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Motor imagery (MI) is the capacity to mentally perform one or a set of movements without concomitant overt action. MI training has been show to enhance the subsequent motor performance. While the benefits of MI to manage stress have been extensively documented, the reverse impact of stress on MI received far less attention. The present study thus aimed to evaluate whether acute stress might influence MI abilities. Thirty participants were assigned either to a stress or a control group. The Socially Evaluated Cold Pressor Test (SECPT) was used to induce stress, with heart rate, electrodermal activity, salivary cortisol, and self-report perceived levels of stress being monitored during the experiment. Stress induction was followed by both implicit (laterality judgment) and explicit (sequential pointing) MI tasks. Main results showed a deleterious impact of stress on implicit MI, while explicit MI was not altered. These exploratory findings provide a deeper understanding of stress effects on cognition, and practically support that under stressful conditions, as during a sport competition or rehabilitation contexts, explicit MI should be prioritized.

Limb disuse causes overt, measurable alterations in motor functions. Motor imagery (MI) practice has been used as a behavioral strategy to prevent motor impairments due to limb disuse or immobilization. Yet, how MI operates at the neural level in the context of short-term limb immobilization remains understudied. We hypothesized that MI treatment applied during 12 h of arm immobilization prevents immobilization-related changes in resting-state electroencephalographic (rsEEG) power and functional connectivity. Fourteen participants first underwent rsEEG after 12 h of normal motor activity (without immobilization). Then, rsEEG recording was performed after 12 h of arm immobilization either with MI treatment or without, each condition separated by 1 week, according to a randomized within-subjects design. MI treatment consisted in performing varied visual and kinaesthetic MI exercises (5 sessions of 15 min every two hours). The results showed that in the delta, theta, alpha and beta frequency bands, interhemispheric difference in sensors power over the motor cortex (i.e. C3 vs. C4) was reduced after arm immobilization, while it did not change when MI treatment was delivered during the immobilization period. Moreover, functional connectivity across the sensors-network in the delta (1-4 Hz) and alpha (8-12 Hz) frequency bands decreased after immobilization while it was restored by MI treatment. To conclude, MI counteracts functional neural changes within and between motor regions in the context of limb immobilization. Practical applications for motor rehabilitation strategies, particularly in stroke patients, are also discussed.

Motor imagery (MI) is usually facilitated when performed in a congruent body position to the imagined movement, as well as after actual execution (AE). A lower-limb amputation (LLA) results in important structural and functional changes in the sensorimotor system, which can alter MI. In this study, we investigated the effects of body position and AE on the temporal characteristics of MI in people with LLA. Ten participants with LLA (mean age = 59.6 ± 13.9 years, four females) and ten gender- and age-matched healthy control participants (mean age = 60.1 ± 15.4 years, four females) were included. They performed two locomotor-related tasks (a walking task and the Timed Up and Go task) while MI times were measured in different conditions (in congruent/incongruent positions and before/after AE). We showed that MI times were significantly shorter when participants imagined walking in a congruent-standing position compared to an incongruent-sitting position, and when performing MI after actual walking compared to before, in both groups. Shorter MI times in the congruent position and after AE suggest an improvement of MI’s temporal accuracy (i.e. the ability to match AE time during MI) in healthy individuals but not in the LLA group.

The present double-blinded, randomized controlled study sought to compare the effects of a full-body manual massage (MM) and a foam rolling (FR) intervention on subjective and objective indexes of performance and well-being. A total of 65 healthy individuals were randomly allocated to an FR, MM, or a control group who received a cognitively oriented relaxation routine. Self-report ratings of perceived anxiety, muscle relaxation, and muscle pain were used to index changes in affect and physical sensations. The sit-and-reach and toe-touch tests, as well as a mental calculation task, were used to index motor and cognitive performances, respectively. We also conducted resting-state electroencephalography and continuous skin conductance recordings before and after the experimental intervention. Both FR and MM groups exhibited neural synchronization of alpha and beta oscillations during the posttest. Skin conductance increased from the pretest to the posttest in the relaxation group, but decreased in the FR group. All interventions improved range of motion, although only the MM group outperformed the relaxation group for the toe-touch performance. MM was associated with reduced muscle pain and increased muscle relaxation. Reduced perceived anxiety after the intervention was observed in the FR group only. Overall, MM and FR both improved objective and subjective indexes of performance and well-being. Differences between the two massage interventions are discussed in relation to the effects of pressure stimulation on autonomic regulations and the proactive vs. retroactive nature of FR, compared to MM.

