Jeffreys D A
Department of Communication and Neuroscience, Keele University, UK.
Exp Brain Res. 1996 Sep;111(1):79-99. doi: 10.1007/BF00229558.
This paper describes the first of two complementary studies designed to identify and to investigate the properties and likely functional significance of independently generated components of scalp-recorded responses evoked by stationary patterns. These experiments compared the influence of various stimulus parameters, including site of stimulation, pattern form, nature of background field and several binocular and monocular depth cues on a single subject's visual evoked potentials. The results revealed the presence, inter alia, of two topographically distinct components with the following properties. The earlier component (C2), whose polarity depends on the stimulus location in the visual field, is: contour-specific; best evoked by discrete pattern elements, but not gratings, in the central few degrees of the visual field; insensitive to any depth cues. By contrast, the later (consistently) negative potential (LNP) is not dependent on the form of the stimulus and is larger for paracentrally (beyond 1.5 degrees) than centrally located stimuli. It is also selectively enhanced by both monocular and binocular depth-cue stimuli, including the simulated forward movement of a pattern relative to a steady textured background; a stimulus which evokes no C2. The respective response properties of these scalp potentials suggest that there is parallel processing of depth- and contour-related features of stationary stimuli in anatomically separate regions of the human visual cortex.
本文描述了两项互补研究中的第一项，旨在识别并研究由静态图案诱发的头皮记录反应的独立产生成分的特性及其可能的功能意义。这些实验比较了各种刺激参数的影响，包括刺激部位、图案形式、背景场性质以及几种双眼和单眼深度线索对单个受试者视觉诱发电位的影响。结果尤其揭示了存在两种具有以下特性的地形上不同的成分。较早的成分（C2），其极性取决于视野中的刺激位置，具有以下特点：轮廓特异性；在视野中央几度范围内，由离散图案元素而非光栅能最佳诱发；对任何深度线索不敏感。相比之下，较晚出现的（始终）负电位（LNP）不依赖于刺激形式，对于位于旁中央（超过1.5度）的刺激比位于中央的刺激更大。它还被单眼和双眼深度线索刺激选择性增强，包括图案相对于稳定纹理背景的模拟向前运动；这种刺激不会诱发C2。这些头皮电位各自的反应特性表明，在人类视觉皮层的解剖学上分离的区域中，对静态刺激的深度和轮廓相关特征存在并行处理。
