Effects of stimulus field size and coherence of visual motion on cortical responses in humans: an MEG study

Among various kinds of visual motion, wide field coherent visual motion should have characteristic physiological significance regarding the relationship between the external world and us. To detect veridical visual motion in the surrounding environment, specific mechanisms are necessary to differentiate it from the wide field coherent motion due to one's own movement. To disclose whether and how the neural process of wide field coherent motion is different from that of other motions, we measured cortical responses to visual motions in humans using magnetoencephalography (MEG) manipulating both field size and coherence. Results showed that an increase in field size enhanced the response at sensors around the parieto-occipital area, and that the difference in activity between coherent and incoherent motion tended to be larger for the wide field. These findings suggest that wide field coherent and incoherent motion is detected differently at least in part in the parieto-occipital area, and suggest the neural process of wide field coherent motion could be pronouncedly tapped by a combination of field size and coherence.