Wurm et al. (2014)

Abstract:
Actions are usually made of several action steps gearing towards an overarching goal. During observation of such action episodes the overarching action goal becomes more and more clear and upcoming action steps can be predicted with increasing precision. To tap this process, the present fMRI study investigated the dynamic changes of neural activity during the observation of distinct action steps that cohere by an overarching goal. Our hypotheses specifically addressed the role of the inferior frontal gyrus (IFG), a region assumed to be a key hub for integration functions during action processing, as well as the role of regions involved in action perception (often referred to as action observation network or AON) that should benefit from the predictability of forthcoming action steps. Participants watched separate action steps that formed a coherent action goal or not (factor goal coherence) and were performed by a single actor or not (factor actor coherence). Independent of actor coherence, neural activity in IFG and occipitotemporal cortex decreased as a function of goal predictability during the unfolding of goal coherent episodes. In addition, we identified a network (precuneus, dorsolateral prefrontal and orbitofrontal cortex, angular gyrus, and middle temporal gyrus) that showed increased activity for goal coherence. We conclude that IFG fosters the integration of action steps to build overarching goals. Identifying the unifying goal of an action episode allows anticipation, and thus efficient processing, of forthcoming action steps. To this end, past action steps of the action episode are buffered and recollected with recourse to episodic memory.