1,721,037 research outputs found
Time perception of visual motion is tuned by the motor representation of human actions
No full textSeveral studies have shown that the observation of a rapidly moving stimulus dilates our perception of time. However, this effect appears to be at odds with the fact that our interactions both with environment and with each other are temporally accurate. This work exploits this paradox to investigate whether the temporal accuracy of visual motion uses motor representations of actions. To this aim, the stimuli were a dot moving with kinematics belonging or not to the human motor repertoire and displayed at different velocities. Participants had to replicate its duration with two tasks differing in the underlying motor plan. Results show that independently of the task's motor plan, the temporal accuracy and precision depend on the correspondence between the stimulus' kinematics and the observer's motor competencies. Our data suggest that the temporal mechanism of visual motion exploits a temporal visuomotor representation tuned by the motor knowledge of human actions
The tool as the last piece of the athlete's gesture imagery puzzle.
No full textThe present study tested whether and how motor experience with a specific tool affects motor representation of a specific movement. To this aim, we considered a group of expert tennis players and a control group of athletic individuals without tennis experience. Participants were asked to execute 20 single forehands into the wall with a tennis racket (movement execution - ME) and, afterward, to produce a kinesthetic image of themselves while executing the same movements (motor imagery - MI). During MI participants handled one of the following tools: a tennis racket, a tennis-like racket and an umbrella. Results showed that the duration of the real and the imagined movements were almost similar when participants of both groups held the tennis rackets. In contrast, when tennis players handled the tools not specific for tennis the duration of the imagined movements increased significantly compared to the MI duration with a tennis racket. On the opposite, the handled tool did not modulate MI performances of the control group. In conclusion, this study showed that motor representation of subjects who developed motor skills associated to tool-use is reliant on the object used to practice movements. This finding suggests that, although MI mainly relies on the activity of cortical motor regions, non-motor information - as the use of the tool to practice movement - strongly affects the MI performance
Action observation combined with peripheral electrical nerve stimulation increases motor efficiency
No full textLearning by observing: the effect of multiple sessions of action-observation training on the spontaneous movement tempo and motor resonance
No full textThe present study was designed to explore the changes in motor performance and motor resonance after multiple sessions of action observation (AO) training. Subjects were exposed to the observation of a video showing finger tapping movements executed at 3Hz, a frequency higher than the spontaneous one (2Hz) for four consecutive days. Motor performance and motor resonance were tested before the AO training on the first day, and on the last day. Results showed that multiple sessions of AO training induced a shift of the speed of execution of finger tapping movements toward the observed one and a change in motor resonance. Before the 3Hz-AO training cortical excitability was highest during the observation of the 2Hz video. This motor resonance effect was lost after one single session of 3Hz-AO training whereas after multiple sessions of 3Hz-AO training cortical excitability was highest during the observation of the 3Hz video. Our study shows for the first time that multiple sessions of AO training are able not only to induce performance gains but also to change the way by which the observer's motor system recognizes a certain movement as belonging to the individual motor repertoire. These results may encourage the development of novel rehabilitative protocols based on multiple sessions of action observation aimed to regain a correct movement when its spontaneous speed is modified by pathologies or to modify the innate temporal properties of certain movements
Observing suboptimal movement schemas: EEG evidences for progressive sensorimotor integration
No full textObjective
Action observation is known to enhance sensorimotor system activation, and such effect has been linked to neural priming and response facilitation mechanisms. Moreover, visuo-motor facilitation and action observation processes proved to be influenced by expertise. The role of expertise, however, has been primarily studied by focusing on high-level motor proficiency. As a consequence, while it was shown that the observation of trained sport gestures is able to induce greater motor responsivity in athletes, evidences on the effect of observing poorly performed actions are still lacking. On the basis of a preliminary TMS study suggesting that motor cortex activity can be modulated even by the observation of suboptimal movement performances, we investigated electrophysiological (EEG) correlates of the observation of complex actions performed by healthy individuals and patients affected by multiple sclerosis (MS).