Background Self-myofascial release is an emerging technique in strength and conditioning. Yet, there is no consensus regarding optimal practice guidelines. Here, we investigated the acute effects of various foam rolling interventions targeting quadriceps muscles, with or without sliding pressures. Methods We conducted a blinded randomized control pilot trial in 42 healthy weightlifting athletes over 4 weeks. Participants were randomly allocated to one of the four intervention (120 s massage routine) groups: foam rolling, roller massager, foam rolling with axial sliding pressures, foam rolling with transverse sliding pressures. Knee range of motion, skin temperature and subjective scores of the perceived heat, range of motion, muscle pain and relaxation were the dependent variables. Measurements were carried on before, after and up to 15 min (follow-up) after the massage intervention. Results The range of motion increased immediately after the various foam rolling interventions (+ 10.72%, 95% CI 9.51 to 11.95, p p p Conclusions Subjective indexes of heat, range of motion, muscle pain and relaxation improved immediately after the intervention, but also gradually returned to the pre-intervention baseline. Overall, combining foam rolling with sliding pressures did not yield additional benefits from objective measures.

BACKGROUND There is now ample evidence that motor imagery contributes to enhance motor learning and promote motor recovery in patients with motor disorders. Whether motor imagery practice is likely to facilitate mobility in patients suffering from knee osteoarthritis, at 6-months after total knee arthroplasty, remains unknown. AIM This trial was designed to evaluate the therapeutic effectiveness of implementing motor imagery into the classical course of physical therapy at 6-months after total knee arthroplasty. DESIGN Randomized controlled trial. POPULATION Twenty-four patients with unilateral total knee arthroplasty were assigned to a motor imagery or control group in a test-retest procedure, following a rehabilitation program as outpatients. METHODS During both the pre- and post-test, a set of strength and functional mobility measures were assessed: quadriceps strength, peak knee flexion during the swing phase, performance at the timed up and go test, stair climbing test, and 6-minute walk test, and finally Oxford knee score. In addition to a common physical therapy program, the motor imagery group practiced additional motor imagery exercises, while participants of the control group were subjected to a period of neutral activities for an equivalent amount of time. RESULTS Data provided evidence that motor imagery enhanced the quadriceps muscle strength of the operated knee (F (1, 22)=10.36, P=0.003), improved the peak knee flexion during the swing phase (F (1, 22)=31.52, P

Background Amputation of a lower-limb results in a severe decrease of functional mobility that deeply alters independent living. Motor imagery (MI) refers to the mental representation of an action without engaging its actual execution. The repetitive use of MI has been shown to contribute to promote motor recovery and phantom-limb pain alleviation. Aim Given the importance of invoking accurate images to benefit from MI practice, and considering the link between motor capacities and MI, the present study investigated the effect of a rehabilitation program on MI ability in patients with lower-limb amputation. Design Observational and longitudinal study. Setting Patients recruited from the Amputation program at the Institut de Readaptation en Deficience Physique de Quebec (IRDPQ), in Quebec City, Canada. Population Patients with trans-tibial or transfemoral amputation, following a rehabilitation program as outpatients. Methods MI ability of the patients was measured at three different time points along the course of physical therapy. Results The data revealed a positive effect of the rehabilitation program on MI accuracy of locomotor tasks, and greater MI vividness and accuracy for single-joint movements that patients were still able to physically perform. Conclusions These findings suggest that MI abilities and actual motor performance are mirrored in a congruent fashion. Clinical rehabilitation impact Therapists should consider this critical aspect when including MI practice in rehabilitation programs among patients with lower-limb amputation.

