Network analysis for the visual information processing by magneto encephalography

脑磁图（MEG）是一种非侵入性的视觉信息处理方法。1.图形反转视觉诱发电位（VEP）的神经发生器：瞬态VEP由N75、P100和N145组成。我们估计的VEP电流偶极子的位置，以澄清他们的神经发生器。脑磁图的源性定位表明，所有的三个组成部分都位于距状裂周围。其中P100的来源最为可靠。根据我们的结果，N75和P100可能产生于纹状体皮质。虽然我们的研究表明N145也可能在V1中产生，但还需要进一步的研究。2.大细胞和小细胞系统的并行加工：大细胞系统在运动知觉中起重要作用，而小细胞系统在色觉和形觉中起重要作用。我们用一个视运动显示器和等亮度的红绿正弦光栅有选择地模拟了这两个系统。视运动诱发P120，而彩色光栅显示N120。这些偶极子估计在纹状视皮层，这表明有一个平行的处理在初级视觉皮层。3.神经系统疾病的患者：一些神经系统疾病有视觉缺陷，如不能和色盲。不幸的是，由于时间有限，我们无法检查这些患者。

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.