Abstract
During action observation, several visual features of observed actions can modulate the level of sensorimotor reactivity in the onlooker. Among possibly relevant parameters, one of the less investigated in humans is the visual perspective from which actions are observed. In the present EEG study, we assessed the reactivity of alpha and beta mu rhythm subcomponents to four different visual perspectives, defined by the position of the observer relative to the moving agent (identifying first-person, third-person and lateral viewpoints) and by the anatomical compatibility of observed effectors with self- or other individual’s body (identifying ego- and allo-centric viewpoints, respectively). Overall, the strongest sensorimotor responsiveness emerged for first-person perspective. Furthermore, we found different patterns of perspective-dependent reactivity in rolandic alpha and beta ranges, with the former tuned to visuospatial details of observed actions and the latter tuned to action-related parameters (such as the direction of actions relative to the observer), suggesting a higher recruitment of beta motor rhythm in face-to-face interactions. The impact of these findings on the selection of most effective action stimuli for “Action Observation Treatment” neurorehabilitative protocols is discussed.
Highlights
To date, ample evidence suggests that the observation of actions performed by another individual can automatically activate cortical motor networks similar to those involved in the actual performance of the observed action, through the so-called Mirror Neurons System (MNS)[1,2,3]
One-tailed single-sample t tests against 0 resulted significant (FP t(15) = −10.62, lateral allocentric perspective (LA) t(15) = −11.98, lateral egocentric perspective (LE) t(15) = −14.04, third-person perspective (TP) t(15) = −11.09; all ps < 0.001), proving that during action observation (AO) all perspectives induced an overall significant suppression of alpha mu subcomponent with respect to the baseline
One-tailed single-sample t tests against 0 resulted significant (FP t(15) = −8.85, LA t(15) = −8.75, LE t(15) = −9.41, TP t(15) = −7,53; all ps < 0.001), proving a significant suppression of beta mu subcomponent relative to the baseline during AO from all perspectives
Summary
Ample evidence suggests that the observation of actions performed by another individual can automatically activate cortical motor networks similar to those involved in the actual performance of the observed action, through the so-called Mirror Neurons System (MNS)[1,2,3]. In allocentric perspectives visual information is anatomically congruent only with the body parts of another individual Combining these coordinates systems, both longitudinal and lateral perspectives can be labelled as either ego- or allo-centric. Seeing a right hand from the right side of a moving agent represents a lateral allocentric perspective (LA), since this viewpoint precludes a direct spatial and morphological matching with the view of body parts of the observer. Stronger desynchronization of alpha mu subcomponent during observation of hand actions from TP compared to FP has been reported[13] This result has been interpreted as reflecting higher processing load required by TP to match perceived movements with the observer’s egocentric frame of reference. The choice of such points of view was empirical, since conclusive evidence about which perspective is the most effective in priming the motor system is still lacking
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
