Tool use acquisition induces a multifunctional interference effect during object processing: evidence from the sensorimotor mu rhythm

A fundamental characteristic of human development is acquiring and accumulating tool use knowledge through observation and sensorimotor experience. Recent studies showed that, in children and adults, different action possibilities to grasp-to-move and grasp-to-use objects generate a conflict that extinguishes neural motor resonance phenomena during visual object processing. In this study, a training protocol coupled with EEG recordings was administered in virtual reality to healthy adults to evaluate whether a similar conflict occurs between novel tool use knowledge. Participants perceived and manipulated two novel 3D tools trained beforehand with either single or double-usage. A weaker reduction of mu-band (10-13 Hz) power, accompanied by a reduced inter-trial phase coherence, was recorded during the perception of the tool associated with the double-usage. These effects started within the first 200 ms of visual object processing and were predominantly recorded over the left motor system. Furthermore, interacting with the double usage tool delayed grasp-to-reach movements. The results highlight a multifunctional interference effect, such as tool use acquisition reduces the neural motor resonance phenomenon and inhibits the activation of the motor system during subsequent object recognition. These results imply that learned tool use information guides sensorimotor processes of objects.