Owaki T, Takeda T
Graduate School of Frontier Sciences, University of Tokyo, Japan.
Neurol Clin Neurophysiol. 2004 Nov 30;2004:107.
Multifocal visual evoked magnetic field (mfVEF) is useful for shortening the measurement time and/or improving the signal-to-noise ratio of recording, in investigating cortical activities elicited by multiple stimulus patches across the visual field. To record the whole-head mfVEF, we previously developed custom software to deliver multifocal stimuli and to analyze the acquired data, and we applied it to investigation of stereopsis. In the present study, relationship between mfVEF responses and binocular disparity was investigated. Subjects were instructed to fixate a nonius line in the center of a screen, and they were presented with rapid alteration of random-dot (RD) patches. The experiments consisted of a luminance change condition (condition L) and seven binocular disparity conditions (condition BDs) ranging from a crossed disparity of 1 deg to an uncrossed disparity of 1 deg. Each response evoked by one of the RD patches was obtained with the multifocal technique. Although all subjects showed obvious responses in the condition L, only one of the subjects showed obvious responses in condition BDs. The sources of the responses recorded in condition BDs were mainly localized around calcarine sulci according to the known retinotopic cortical representation. The responses obtained in condition BDs showed dependence on binocular disparity in the magnitude and the latency. These results would be the basis for further analysis of brain magnetic responses related to stereopsis.
多焦点视觉诱发电磁场（mfVEF）在研究由视野中多个刺激斑块引发的皮层活动时，对于缩短测量时间和/或提高记录的信噪比很有用。为了记录全头 mfVEF，我们之前开发了定制软件来呈现多焦点刺激并分析采集到的数据，并将其应用于立体视觉研究。在本研究中，我们研究了mfVEF反应与双眼视差之间的关系。受试者被指示注视屏幕中心的一条纳尤斯线，然后向他们呈现随机点（RD）斑块的快速交替。实验包括一个亮度变化条件（条件L）和七个双眼视差条件（条件BDs），范围从1度的交叉视差到1度的非交叉视差。通过多焦点技术获得由其中一个RD斑块引发的每个反应。尽管所有受试者在条件L下都表现出明显的反应，但只有一名受试者在条件BDs下表现出明显的反应。根据已知的视网膜皮层定位表示，在条件BDs下记录的反应源主要位于距状沟周围。在条件BDs下获得的反应在幅度和潜伏期上表现出对双眼视差的依赖性。这些结果将为进一步分析与立体视觉相关的脑磁反应奠定基础。
