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Acting in the environment results in both intended and unintended consequences. Action consequences provide feedback about the adequacy of actions while they are in progress and when they are completed and therefore contribute to monitoring actions, facilitate error detection, and are crucial for motor learning. In action imagery, no actual action takes place, and consequently, no actual action consequences are produced. However, imagined action consequences may replace actual action consequences, serving a similar function and facilitating performance improvements akin to that occurring with actual actions. In this paper, we conceptualize action imagery as a simulation based on internal models. During that simulation, forward models predict action consequences. A comparison of predicted and intended action consequences sometimes indicates the occurrence of action errors (or deviations from optimal performance) in action imagery. We review research indicating that action errors are indeed sometimes imagined in action imagery. These results are compatible with the view that action imagery is based on motor simulation but incompatible with the view that action imagery is solely based on abstract knowledge. The outlined framework seems suitable to cover a wide range of action imagery phenomena and can explain action imagery practice effects.

Theories of motor imagery conflict in their account of what happens during an imagined movement, with some suggesting that movement is simulated while others suggest it involves creating and elaborating upon an internal representation of the movement. Here we report evidence that imagery involves the simulation of a movement and that it varies in accuracy. Two groups of participants performed a motor task focused on challenging movement execution either overtly or via motor imagery. Overt performance was used to model expected performance given required movement characteristics (i.e., speed, complexity, familiarity), which was then compared with self-reported accuracy during imagery. Movement characteristics had a large effect on self-reported accuracy compared with a small effect of imagery vividness. Self-reported accuracy improved across trials with familiar movements compared with novel movements in a similar manner for each group. The complexity of the imagined movement did not influence movement time during imagery or overt trials, further suggesting that imagined movements are simulated rather than abstractly represented. Our results therefore support models of motor imagery that involve the simulation of a movement and its viability, which may be the basis of imagery-based motor learning. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Sensory feedback has traditionally been considered critical for motor learning. While it has been shown that motor learning can occur in the absence of visual or somatosensory feedback, it is thought that at least one must be present. This assumption contrasts with literature demonstrating that motor imagery (MI) - the mental rehearsal of a movement - is capable of driving motor learning even though the lack of actual execution precludes sensory feedback related to movement. However, studies of MI typically employ simple tasks that do not require improvements in motor execution per se, suggesting that MI might improve task performance primarily through perceptual mechanisms. To avoid this limitation, we designed a novel motor task requiring the repeated execution of unfamiliar kinematic trajectories where learning was assessed through changes in the speed-accuracy function (SAF) across five sessions. General task performance was controlled for by assessing performance on randomly generated trajectories. Groups included physical practice (PP; with and without added visual feedback), MI, and perceptual control (PC), the latter of which only observed the trajectories. All groups performed physically on the final session. Upon the final session, the MI group performed better than the PC group, and better than initial session PP performance. These results suggest that motor learning occurred in the MI group despite the lack of sensory feedback related to the movement, and that this learning was not simply the result of perceptual learning. Our results question long-standing assumptions about MI based learning and the necessity of feedback in motor learning generally.

This study’s purpose is to characterize the performance of a prototype functional near-infrared spectroscopy (fNIRS) headband meant to enable quick and easy measurements from the sensorimotor cortices. The fact that fNIRS is well-suited to ergonomic designs (i.e., their ability to be made wireless, their relative robustness to movement artifacts among other characteristics) has resulted in many recent examples of novel ergonomic fNIRS systems; however, the optical nature of fNIRS measurement presents an inherent challenge to measurement at areas of the brain underlying haired parts of the head. It is for this reason that the majority of ergonomic fNIRS systems that have been developed to date target the prefrontal cortex. In the present study we compared the performance of a novel, portable fNIRS headband compared with a stationary full headcap fNIRS system to measure sensorimotor activity during simple upper- and lower-extremity tasks, in healthy individuals >50 years of age. Both fNIRS systems demonstrated the expected pattern of hemodynamic activity in both upper- and lower-extremity tasks, and a comparison of the contrast-to-noise ratio between the two systems suggests the prototype fNIRS headband is non-inferior to a full head cap fNIRS system regarding the ability to detect a physiological response at the sensorimotor cortex during these tasks. These results suggest the use of a wireless and fibreless fNIRS design is feasible for measurement at the sensorimotor cortex.

OCCUPATIONAL APPLICATIONS Better understanding of lower limb muscle activations and habituation processes has implications for injury prevention. This study examined the influence of repeated expos...

Motor imagery (MI), the mental rehearsal of movement, facilitates learning by driving brain activation similar to that of physical practice (PP). However, a growing body of evidence suggests that learning via MI relies more on effector independent as opposed to effector dependent encoding. One approach to probing the nature of MI based learning is to study the primary motor cortex (MC), a brain region known to be critical to effector dependent encoding, but whose involvement in MI is debatable. The current study sought to inform on the nature of MI-based learning by examining the extent to which participants could learn via MI following inhibition of the MC using repetitive transcranial magnetic stimulation (TMS). Forty-seven participants completed an MI-based implicit sequence learning paradigm after receiving inhibitory TMS to the contralateral or ipsilateral MC (TMS groups), or with the coil angled away from the scalp (Sham). The extent to which participants learned was assessed via reaction time differences (dRT) and effect sizes between repeated and random sequences. Similar dRT values and moderate effect sizes were observed across all groups, providing evidence that inhibition of the MC did not disrupt MI-based learning. As the MC is critical to effector dependent encoding, the current findings suggest that MI-based learning does not rely on effector dependent encoding and unlike PP, is more effector independent in nature. Ultimately, these results inform on the nature of MI-based learning.

