Neural Interactions between Dorsal and Ventral Visual Subsystems While Perceiving 3-D Structure from 2-D Motion

Abstract

Two-dimensional optic flow is an important cue to perceive 3D structure of objects. Recent neuroimaging studies suggest the involvement of both the ventral and the dorsal visual pathways in the perception of 3D structure from motion (3D-SFM), though the neural dynamics underlying the 3D-SFM is not fully understood. Here, we combine magnetoencephalography (MEG) and fMRI to detect the dynamic brain responses to 3D-SFM. We manipulated the coherence of randomly moving dots to create different levels of 3D perception and investigated the associated changes in brain activity. Results of the fMRI analysis were used to impose plausible constraints on the MEG inverse calculation to improve spatial resolution of the spatiotemporal activity estimates. Time-frequency analysis was also employed to elucidate spatio-temporal dynamic changes in the spontaneous brain activities.

MEG-fMRI combined analysis showed that the activities the posterior infero-temporal (pIT), parieto-occipital (PO), and intra-parietal (IP) regions were increased at different latencies during highly coherent motion conditions in which subjects perceived a robust 3D object. Results of the time-frequency analysis indicated the suppression of alpha- and beta-band activities in these regions which reflect the commitment of these areas in the perception of 3D-SFM. Current results suggest that the interactions between the dorsal and ventral visual subsystems are crucial for the perception of 3D object from 2D optic flow.