Participants
Twenty healthy young adults took part in the study and were presented with four randomly reiterated videos. Videos depicted a healthy confederate, a minimally-impaired MS patient, a mildly-impaired MS patient, or a confederate trying to simulate mild motor difficulties performing a test tapping on fine motor abilities. EEG data were recorded and analysed in the frequency-domain and across video reiterations.
Results
The time-series analysis of EEG frequency data highlighted globally lower beta power during the observation of patients’ videos with respect to confederate’s videos, even when he simulated poor motor performances. Further, we observed gradually increasing beta activity across videos reiterations, but specifically over somatosensory regions and for the minimally-impaired patient’ video.
Conclusion
We suggest that such evidences mirror a progressive integration of slightly suboptimal motor performances into participants’ motor schemata and that they further hint at the innate sensitivity and responsivity of the sensorimotor system, in line with evidences associating EEG beta desynchronization with processing of observed and executed goal-directed actions
Early adaptation to high‐altitude: Mood and cognitive responses at simulated 4500 m
Full text linkAbstract High‐altitude exposure induces hypoxemia, triggering metabolic adjustments to enhance oxygen delivery. This acclimatization process often involves mood changes, cognitive alterations, and Acute Mountain Sickness (AMS) symptoms. This study examined the effects of simulated hypoxia at 4500 m on physiological variables, reaction time, lapses, and mood states. Twenty‐three volunteers were exposed to a simulated 4500 m altitude for 4 h in a normobaric hypoxia chamber. Lactate, glucose, SpO2, heart rate (HR), and AMS symptoms were assessed before and every hour during exposure. As expected, SpO2 significantly decreased (p < 0.001), while HR increased (p = 0.006) during exposure. Reaction time remained unaffected, but lapses significantly correlated with lactate levels (p = 0.002). Mood states, particularly tension (p = 0.001) and fatigue (p < 0.001), were associated with AMS symptoms. Simulated high‐altitude exposure induced physiological alterations, including decreased SpO2, increased HR, and a significant correlation between lactate levels and cognitive performance. While reaction time was unchanged, mood disturbances were strongly related to AMS. These findings highlight the need for strategies to mitigate both physiological and psychological effects of hypoxia
This racket is not mine: The influence of the tool-use on peripersonal space
No full textThe aim of the present study was to test whether the peripersonal space (PPS), defined as the portion of the space immediately surrounding the body, is modulated by the long-term motor experience with a specific tool in a sportsmen population. To this end, we evaluated, by means of a multisensory integration paradigm, how tennis players and novices to the sport of tennis perceived the PPS while holding a tennis racket. Going deeply, in the case of the athletes, we tested the effect of their personal racket, i.e., the one they regularly use during their sport activities, compared to a common one. When handling one of these objects or nothing, participants were requested to verbally respond to a tactile stimulus administered at the right wrist while hearing a task-irrelevant sound emitted by a speaker positioned either near to the hand (Near) or far from it (Far). Reaction time to a tactile stimulus associated with the Far sound were higher than those associated with the Near sound when tennis players and novices held the common racket, whereas this difference disappeared when the athletes handled the personal tennis racket. These results suggest that the tool daily used during sport activity is stably embodied in the peripersonal space of tennis players
Automatic versus voluntary motor imitation: effect of visual context and stimulus velocity.
No full textAutomatic imitation is the tendency to reproduce observed actions involuntarily. Though this topic has been widely treated, at present little is known about the automatic imitation of the kinematic features of an observed movement. The present study was designed to understand if the kinematics of a previously seen stimulus primes the executed action, and if this effect is sensitive to the kinds of stimuli presented. We proposed a simple imitation paradigm in which a dot or a human demonstrator moved in front of the participant who was instructed either to reach the final position of the stimulus or to imitate its motion with his or her right arm. Participants' movements were automatically contaminated by stimulus velocity when it moved according to biological laws, suggesting that automatic imitation was kinematic dependent. Despite that the performance, in term of reproduced velocity, improved in a context of voluntary imitation, subjects did not replicate the observed motions exactly. These effects were not affected by the kind of stimuli used, i.e., motor responses were influenced in the same manner after dot or human observation. These findings support the existence of low-level sensory-motor matching mechanisms that work on movement planning and represent the basis for higher levels of social interaction
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