Effect of imagined movement speed on subsequent motor performance

Researchers realize that motor imagery (MI) duration is closely linked to actual motor action duration. In 2 experiments, the authors investigated the effect of changing MI speed on actual movement duration over a 3-week training period. Experiment 1 involved 2 series of body movements that 24 participants mentally performed faster or slower than their actual execution speeds. The fast MI group's actual times decreased on subsequent performance. Participants in Experiment 2 were 21 skilled athletes who increased (decreased) their well-rehearsed actual movement times after MI training at a slow (fast) speed. The effect was task-related, however: MI affected only self-initiated movement. The effect of MI on actual speed execution supports the ideomotor theory because anticipation of sensory consequences of actions is mentally represented.     

When music tempo affects the temporal congruence between physical practice and motor imagery

When people listen to music, they hear beat and a metrical structure in the rhythm; these perceived patterns enable coordination with the music. A clear correspondence between the tempo of actual movement (e.g., walking) and that of music has been demonstrated, but whether similar coordination occurs during motor imagery is unknown. Twenty participants walked naturally for 8 m, either physically or mentally, while listening to slow and fast music, or not listening to anything at all (control condition). Executed and imagined walking times were recorded to assess the temporal congruence between physical practice (PP) and motor imagery (MI). Results showed a difference when comparing slow and fast time conditions, but each of these durations did not differ from soundless condition times, hence showing that body movement may not necessarily change in order to synchronize with music. However, the main finding revealed that the ability to achieve temporal congruence between PP and MI times was altered when listening to either slow or fast music. These data suggest that when physical movement is modulated with respect to the musical tempo, the MI efficacy of the corresponding movement may be affected by the rhythm of the music. Practical applications in sport are discussed as athletes frequently listen to music before competing while they mentally practice their movements to be performed.     

Daytime naps improve motor imagery learning

Sleep is known to contribute to motor memory consolidation. Recent studies have provided evidence that a night of sleep plays a similar functional role following motor imagery (MI), while the simple passage of time does not result in performance gains. Here, we examined the benefits of a daytime nap on motor memory consolidation after MI practice. Participants were trained by MI on an explicitly known sequence of finger movements at 11:00. Half of the participants were then subjected (at 14:00) to either a short nap (10 min of stage 2 sleep) or a long nap (60–90 min, including slow wave sleep and rapid eye movement sleep). We also collected data from both quiet and active rest control groups. All participants remained in the lab until being retested at 16:00. The data revealed that a daytime nap after imagery practice improved motor performance and, therefore, facilitated motor memory consolidation, as compared with spending a similar time interval in the wake state. Interestingly, the results revealed that both short and long naps resulted in similar delayed performance gains. The data might also suggest that the presence of slow wave and rapid eye movement sleep does not provide additional benefits for the sleep-dependent motor skill consolidation following MI practice.     

Impact of Neurologic Deficits on Motor Imagery: A Systematic Review of Clinical Evaluations

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 neurophysiological 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.     

Sleep-related improvements in motor learning following mental practice

A wide range of experimental studies have provided evidence that a night of sleep may enhance motor performance following physical practice (PP), but little is known, however, about its effect after motor imagery (MI). Using an explicitly learned pointing task paradigm, thirty participants were assigned to one of three groups that differed in the training method (PP, MI, and control groups). The physical performance was measured before training (pre-test), as well as before (post-test 1) and after a night of sleep (post-test 2). The time taken to complete the pointing tasks, the number of errors and the kinematic trajectories were the dependent variables. As expected, both the PP and the MI groups improved their performance during the post-test 1. The MI group was further found to enhance motor performance after sleep, hence suggesting that sleep-related effects are effective following mental practice. Such findings highlight the reliability of MI in learning process, which is thought consolidated when associated with sleep.     

Motor imagery and ‘placebo-racket effects’ in tennis serve performance

ObjectivesThis study aimed at confirming whether Motor Imagery (MI) enhances tennis serve performance, and determining whether a placebo condition could affect the beneficial effects of MI.DesignThis study used a 3 × 2 factorial design. Three groups of tennis players were compared in service performance outcomes before and after a training session.MethodsTwenty-two tennis players were assigned into three groups: a control (C) and two experimental groups subjected to a similar MI intervention, one group using their regular own racket (MI group) while the other used a placebo racket (P group).ResultsAnalyses of Covariance revealed no significant group difference when comparing serve velocity after training session, but MI training improved serve accuracy and regularity. Combining placebo racket with MI further resulted in greater serve accuracy score as compared to MI alone. Players' perception of their serve quality improved after MI, and this effect was reinforced in the P group.ConclusionThese findings revealed that MI may be useful to achieve peak performance, and that the implement placebo effect might be a factor in sport performance, hence promoting the beneficial effects of alternative methods to improve tennis serve performance.     

