Related Experiment Video
Updated: Jun 10, 2026
Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
Attention modulates motor system activation during action observation: evidence for inhibitory rebound
Stefanie Schuch1, Andrew P Bayliss, Christoph Klein
1School of Psychology, Bangor University, Bangor, UK. schuch@psych.rwth-aachen.de
Abstract:
Perceiving another individual's actions activates the human motor system. We investigated whether this effect is stronger when the observed action is relevant to the observer's task. The mu rhythm (oscillatory activity in the 8- to 13-Hz band over sensorimotor cortex) was measured while participants watched videos of grasping movements. In one of two conditions, the participants had to later report how many times they had seen a certain kind of grasp. In the other condition, they viewed the identical videos but had to later report how many times they had seen a certain colour change. The colour change and the grasp always occurred simultaneously. Results show mu rhythm attenuation when watching the videos relative to baseline. This attenuation was stronger when participants later reported the grasp rather than the colour, suggesting that the motor system is more strongly activated when the observed grasping actions were relevant to the observer's task. Moreover, when the graspable object disappeared after the offset of the video, there was subsequent mu rhythm enhancement, reflecting a post-stimulus inhibitory rebound. This enhancement was again stronger when making judgments about the grasp than the colour, suggesting that the stronger activation is followed by a stronger inhibitory rebound.
Insights
Observing actions activates the human motor system, measured via mu rhythm (oscillatory activity). This motor system activation is stronger when observed grasping actions align with the observer's task relevance.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Motor Control
Background:
- The human motor system activates when observing actions.
- The degree of motor system activation may depend on the relevance of the observed action to the observer's current task.
Purpose of the Study:
- To investigate if observing actions leads to stronger motor system activation when the action is relevant to the observer's task.
- To examine the role of mu rhythm (8- to 13-Hz oscillatory activity over sensorimotor cortex) as an indicator of motor system engagement.
Main Methods:
- Participants watched videos of grasping movements under two conditions: reporting grasp type or reporting color change.
- Mu rhythm was measured during video observation and compared to baseline.
- Post-stimulus mu rhythm changes were analyzed following object disappearance.
Main Results:
- Mu rhythm showed attenuation during video observation, indicating motor system activation.
- This mu rhythm attenuation was significantly stronger when participants focused on the grasp compared to the color change.
- A subsequent mu rhythm enhancement (inhibitory rebound) was observed after the video, which was also stronger for grasp-relevant judgments.
Conclusions:
- The human motor system is more strongly activated by observed actions when those actions are relevant to the observer's task.
- Mu rhythm attenuation and subsequent enhancement reflect task-dependent motor system engagement and inhibitory rebound, respectively.
