Influence of goals on observation of actions: Functional neuroimaging studies

Mentalising or Theory-of-Mind (ToM) is defined as the attribution of mental states to other agents. While this capacity develops progressively in children, an important step is reached by passing the false-belief task, normally at about four years of age. Measures of brain activity during performance of a wide range of tasks requiring ToM have repeatedly demonstrated involvement of a particular set of brain regions. But how each of these regions contributes to this process is not yet clear. Based on previous data and a model of the cognitive components necessary for ToM, I performed three experiments using event-related functional magnetic resonance imaging in healthy volunteers to clarify the involvement of brain regions in important components of the ToM capacity. Two different cognitive processes were studied: 1) the identification of potential living entities in the environment and 2) the observation of human actions. In both types of processes, one variable appears to play an important role according to the literature; the presence of goals in the observed actions. This variable was therefore manipulated in all experiments. When healthy subjects watched two disks, moving in a seemingly animate way, interact with each other, activity in a region known to respond to biological motion (the posterior part of the superior temporal sulcus area, or pSTS) increased parametrically with the presence of a goal in the behaviour of the disks, as did attribution of animacy. In a second experiment using moving disks, the pSTS showed greater activation when a chasing disk appeared to attribute goals to the target rather than simply following it. The third experiment showed a role of the pSTS in the analysis of human movement kinematics during categorisation of actions depending on goal-directedness. The role of goals in the neural basis of mentalising is discussed