title: Magnetic responses of human visual cortex to illusory contours.
abstract: To examine the neural mechanism underlying illusory-contour perception, we measured the magnetic responses of the human visual cortex to an abutting-line grating inducing illusory contours (test stimulus) and a non-abutting-line grating (control stimulus) using the technique of magnetoencephalography (MEG). In the initial latency period of 60-80 ms, the MEG response to the test stimulus was nearly identical with that to the control stimulus, but in the subsequent period of 80-150 ms, the former was larger than the latter. The origin of the peak MEG response to the test stimulus was estimated to be in the vicinity of striate cortex/extrastriate visual cortex for two of the four subjects. These results suggest that, in accord with those of the previous electrophysiological and functional magnetic resonance imaging studies, illusory-contour signals are generated in the very early stage(s) of processing in the primate visual cortex.
authors.affiliation: Faculty of Engineering and Design, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan. ohtani@hiei.kit.ac.jp
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Ohtani
authors.forename: Shoichi
authors.initials: S
authors.lastname: Okamura
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Shibasaki
authors.forename: Akira
authors.initials: A
authors.lastname: Arakawa
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Keisuke
authors.initials: K
authors.lastname: Toyama
authors.forename: Yoshimichi
authors.initials: Y
authors.lastname: Ejima
mesh_terms: D000328:Adult; D001931:Brain Mapping; D015350:Contrast Sensitivity / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D007088:Illusions / Q000502:physiology*; D015225:Magnetoencephalography; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology*