 0.05) but no significant difference between eyes conditions (p > 0.05). For both SDA and entropy parameters, surface and age interaction potentially revealed significant differences between young and older subjects (p ≤ 0.05) than eyes and age interaction. The present study provided insight into uncovering the complex relationships between sensory inputs, surface conditions, age, and their potential interaction effects on postural control mechanisms that could mitigate falls and alleviate the fear of falling, particularly in older populations.

Lower back disorders (LBDs) affect a large proportion of the population, and treatment for LBDs have been shifting toward individualized, patient-centered approaches. LBDs are typically associated with poor proprioception. Therefore, there has been a recent uptake in the utilization of wearable sensors that can administer biofeedback in various industrial, clinical, and performance-based settings to improve lumbar proprioception. The aim of this study was to investigate whether wearable sensor-derived acute auditory biofeedback can be used to improve measures of gross lumbar proprioception. To assess this, healthy participants completed an active target repositioning protocol, followed by a training period where lumbar-spine posture referenced auditory feedback was provided for select targets. Target re-matching abilities were captured before and after acute auditory biofeedback training to extract measures related to accuracy and precision across spine flexion targets (i.e., 20%, 40%, 60%, 80% maximum). Results suggest a heterogenous response to proprioceptive training whereby certain individuals and spine flexion targets experienced positive effects (i.e., improved accuracy and precision). Specifically, results suggest that mid-range flexion targets (i.e., 40-60% maximum flexion) benefited most from the acute auditory feedback training. Further, individuals with poorer repositioning abilities in the pre-training assessment showed the greatest improvements from the auditory feedback training.

Dyad practice has proven to be an efficient, and in some cases, a more effective method of promoting motor learning compared to individual practice. Further, providing individuals control over their own or another learner's practice environment has also been shown to be superior for skill learning relative to individuals without control. The purpose of the experiment was to assess learner-controlled role-switching in dyad practice conditions. In dyads, partners either alternated actor and observer roles on a trial-to-trial basis, or under novel learner-controlled conditions wherein either the actor or the observer was given control over when the partners should switch roles. Participants practiced a speed cup-stacking task and learning was assessed in 24-h retention and transfer tests. Although there were no learning differences between dyad conditions, paired learners effectively chose when to switch roles with their partner, without undermining learning. The results also highlight the dynamic nature of dyad practice as the observers chose to switch roles more frequently than the actors, yet both dyad groups adopted comparable switching strategies by alternating roles following relatively 'good' and 'bad' trials. This experiment provides further support for dyad practice as an efficient and effective method of skill learning.

Virtual reality has gained more attention in the physical training field, but few studies focus on the effects of VR on older adults. Based on existing study we suggest that VR-based upper limb training might be more effective for older adults and used functional near inferred spectrum and movement analysis to evaluate the effects of VR-based training on older adults. 20 older and 20 youth adults were recruited to perform VR training by extending their upper limb to reaching the objects, and non-VR training as a contrast. Both age-related and task-related differences were found in cortical activation, showing that the VR training has aroused more cortical activation. The older groups have more intensive movement but perform worse in terms of task completion. Both groups performed better in VR, and the difference in the older group was higher.

Structural learning is characterized by facilitated adaptation following training on a set of sensory perturbations all belonging to the same structure (e.g., 'visuomotor rotations'). This generalization of learning is a core feature of the motor system and is often studied in the context of interlimb transfer. However, such transfer has only been demonstrated when participants learn to counter a specific perturbation in the sensory feedback of their movements; we determined whether structural learning in one limb generalized to the contralateral limb. We trained 13 participants to counter random visual feedback rotations between +/-90 degrees with the right hand and subsequently tested the left hand on a fixed rotation. The structural training group showed faster adaptation in the left hand in both feedforward and feedback components of reaching compared to 13 participants who trained with veridical reaching, with lower initial reaching error, and straighter, faster, and smoother movements than in the control group. The transfer was ephemeral - benefits were confined to roughly the first 20 trials. The results demonstrate that the motor system can extract invariant properties of seemingly random environments in one limb, and that this information can be accessed by the contralateral limb.

Postural control is influenced by cognition. In most studies, variability of motor output has been considered regardless of variability in patterns of joint coordination. Uncontrolled manifold framework has been applied to decompose the joint's variance in two components. The first component leaves position of the center of mass in anterior-posterior direction (CoM_AP) unchanged (V_UCM) while the second component is in charge of variations of CoM (V_ORT). In this study, 30 healthy young volunteers were recruited. The experimental protocol consisted of three random conditions: quiet standing on a narrow wooden block without a cognitive task (NB), quiet standing on a narrow wooden block with an easy cognitive task (NBE), and quiet standing on a narrow wooden block with a difficult cognitive task (NBD). Results showed that CoM_AP sway in NB condition was higher than both NBE and NBD conditions (p = .001). V_ORT in NB condition was higher than NBE and NBD conditions (p = .003). V_ORT in NB condition was higher than NBE and NBD conditions (p = .003). V_UCM was unchanged in all conditions (p = 1.00) and synergy index in NB condition was smaller than NBE and NBD conditions (p = .006). These results showed that postural synergies increased under dual-task conditions.

