Abstract
While neuroscientific and behavioral studies indicate that the intention to properly use, transmit, or displace a tool may engage different mechanisms in the brain, no study has directly compared activation patterns associated with the control of actions motivated by such distinct goals. Here, we used functional magnetic resonance imaging to establish the neural underpinnings of planning and execution of visually-guided grasps with different intentions in mind. Brain activity was measured in an event-related design (cf. Króliczak & Frey, 2009) while 20 right-handers performed the following tasks with their dominant hands: (1) planning grasps directed at tools with an intention to (A) functionally use them, or (B) to pass them to a different person; (2) planning reaching movements directed at tools with an intention to move them with the back of the hand, and (3) pantomimed execution of the planned actions (grasping/reaching movements). A 1-s intention cue (a shape of different color) was followed by a 1.5-s tool image, a variable delay period, a 1.5-s action cue, and a variable inter-trial interval. The stimuli were high-resolution images of graspable tools presented at three different angles in their foreshortened views, emulating 3D viewing. Using a contrast of planning to grasp a tool irrespective of intentions vs. to move a tool, we first identified the praxis representation network (PRN). Subsequent contrast between planning grasping-to-pass vs. grasping-to-use actions showed greater activity in subdivisions of PRN, including the left supramarginal and middle frontal gyri. In the inverse contrast, one of the key modulations was found primarily in the left retrosplenial cortex. Thus, although object-affordance processing is not required to pass a tool, the areas traditionally associated with tool use were nevertheless invoked more. Unexpectedly, therefore, our results demonstrate that the greater engagement of key subdivisions of PRN is not specific to tool-use actions.
Meeting abstract presented at VSS 2015