An fNIRS investigation of perceptual, motor and linguistic representations of complex actions

Objective The present work aimed at exploring potential associations and similarities of perceptual, motor and linguistic representations of complex real-life actions, with a specific interest in potential sensorimotor activation effects induced by the observation of such behaviors or the use of relative action verbs. 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 representations (e.g. verbal description, action verbs). We then aimed at investigating hemodynamic activation patterns of the sensorimotor network during different action-related tasks based on complex every-day activities. Participants and methods 20 volunteers were asked to actually execute, observe, or listen to brief verbal descriptions of complex goal-directed real-life actions, or, again, to observe them while listening to their description or to execute them while listening to their description. Cortical functional data have been collected via optical imaging (functional Near-Infrared Spectroscopy - fNIRS). Results The analysis of fNIRS data highlighted that, in the left hemisphere (contralateral to target actions), hemodynamic responses were the lowest during observation of complex actions and observation coupled with listening of consistent simple verbal description of actions, greater during simple listening of verbal description of actions, and maximal when participants actually executed complex actions and when they executed them while listening to consistent simple verbal descriptions. Conclusion Present results suggest that listening to verbal description of actions might keep the sensorimotor network more active than simply observing them, and that coupling execution of complex action with listening of their description similarly recruit sensorimotor regions with respect to simple action execution. Such first evidences hint at potential implication for novel rehabilitation procedures of movement and action deficits.