Action observation (AO) alone or combined with motor imagery (AO + MI) has been shown to engage the motor system. While recent findings support the potential relevance of both techniques to enhance muscle function, this issue has received limited scientific scrutiny. In the present study, we implemented a counterbalanced conditions design where 21 participants performed 10 maximal isometric contractions (12-s duration) of elbow flexor muscles against a force platform. During the inter-trial rest periods, participants completed i) AO of the same task performed by an expert athlete, ii) AO + MI, i.e. observation of an expert athlete while concurrently imagining oneself performing the same task, and iii) watching passively a video documentary about basketball shooting (Control). During force trials, we recorded the total force and integrated electromyograms from the biceps brachii and anterior deltoideus. We also measured skin conductance from two finger electrodes as an index of sympathetic nervous system activity. Both AO and AO + MI outperformed the Control condition in terms of total force (2.79–3.68%, p

We aimed at studying the effect of Motor Imagery (MI), i.e., the mental representation of a movement without executing it, on breath-holding performance. Classical guidelines for efficient MI interventions advocate for a congruent MI practice with regards to the requirements of the physical performance, specifically in terms of physiological arousal. We specifically aimed at studying whether an incongruent form of MI practice might enhance the breath-hold performance. In a counterbalanced design including three experimental sessions, participants engaged in maximal breath-hold trials while concomitantly performing i) MI of breathing, ii) MI of breath-hold, and iii) an "ecological" breath-hold trial, i.e., without specific instructions of MI practice. In addition to breath-hold durations, we measured the cardiac activity and blood oxygen saturation. Performance was improved during MI of breathing (73.06 s ± 24.53) compared to both MI of breath-hold (70.57 s ± 18.15) and the control condition (67.67 s ± 19.27) (p 0.05). The mechanisms underlying breath-hold performance improvements during MI of breathing remain uncertain. MI of breathing might participate to decrease the threat perception associated with breath-holding, presumably due to psychological and physiological effects associated with the internal simulation of a breathing body state.

Mini-invasive surgery—for example, laparoscopy—has challenged surgeons’ skills by extending their usual haptic space and displaying indirect visual feedback through a screen. This may require new mental abilities, including spatial orientation and mental representation. This study aimed to test the effect of cognitive training based on motor imagery (MI) and action observation (AO) on surgical skills. A total of 28 postgraduate residents in surgery took part in our study and were randomly distributed into 1 of the 3 following groups: (1) the basic surgical skill, which is a short 2-day laparoscopic course + MI + AO group; (2) the basic surgical skill group; and (3) the control group. The MI + AO group underwent additional cognitive training, whereas the basic surgical skill group performed neutral activity during the same time. The laparoscopic suturing and knot tying performance as well as spatial ability and mental workload were assessed before and after the training period. We did not observe an effect of cognitive training on the laparoscopic performance. However, the basic surgical skill group significantly improved spatial orientation performance and rated lower mental workload, whereas the 2 others exhibited lower performance in a mental rotation test. Thus, actual and cognitive training pooled together during a short training period elicited too high a strain, thus limiting potential improvements. Because MI and AO already showed positive outcomes on surgical skills, this issue may, thus, be mitigated according to our specific learning conditions. Distributed learning may possibly better divide and share the strain associated with new surgical skills learning.

International audience; During bimanual coordination, that is, manipulating with the dominant hand an object held by the postural hand, anticipatory postural adjustments are required to cancel the perturbations and ensure postural stabilization. Using magnetoencephalography (MEG), we investigated changes mediating the acquisition of anticipatory postural adjustments during a bimanual load-lifting task. Participants lifted a load with their right hand, hence triggering the fall of a second load fixed to their left (postural) forearm. During ACQUISITION, the onset of load-lifting and the fall of the second load were experimentally delayed after few trials. During CONTROL, load-lifting triggered the fall of the second load without delay. Upward elbow rotation decreased with trial repetition during ACQUISITION, hence attesting the ongoing acquisition of anticipatory postural adjustments. Bilateral event-related desynchronisation (ERD) of the alpha rhythm (8-12 Hz) was recorded. Generators of the mu rhythm were found within central and associative motor regions. Their spatial distribution within the hemisphere contralateral to the load-lifting arm was less refined and circumscribed during ACQUISITION compared to CONTROL. Regression analyses emphasized the specific involvement of the precuneus in the right hemisphere contralateral to the postural forearm, and a medial prefrontal region in the left hemisphere. Analyses of the time course power showed that an increase in preunloading activation within the precuneus and a decrease in postunloading inhibition within the medial prefrontal region were associated with the acquisition of anticipatory postural adjustments. The study provides original insights into cortical activations mediating the progressive tuning of anticipatory postural adjustments during the acquisition stage of motor learning.

