Network analysis for the visual information processing by magneto encephalography

点击翻译按钮获取中文摘要

Visual information processing has been studied non-invasively by using magnetoencephalography (MEG). The following results were obtained.1.Neural generators of pattern reversal visual evoked potentials (VEPs) : Transient VEPs consist of N75, P100 and N145. We estimated location of the current dipoles of VEPs in order to clarify their neural generators. Source localization by the MEG indicated that all the three components were located around the calcarine fissure. The source of P100 was most reliable among the components. Based on our results, N75 and P100 may be generated in the striate cortex. Although our study suggests that N145 may also be generated in V1, further study is necessary.2.Parallel processing by magnocellular and parvocellular systems : Magnocellular system plays an important role for motion perception while parvocellular system in color vision and form perception. We stimulated these two systems selectively by using an apparent motion display and isoluminant red-green sinusoidal gratings. The apparent motion evoked P120 while chromatic gratings showed N120. These dipoles were estimated in the striate visual cortex, suggesting that there is a parallel processing within the primary visual cortex.3.Patients with neurological disorders : Some neurological disorders have visual deficits such as akinetopsia and achromatopsia. Unfortunately, we could not examine such patients due to the limited time schedule.