Zak R, Berkley M A
Vision Res. 1986;26(3):439-51. doi: 10.1016/0042-6989(86)90187-2.
The characteristics of the neural generator producing an evoked potential in response to the brief presentation of a vernier offset was investigated in three experiments. In the first study, averaged evoked potentials (EPs) recorded in response to a single vernier offset stimulus consisting of a horizontal line which changed from colinearity to noncolinearity for 100 msec every 1.5 sec were compared to responses elicited by other vernier configurations consisting of: stimuli with multiple offsets; stimuli presented in different orientations; targets with different offset features; and with the simple displacement of a colinear line. The results showed that a single vernier offset elicited a robust response if the offset was located in the central zone (1 degree) of the target. Other features of the target configuration were unimportant. Displacement of a colinear line over the same range without an offset evoked little, if any, response. In the second study, EPs were recorded in response to a single offset target which varied in magnitude from 21 to 82 sec of visual angle on different trials. The latency and amplitude of the EP response varied systematically with the amplitude of the vernier offset. Plots of EP amplitude against log of the offset magnitude were linear over the range of offsets employed. Straight lines fitted to the data and extrapolated to zero amplitude provided estimates of vernier threshold. These estimates agreed closely with psychophysical measures taken with the same targets and confirm the initial observations by Levi et al. (1983). In the third experiment, irrelevant contours were added to the vernier target in various spatial and temporal configurations. The addition of stationary, contiguous contours to the vernier target reduced the amplitude of the EP response when the contours were within 4-8 min of the offset, producing progressively less EP attenuation with increasing distance from the offset. However, brief presentation of the irrelevant contour (e.g. a single line passing through the offset) with an onset asynchrony relative to the vernier offset stimulus appropriate to assure simultaneity of the line-elicited EP and the offset-elicited EP yielded an enhanced response, i.e. to two responses added algebraically. The long latency of the offset evoked response and the summation results of the EPs generated by an offset and by a briefly presented linear contour suggests independence of the neural generators producing the response to these two targets.
在三个实验中，对产生针对游标偏移短暂呈现的诱发电位的神经发生器的特征进行了研究。在第一项研究中，将响应于单个游标偏移刺激记录的平均诱发电位（EPs）进行了比较，该刺激由一条水平线组成，每1.5秒有100毫秒从共线性变为非共线性，与由其他游标配置引发的反应进行比较，这些配置包括：具有多个偏移的刺激；以不同方向呈现的刺激；具有不同偏移特征的目标；以及共线直线的简单位移。结果表明，如果偏移位于目标的中心区域（1度），单个游标偏移会引发强烈的反应。目标配置的其他特征并不重要。在没有偏移的情况下，共线直线在相同范围内的位移几乎不会引发反应（如果有反应的话）。在第二项研究中，记录了对单个偏移目标的EPs，该目标在不同试验中视角大小从21秒到82秒不等。EP反应的潜伏期和振幅随游标偏移的幅度系统地变化。在所用偏移范围内，EP振幅相对于偏移量对数的图呈线性。拟合数据并外推到零振幅的直线提供了游标阈值的估计。这些估计与使用相同目标进行的心理物理学测量结果非常一致，并证实了Levi等人（1983年）的初步观察结果。在第三个实验中，以各种空间和时间配置向游标目标添加了无关轮廓。当轮廓在偏移的4 - 8分钟内时，向游标目标添加静止、相邻的轮廓会降低EP反应的振幅，随着与偏移距离的增加，产生的EP衰减逐渐减少。然而，相对于游标偏移刺激以适当的起始异步呈现无关轮廓（例如，一条穿过偏移的单线），以确保由线引发的EP和由偏移引发的EP同时出现，会产生增强的反应，即两个反应代数相加。偏移诱发反应的长潜伏期以及由偏移和短暂呈现的线性轮廓产生的EPs的总和结果表明，产生对这两个目标反应的神经发生器是独立的。
