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Abstract

Body motion (BM) is a rich source of information for social cognition and interaction. Yet display inversion severely impedes BM processing. It is still unclear how brain networks underpinning BM processing are affected by display inversion. To address this issue, we used ultra-high field
functional magnetic resonance imaging (fMRI) at 9.4T. Participants performed a two-alternativeforced-choice task, indicating whether an upright point-light walker or control displays (the same movie inverted 180 deg) were presented. An upright walker elicits most pronounced clusters of
fMRI activity in the bilateral superior occipital cortices and the right middle temporal cortex, whereas the inverted display results in bilateral activity of lower occipital cortices, primarily, the lingual cortices. The BOLD response in these areas exhibited specific temporal dynamics during stimulus duration: a decrease in activation in the second 5 s of stimulus duration, with a recurrent
increase afterwards. Perceivers who did not recognize upside-down display as a walker exhibit activity in the distributed network with hubs in the right hemisphere including the lingual and postcentral cortices, and the pars operculum. The outcome provides novel insights on the brain networks underlying body motion processing and its functional neuroanatomy.