1-A-D-20. Spatiotemporal dynamics of neuromagnetic oscillations related to the illusory motion perception

Abstract

Rotating snakes (RS) image yields illusory rotatory motion for the observers. We studied spatiotemporal dynamics of the neuromagnetic oscillations that underlie the rotatory illusion. Thirteen healthy young adults participated in this study. They were repeatedly presented RS and stationary images for 5 s in random order with the inter-stimulus interval of 2 s. Neural activities were recorded by a 306-ch magnetoencephalography (MEG). The participants were required to press a computer mouse button as quickly as possible whenever the illusory motion was perceived and to stop the button pressing when this perception ended. MEG data were analyzed by a time–frequency analysis (Wavelet transformation) and a DICS beamformer source localization method. In the grand averaged data, alpha- and beta-band neuromagnetic activities at the bilateral temporal regions to RS image tended to be more desynchronized than those of the stationary image. This event-related desynchronization arose at about 500 ms before the participants reported the illusory motion perception. Furthermore, their sources were estimated in the areas including hMT/V5+. Our results clearly demonstrated the temporal profile of the illusory motion perception, which suggests that the illusory motion of RS image is linked to the function of hMT/V5+.