The role of kinematics in cortical regions for continuous human motion perception.

It has been proposed that we make sense of the movements of others by observing fluctuations in the kinematic properties of their actions. At the neural level, activity in the human motion complex (hMT+) and posterior superior temporal sulcus (pSTS) has been implicated in this relationship. However, previous neuroimaging studies have largely utilized brief, diminished stimuli, and the role of relevant kinematic parameters for the processing of human action remains unclear. We addressed this issue by showing extended-duration natural displays of an actor engaged in two common activities, to 12 participants in an fMRI study under passive viewing conditions. Our region-of-interest analysis focused on three neural areas (hMT+, pSTS, and fusiform face area) and was accompanied by a whole-brain analysis. The kinematic properties of the actor, particularly the speed of body part motion and the distance between body parts, were related to activity in hMT+ and pSTS. Whole-brain exploratory analyses revealed additional areas in posterior cortex, frontal cortex, and the cerebellum whose activity was related to these features. These results indicate that the kinematic properties of peoples' movements are continually monitored during everyday activity as a step to determining actions and intent.