Purpose: Evidence has suggested that patients' expectations influence the clinical course when they present with low back pain (LBP). However, little empirical evidence has outlined the nature of these expectations. The aim of this study was to describe LBP patients' expectations of physiotherapy. Method: Seventy-nine adult patients who had LBP for more than 16 weeks and were referred for physiotherapy at two hospital physiotherapy departments in St. John's, Newfoundland and Labrador, were included. They filled out a questionnaire detailing their expectations of treatment. Results: Before treatment, more than 90% of patients expected a physical examination, tests or investigations, a diagnosis, reassurance and advice, and clear explanations of causation, symptom management, and benefits and risks of treatment. Approximately half hoped for a prescription or referral to a specialist, and about 60% hoped to discuss problems in their life. Conclusions: The findings of this study indicate that patients attend physiotherapy with clear expectations about what information should be provided. Most expected tests or investigations leading to diagnosis and an explanation of causation; this presents a challenge for clinicians, given the current understanding of LBP reflected in international practice guidelines. The fact that more than half of the patients wanted to discuss problems in their life points to the need for physiotherapists to consider LBP from a bio-psychosocial perspective.

Motion simulation platforms are often used to study the effects of moving environments on the postural stability of maritime workers. During motion simulation studies, the effects of previous experience are not often considered when recruiting control participants. Previous experience in motion simulation studies may violate assumptions of novice participants, and previous experiences in activities that regularly challenge balance may also influence performance. Thus, the purpose of this study was to investigate the effects of previous participation in motion simulation studies or previous skill training (specifically dance) on postural stability and lower limb neuromuscular activity in a simulated ocean environment. Thirty-seven participants were recruited; 12 participants with previous motion bed experience, 13 dancers, and 12 control participants. Results indicated that both motion bed experience and dance training had significantly better postural stability performance and decreased lower limb...

Motor imagery (MI), the mental rehearsal of movement, is an effective means for acquiring a novel skill, even in the absence of physical practice (PP). The nature of this learning, be it perceptual, motor, or both, is not well understood. Understanding the mechanisms underlying MI-based skill acquisition has implications for its use in numerous disciplines, including informing best practices regarding its use. Here we used an implicit sequence learning (ISL) task to probe whether MI-based skill acquisition can be attributed to perceptual or motor learning. Participants (n = 60) randomized to 4 groups were trained through MI or PP, and were then tested in either perceptual (altering the sensory cue) or motor (switching the hand) transfer conditions. Control participants (n = 42) that did not perform a transfer condition were utilized from previous work. Learning was quantified through effect sizes for reaction time (RT) differences between implicit and random sequences. Generally, PP-based training led to lower RTs compared with MI-based training for implicit and random sequences. All groups demonstrated learning (p < .05), the magnitude of which was reduced by transfer conditions relative to controls. For MI-based training perceptual transfer disrupted performance more than for PP. Motor transfer disrupted performance equally for MI- and PP-based training. Our results suggest that MI-based training relies on both perceptual and motor learning, while PP-based training relies more on motor processes. These results reveal details regarding the mechanisms underlying MI, and inform its use as a modality for skill acquisition. (PsycINFO Database Record

INTRODUCTION The potential relationship between bilateral quadriceps inhibition in individuals with unilateral anterior knee pain (AKP) and gamma loop dysfunction is examined in this study. METHODS Twelve individuals with unilateral AKP and 10 healthy controls were recruited. Quadriceps voluntary activation (%VA) was quantified using a triggered interpolated twitch technique. Gamma loop function was assessed through knee extension maximum voluntary isometric contractions before and after 20 minutes of 50-Hz patellar tendon vibration. RESULTS The AKP group exhibited 5.7% lower %VA bilaterally compared with controls (P = 0.039, Cohen d = 0.79). After prolonged vibration, both groups exhibited an average 8.5% reduction in knee extension force in each limb (P

Central or postural set theory suggests that the central nervous system uses short term, trial to trial adaptation associated with repeated exposure to a perturbation in order to improve postural responses and stability. It is not known if longer-term prior experiences requiring challenging balance control carryover as long-term adaptations that influence ability to react in response to novel stimuli. The purpose of this study was to determine if individuals who had long-term exposure to balance instability, such as those who train on specific skills that demand balance control, will have improved ability to adapt to complex continuous multidirectional perturbations. Healthy adults from three groups: 1) experienced maritime workers (n = 14), 2) novice individuals with no experience working in maritime environments (n = 12) and 3) individuals with training in dance (n = 13) participated in the study. All participants performed a stationary standing task while being exposed to five 6 degree of freedom motions designed to mimic the motions of a ship at sea. The balance reactions (change-in-support (CS) event occurrences and characteristics) were compared between groups. Results indicate dancers demonstrated significantly fewer CS events than novices during the first trial, but did not perform as well as those with offshore experience. Linear trend analyses revealed that short-term adaptation across all five trials was dependent on the nature of participant experience, with dancers achieving postural stability earlier than novices, but later than those with offshore experience. These results suggest that long term previous experiences also have a significant influence on the neural control of posture and balance in the development of compensatory responses.