Field dependence-independence in complex motor skills

This study analyzed the relationship between field dependence-independence and complex motor skills. According to the requirements of each sporting activity, subjects' motor system can be mainly controlled through exteroceptive or proprioceptive information. Sport performances require the athlete to disembed himself, other players, or the ball from the background, and decision-making appears to require cognitive restructuring. 26 athletes (13 men and 13 women) involved in acrobatic sports (gymnastics, trampoline, half-pipe snowboard, synchronized 3-m springboard, acrobatic rock, skateboard, and free skating) and 26 athletes (13 men and 13 women) involved in individual racket sports (tennis and table-tennis) completed the Group Embedded Figures Test. Participants (at least 10 years of practice) were from 16 to 35 years of age (M=22.0, SD=3.1). No significant difference among athletes on scores for field dependence-independence was evidenced given this expertise, sex, or age. Significantly higher scores were obtained by athletes in acrobatic sports, indicating that they tended to be predominately more field-independent whereas the lower scores were obtained by tennis and table-tennis players.     

Expertise and peripheral autonomic activity during the preparation phase in shooting events

This study compared effectiveness of the concentration period in two groups of shooters to evaluate the influence of their expertise while concentrating on the target. Marksmen (pistol shooters, 10 men and 5 women) and pentathletes (6 men and 7 women) took part in a shooting competition in keeping with the rules of each event. Participants were then asked to imagine themselves shooting, at the laboratory. Five variables representing the activity of the autonomic nervous system were continuously recorded (skin resistance and potential, skin blood flow, skin temperature, instantaneous heart rate). Autonomic responses recorded during concentration, actual shooting, and mental imagery were compared by calculating the ratios concentration/ shooting and imagery/shooting. The resultant mean ratio was used to characterize each participant. The same autonomic nervous system pattern was observed during concentrating on the target, mental imagery, and actual shooting. However, marksmen showed ratios closer to 1.0 than pentathletes, absolute mean differences being .06 and .3, respectively. Shorter duration and weakest amplitude responses were recorded during the concentration phase in the Pentathlete group, suggesting that they have more difficulty in using mental imagery during competition than marksmen. When subjects performed well, a specific response pattern was observed in the Marksman group, but not in the Pentathlete group, except in skin potential. In both Marksman and Pentathlete groups, a majority of negative skin potential responses were found in the concentration and shooting phases for the best shots.     

An integrated device to evaluate a driver’s functional state

In the field of cognitive ergonomics, research on car drivers requires multimodal in-vehicle systems for recording not only driving-related behavior, but also contextual information from their surroundings. In addition, reliable information concerning a driver’s functional state should be obtained. In this article, we describe an integrated device simultaneously recording specific physiological data, video recordings of the driver and environment, parameters from the vehicle, and contextual data. Physiological signals from the autonomic nervous system provide objective and quantitative information on the driver’s alertness and his/her ability to process specific driving-related stimuli or other nonspecific information. Consequently, recorded physiological responses can be related to individual driving events. Electrodermal and cardiac activities are sensitive to time-dependent variations in arousal level and to certain external stimuli, so there is great interest in studying drivers’ behavior via measured physiological signals that have been established as suitable behavioral indicators. The present integrated device is capable of processing the relevant indices from raw measured data in real time.     

Motor interference does not impair the memory consolidation of imagined movements

The present study aimed to investigate whether an interference task might impact the sleep-dependent consolidation process of a mentally learned sequence of movements. Thirty-two participants were subjected to a first training session through motor imagery (MI) or physical practice (PP) of a finger sequence learning task. After 2 h, half of the participants were requested to perform a second interfering PP task (reversed finger sequence). All participants were finally re-tested following a night of sleep on the first finger sequence. The main findings revealed delayed performance gains following a night of sleep in the MI group, i.e. the interfering task did not alter the consolidation process, by contrast to the PP group. These results confirm that MI practice might result in less retroactive interference than PP, and further highlight the relevance of the first night of sleep for the consolidation process following MI practice. These data might thus contribute to determine in greater details the practical implications of mental training in motor learning and rehabilitation.