Motor imagery contributes to enhance the (re)learning of motor skills through remapping of cortical networks. Combining motor imagery with anodal transcranial direct-current stimulation (a-tDCS) over the primary motor cortex has further been shown to promote its beneficial effects on postural control. Whether motor imagery should be performed concomitantly to a-tDCS (over depolarized membrane) or consecutively (over changing neurotransmitters activity) remains to be elucidated. In the present study, we measured the performance in a postural control task before and after three experimental conditions. Participants received a-tDCS before (tDCSBefore), during (tDCSDuring), or both before and during motor imagery training (tDCSBefore + During). Performance was improved after tDCSDuring, but not after both the tDCSBefore and tDCSBefore + During conditions. These results support that homeostatic plasticity is likely to operate following a-tDCS through decreasing cortical excitability and that motor imagery should be performed during anodal stimulation for optimum gains.

International audience; The efficacy of motor imagery (MI) practice to facilitate muscle stretching remains controversial and the underlying neurophysiological mechanisms unexplored. We evaluated the effects of MI practice during a sit-and reach task. Healthy participants were randomly assigned to a MI practice (n = 15) or Control (n = 15) group and completed 2 blocks of 5 sit-and-reach trials. During the first block (B1), participants performed 5 maximal stretching trials of 10s. During the second block (B2), trials were divided into two consecutive parts: i) reproducing the maximum performance of B1 (10s, B2 part 1), and ii) attempting to outperform the maximum performance of B1 (10s, B2 part 2). Participants performed kinesthetic MI of hamstring stretching during B2 trials in the MI practice group. We recorded electromyography from the hamstring and rectos femoris of the dominant leg. We also processed skin conductance as an index of sympathetic activity. We measured greater performance improvements from B1 to B2 part 2 in the MI practice group compared to Control (p < 0.05). Participants in the MI practice group exhibited reduced hamstring activation during both B2 part 1 (p < 0.001) and B2 part 2 (p < 0.001) compared to Control. Skin conductance revealed higher sympathetic activation during B2 part 2 compared to both B1 and B2 part 1 in the two groups. Thus, performing MI during actual movement is likely to improve stretching performance through reduced muscle activation. Such improvement may be grounded in a cortical gain over spinal reflexes.

International audience; Motor imagery (MI, the mental representation of an action without engaging in its actual execution) is a therapeutically relevant technique to promote motor recovery after neurologic disorders. MI shares common neural and psychological bases with physical practice. Interestingly, both acute and progressive neurologic disorders impact brain motor networks , hence potentially eliciting changes in MI capacities. How experimental neuroscientists and medical practitioners should assess and take into account these changes in order to design fruitful interventions is largely unresolved. Understanding how the psychometric, behavioral and neuro-physiological correlates of MI are impacted by neurologic disorders is required. To address this brain-behavior issue, we conducted a systematic review of MI data in stroke, Parkinson's disease, spinal cord injury, and amputee participants. MI evaluation methods are presented. Redundant MI profiles, primarily based on psychometric and behavioral evaluations, emerged in each clinical population. When present , changes in the psychometric and behavioral correlates of MI were highly congruent with the corresponding motor impairments. Neurophysiological recordings yielded specific changes in cerebral activations during MI, which mirrored structural and functional reorganizations due to neuroplasticity. In this view, MI capacities may not be deteriorated per se by neurologic diseases resulting in chronic motor incapacities, but adjusted to the current state of the motor system. Literature-driven orientations for future clinical research are provided.

The neurophysiological substrates underlying motor imagery are now well established. However, the neural processes of motor inhibition while mentally rehearsing an action are poorly understood. This concern has received limited experimental investigations leading to divergent conclusions. Whether motor command suppression is mediated by specific brain structures or by intracortical facilitation/inhibition is a matter of debate. Interestingly, although motor commands are inhibited during motor imagery (MI) in healthy participants, spinal cord injury may result in weakened motor inhibition. Using magentoencephalography, we observed that mental and actual execution of a goal-directed pointing task elicited similar primary motor cortex activation in a C6-C7 quadriplegic patient, thus confirming the hypothesis of weakened motor inhibition during MI. In an age-matched healthy control participant, however, primary motor area activation during MI was significantly reduced compared to physical practice. Brain activation during actual movement resulted in enhanced recruitment of premotor areas in the patient. In the healthy participant, we found functional relationships between the primary motor area and peri-rolandic sites including the primary sensory area and the supplementary motor area during MI. This neural network was not activated when the quadriplegic patient performed MI. We assume that the primary sensory area and the supplementary motor area may be part of a functional network underlying motor inhibition during MI. These data provide insights into brain function changes due to neuroplasticity after spinal cord injury and evidence cortical substrates underlying weakened motor inhibition during MI after deafferentation and deefferentation.

