Spatial and temporal dynamics of the networks for body motion processing

Body motion delivers a wealth of socially relevant information. Yet display inversion severely impedes biological motion (BM) processing. It is largely unknown how the brain circuits for BM are affected by display inversion. As upright and upside-down point-light BM displays are similar, we addressed this issue by using ultra-high-field functional MRI (at 9.4 tesla) providing for high sensitivity and spatial resolution. Whole-brain analysis along with exploration of the temporal dynamics of the BOLD response reveals that in the left hemisphere, inverted BM activates anterior networks engaged in decision making and cognitive control, whereas readily recognizable upright BM activates posterior areas solely. In the right hemisphere, multiple networks are activated in response to upright BM as compared to scarce activation to inversion. With identical visual input with display inversion, a large-scale network in the right hemisphere is detected in perceivers who do not constantly interpret displays as shown the ‘wrong way up’. For the first time, we uncover (i) (multi)functional involvement of each region in the networks underpinning BM processing, and (ii) large-scale ensembles of regions playing in unison with distinct dynamics. The outcome sheds light on the neural circuits underlying BM processing as an essential part of the social brain