Abstract
It has been recently reported that there are posterior hemispheric differences in brain neural activity in response to normal biological motion of human walking versus scrambled versions of the same displays where a walker was not visible. In our study we investigated neural electrical responses resulting from the introduction of temporal offset noise into the joint angles of complex human ballet movements. The introduction of such noise results in a human figure being visible at each frame, but the coordination of the movement is disrupted. By introducing more noise into all segments of the body we were able to create displays with less apparent coordination among the limbs. Movement duration of the ballet stimuli was fixed at 2 sec. Each of16 movies (4 movements × 4 noise levels, including 0) were presented for 35 trials, resulting in a total of 560 trials. We displayed the movements to naïve observers and asked them to judge whether a movement was possible or not by rating it on 4 point scale that varied from definitely possible to definitely impossible. ERP responses were recorded from 62 electrodes. Results showed that the intact biological motions elicited anterior parietal late electrical responses in the right hemisphere. In addition, a latency difference was found in the early and late parietal responses between the different levels of noise. The intact movements elicited pronounced responses. In light of previous neuroimaging results we speculate that firstly the results are consistent with the involvement of the STS in the perception of biological motions. Secondly, that the right posterior area is involved in the further cognitive evaluation of information related to complex human movements.
EC grant HPRN-CT-2002-00226