There is now compelling evidence that motor imagery (MI) promotes motor learning. While MI has been shown to influence the early stages of the learning process, recent data revealed that sleep also contributes to the consolidation of the memory trace. How such “online” and “offline” processes take place and how they interact to impact the neural underpinnings of movements has received little attention. The aim of the present review is twofold: i) providing an overview of recent applied and fundamental studies investigating the effects of MI practice on motor learning, and ii) detangling applied and fundamental findings in support of a sleep contribution to motor consolidation after MI practice. We conclude with an integrative approach of online and offline learning resulting from intense MI practice in healthy participants, and underline research avenues in the motor learning/clinical domains.

There is compelling evidence that motor imagery contributes to improved motor performance, and recent work showed that dynamic motor imagery (dMI) might provide additional benefits by comparison with traditional MI practice. However, the efficacy of motor imagery in different states of physical fatigue remains largely unknown, especially as imagery accuracy may be hampered by the physical fatigue states elicited by training. We investigated the effect of static motor imagery (sMI) and dMI on free-throw accuracy in 10 high-level basketball athletes, both in a non-fatigued state (Experiment 1) and immediately after an incremental running test completed until exhaustion (20 m shuttle run-test-Experiment 2). We collected perceived exhaustion and heart rate to quantify the subjective experience of fatigue and energy expenditure. We found that dMI brought better shooting performance than sMI, except when athletes were physically exhausted. These findings shed light on the conditions eliciting optimal use of sMI and dMI. In particular, considering that the current physical state affects body representation, performing dMI under fatigue may result in mismatches between actual and predicted body states.

Due to population aging, elderly drivers nowadays represent a significant rate of car drivers. Yet, we do not know exactly how aging may alter sensorimotor functions and therefore, its actual impact on safety. This paper aimed to assess to which extent elderly drivers are sensitive to various task loads and how this could impact reaction time with application to driving. Old and middle-aged people completed reaction time tasks (RT) close to those drivers usually have to manage while driving. We requested the participants to detect and respond to traffic lights or a traffic light arrows as quickly as possible during three experimental conditions of increasing difficulty. We expected that decision-making should be impacted through RT by manipulating the number of cues to be processed in both groups. The first test was a simple RT-task. The second and third tests were choice reaction time tasks requiring the processing of three or five information respectively. Responses had to occur within a 2s time-window, otherwise the result was considered a no-response. We showed that RT, error rate and no-response rate increased as a function of task difficulty, in both groups. However, the middle-aged people group outperformed the elderly group. RT difference between the two groups increased drastically with task difficulty. In the third test, the rate of no-response suggested that old drivers need more than 2s to process complex information and respond accurately. Both prolonged RT and no-response rate, especially for difficult tasks, may attest impairment of cognitive abilities, related to aging. Therefore, usual driving conditions for young drivers could be complex and stressful for the elderly who should thus be informed about the effects of normal aging upon driving with simple recommendations and advices.

