Disentangling the neural bases of action intentions: evidence from fMRI studies.

The way we interact with manipulable objects varies substantially depending on the goal of the intended action. Surprisingly, very little is known about the neural underpinnings of planning disparate actions and interactions taken with tools, e.g., whether or not the praxis representation network (PRN) of the left cerebral hemisphere is involved in each case. To address this issue, in a series of functional magnetic resonance imaging (fMRI) studies involving both event-related and block-design paradigms, brain activity was measured while twenty (20) right-handed participants - using either their right or left hands - processed images of tools with the following intentions: (1) to subsequently use them according to their functions, (2) to pass them to a different person, (3) to simply move the tool in front of them with the back of their hands, or (4) to move the tool by grasping and putting the object aside. Counter to the hypothesis that PRN would be involved more in, or would mediate primarily, intentions related to the planning of the actual use of tools, we report convincing evidence showing that the crucial nodes of this network - the left supramarginal and middle frontal gyri - are engaged significantly more in preparation for actions that are not use related. This is the case both at the hand-dependent, i.e. separately for the right and left hand, as well as at hand-independent level of analyses. These findings shed a new light on how different goals and/or contexts influence the perception of object affordances, and to what extent they modulate the fMRI activity within the parieto-frontal action networks and beyond them. Meeting abstract presented at VSS 2015