The present work aimed at exploring functional correlates of motor and linguistic representations of everyday actions, with a specific interest in potential sensorimotor activation effects induced by the use of related action sentences. While it is indeed known that observing simple motor acts (e.g., precision grasping) and listening to the sound of specific actions (e.g., walking) activate sensorimotor structures, less is known when we move to more complex behaviors and more abstract linguistic representations (e.g., verbal descriptions). Again, the potential of linguistic representations to facilitate the activation of specific sensorimotor structures during action execution or observation is yet unexplored. We then aimed at investigating hemodynamic activation patterns (via functional near-infrared spectroscopy, fNIRS) within the sensorimotor network during different tasks based on everyday activities. Twenty volunteers were asked to execute (EXE), observe (OBS), or listen (LIS) to brief verbal descriptions of transitive actions, to observe them while listening to their description (OBS–LIS), or to execute them while listening to their description (EXE–LIS). Analyses highlighted that, in the left hemisphere, hemodynamic responses were the lowest during observation of complex actions and observation coupled with listening, greater during simple listening to verbal description of actions, and maximal when participants actually executed complex actions or executed them while listening to their verbal descriptions. The present results suggest that processing verbal descriptions of actions might keep the sensorimotor network more active than simply observing them. Such first pieces of evidence hint at potential implications for novel procedures for rehabilitation of movement and action deficits.
Linguistic representation Action execution Action observation fNIRS Sensorimotor network Embodied language
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Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.
Informed consent was obtained from all individual participants included in the study.
Group waveforms and topographical maps of task-related hemodynamic responses relative to action observation (OBS), observation and listening (OBS–LIS), listening (LIS), execution and listening (EXE–LIS), and execution (EXE) conditions. (a) O2Hb (red lines) and HHb (blue lines) waveforms (grand averages) during different experimental conditions; right channels; shaded areas represent ±1 SE from the mean. (b) Topographical activation maps for O2Hb-related measures; green-to-blue colors mark a decrease in oxygenated hemoglobin concentration; green-to-red colors mark an increase in oxygenated hemoglobin concentration (TIF 3385 KB)