Previous studies showed numerous evidence for the interlimb asymmetries in motor performance during arm reaching movements. Furthermore, these interlimb asymmetries have been shown to associate with spatial patterns of hand selection behavior. Importantly, these interlimb asymmetries can be modified systematically by occlusion of visual feedback, or a long-term sports training. In this study, we asked about the effects of a short-term training on interlimb asymmetries. Eighteen healthy young participants underwent a 12-week novice traditional archery training (TAT). Their unimanual dominant and nondominant arm reaching movement performance was assessed before and after TAT. We found that movement accuracy, movement precision, and movement efficiency in the experimental group have all improved significantly as a result of TAT. These improvements were comparable across both arms, thus the interlimb differences in movement performance were not affected by the short-term TAT and remained similar. These results suggest that while short-term training may contribute positively to reaching performance, it is unlikely to have a significant impact on the differences observed between the dominant and nondominant arms. This unique characteristics of dominant and nondominant arm should be taken into consideration when developing targeted sports and rehabilitation programs for athletes or individuals with acute or chronic motor deficits.

Increased physical activity, such as walking, is often prescribed to address obesity. Several factors that may influence the connection between obesity and walking include the biomechanics of gait, pain, depressive symptoms, physical health, and activity. The objective of this study was to assess the moderation and mediation effects of knee pain and buckling, depressive symptoms, physical activity, and physical health on spatiotemporal gait parameters in individuals with obesity. Forty participants with obesity performed a task in which they walked on flat ground and crossed an obstacle. Measures of knee pain and buckling, depressive symptoms, physical activity, and physical health were collected. We conducted mediation analyses with knee buckling and pain as mediators of the effect of the BMI on spatiotemporal gait parameters. Moderation analyses were performed with depressive symptoms, physical activity, and physical health as moderators of the effect of BMI on spatiotemporal gait parameters. We found that depressive symptoms and physical health moderated the relationship between BMI and Step Width in people with obesity. These effects were pronounced when participants crossed an obstacle. In conclusion, depressed mood and physical health influence the relationship between obesity and walking. These factors present potential avenues for rehabilitation interventions to aid individuals with obesity.

Newly acquired motor skills can be critically driven by different rest periods during practice. Specifically, in the initial stages of motor skill acquisition, the interval between individual trials plays a pivotal role in facilitating effective motor performance, such as in the case of throwing. The objective of this research was to determine the optimal inter-trial rest period promoting efficient motor performance, focusing on two specific motor task actions. In a randomized counterbalanced cross-over research design 169 high-school students aged 14 were studied (M = 150; F = 19). In one block, participants performed 10 basketball free throws with a short rest interval (< 5 s) and 10 other throws with a long rest interval (∼50-60 s). In a second block, they threw a regular size tennis ball into a 1-m diameter circle on the floor at 6.75 m, again throwing 10 times with a short inter-trial rest interval and 10 times with a long inter-trial rest interval. The order of the rest intervals within each block was randomized and counterbalanced. With a repeated measures two-way analysis of variance, greater accuracy seemed to be associated with short intra-set rest intervals as there were significant main effects of both conditions (F_1,167 = 368.0, p < 0.001, η²_p = 0.271) and resting time (F_1,167 = 18.6, p < 0.001, η²_p = 0.192) and no significant interaction "condition by time". Fast practice was efficient independently of the complexity of the throwing task, suggesting robust support for schema theory.

Motor behaviour using upper-extremity prostheses of different levels is greatly variable, leading to challenges interpreting ideal rehabilitation strategies. Elucidating the underlying neural control mechanisms driving variability benefits our understanding of adaptation after limb loss. In this follow-up study, non-amputated participants completed simple and complex reach-to-grasp motor tasks using a body-powered transradial or partial-hand prosthesis simulator. We hypothesised that under complex task constraints, individuals employing variable grasp postures will show greater sensorimotor beta activation compared to individuals relying on uniform grasping, and activation will occur later in variable compared to uniform graspers. In the simple task, partial-hand variable and transradial users showed increased neural activation from the early to late phase of the reach, predominantly in the hemisphere ipsilateral to device use. In the complex task, only partial-hand variable graspers showed a significant increase in neural activation of the sensorimotor cortex from the early to the late phase of the reach. These results suggest that grasp variability may be a crucial component in the mechanism of neural adaptation to prosthesis use, and may be mediated by device level and task complexity, with implications for rehabilitation after amputation.