Biological motion processing: An fMRI study

Purpose. To identify the neural substrates of biological motion processing in humans -possibly a region homologous to the Superior Temporal Polysensory area (STP) in the monkey. Methods. Functional MR images were acquired using a T2*-weighted spiral acquisition pulse sequence while subjects viewed an alternating pattern of a human 'point-walker' with a scrambled version of the same stimulus (preserving the local motion vectors). In the same session, subjects also viewed a series of faces alternating with band-limited white noise patterns. The first experiment was designed to localize area STP whereas the second experiment was used to identify temporal regions sensitive to faces. Results. Regions of activation were found in the occipito-temporal border (in lateral regions or deep within the sulci) for the biological motion stimulus whereas the face stimulus activated regions largely restricted to the ventral portions of the occipito-temporal border. Conclusions. Separate extra-striate regions responsive to faces and biological motion were identified. Thus, we were able to functionally dissociate an STP-like area from neighboring extra-striate regions that likely correspond to inferotemporal cortex.