Purpose Grasp recovery after C6-C7-spinal cord injury (SCI) requires learning "tenodesis grasp" whereby active wrist extension elicits passive thumb-to-forefinger and finger-to-palm flexion. Evidence that motor imagery (MI) promotes upper limb function after tetraplegia is growing, but whether MI potentiates grasp recovery in C6-C7-SCI individuals who have successfully learned the "tenodesis grasp" remains unknown. Methods Six chronic stable C6-C7-SCI inpatients and six healthy control participants were included. C6-C7-SCI participants imagined grasping movements and controls visualized geometric forms for 45 minutes, three times a week for five weeks. Three separate measures taken over a five week period before the intervention formed the baseline. Intervention effects were assessed immediately after the intervention and eight weeks later. Each testing session consisted of kinematic recordings during reach-to-grasp and magnetoencephalographic (MEG) recordings during wrist extension. Results During baseline, kinematic wrist extension angle during "tenodesis grasp" and MEG contralateral sensorimotor cortex (cSMC) activity during wrist extension were stable. Moreover, SCI participants exhibited a greater number of voxels within cSMC than controls. After MI sessions, wrist extension angle increased during "tenodesis grasp" and the number of voxels within cSMC during wrist extension decreased and became similar to controls. Conclusion These findings provide further support for the use of MI to reinforce a compensatory grasping movement (tenodesis) and induce brain plasticity.

Background Reduced physiological arousal in response to breath-holding affects internal clock processes, leading swimmers to underestimate the time spent under apnea. We investigated whether reduced physiological arousal during static apnea was likely to affect the temporal organization of motor imagery (MI). Methods Fourteen inter-regional to national breath-holding athletes mentally and physically performed two 15 m swimming tasks of identical durations. They performed the two sequences in a counterbalanced order, the first while breathing normally using a scuba, the second under apnea. We assessed MI duration immediately after completion of the corresponding task. Athletes performed MI with and without holding breath. Results MI durations (26.1 s ± 8.22) were significantly shorter than actual durations (29.7 s ± 7.6) without holding breath. Apnea increased MI durations by 10% (± 5%). Heart rate decrease in response to breath-holding correlated with MI durations increase (p

Dans les protocoles experimentaux portant sur l’imagerie motrice, la question de l’evaluation effective du travail mental effectue par les participants demeure une question recurrente pour le chercheur. De meme, le praticien doit pouvoir disposer de methodes lui permettant d’evaluer la qualite de l’imagerie motrice, qu’il soit entraineur et l’utilise a l’amelioration de la performance ou clinicien et en prescrive la pratique pour favoriser le recouvrement des fonctions motrices. Si les evaluations subjectives, faites par les participants, et la passation de questionnaires restent des outils frequemment utilises, on dispose aussi d’indicateurs physiologiques centraux et peripheriques. La neuroimagerie identifie les correlats structuraux et fonctionnels de l’imagerie motrice, mais cette methodologie n’est pas ambulatoire et reste reservee aux protocoles de laboratoire. Les indicateurs peripheriques apportent des signes objectifs du travail mental dont il faut traiter les donnees pour pouvoir les exploiter afin d’evaluer la qualite de l’imagerie. L’objectif de cet article est de presenter les caracteristiques et limites de ces familles methodologiques.

International audience; While the use of motor imagery (the mental representation of an action without overt execution) during actual training sessions is usually recommended, experimental studies examining the effect of physical fatigue on subsequent motor imagery performance are sparse and yielded divergent findings. Here, we investigated whether physical fatigue occurring during an intense sport training session affected motor imagery ability. Twelve swimmers (nine males, mean age 15.5 years) conducted a 45 min physically-fatiguing protocol where they swam from 70% to 100% of their maximal aerobic speed. We tested motor imagery ability immediately before and after fatigue state. Participants randomly imagined performing a swim turn using internal and external visual imagery. Self-reports ratings, imagery times and electrodermal responses, an index of alertness from the autonomic nervous system, were the dependent variables. Self-reports ratings indicated that participants did not encounter difficulty when performing motor imagery after fatigue. However, motor imagery times were significantly shortened during posttest compared to both pretest and actual turn times, thus indicating reduced timing accuracy. Looking at the selective effect of physical fatigue on external visual imagery did not reveal any difference before and after fatigue, whereas significantly shorter imagined times and electrodermal responses (respectively 15% and 48% decrease, p,0.001) were observed during the posttest for internal visual imagery. A significant correlation (r = 0.64; p,0.05) was observed between motor imagery vividness (estimated through imagery questionnaire) and autonomic responses during motor imagery after fatigue. These data support that unlike local muscle fatigue, physical fatigue occurring during intense sport training sessions is likely to affect motor imagery accuracy. These results might be explained by the updating of the internal representation of the motor sequence, due to temporary feedback originating from actual motor practice under fatigue. These findings provide insights to the co-dependent relationship between mental and motor processes.