Vassilev A, Zlatkova M, Mitova L
Institute of Physiology, Bulgarian Academy of Sciences, Sofia.
Exp Brain Res. 1989;74(2):421-6. doi: 10.1007/BF00248877.
The effect of background intensity on the spatial summation of rectangular stimuli of varying length and width was studied in human psychophysical experiments and compared with the known effects of light adaptation on the spatial summation of circular stimuli. Both the detection threshold and the threshold of orientation identification were measured. In agreement with previous data, summation was more efficient along the line stimulus than across it. This asymmetry was found to exist at all adaptation levels studied (1-1000 trolands). The adaptation level affected both length and width summation; the change in the length of summation was twice as great as the change in the diameter of summation with circular stimuli. Orientation selectivity was reduced for short lines presented on a dim background. The results suggest the existence of mechanisms of light adaptation at the level of cortical orientation-selective units.
在人体心理物理学实验中，研究了背景强度对不同长度和宽度的矩形刺激空间总和的影响，并与光适应对圆形刺激空间总和的已知影响进行了比较。测量了检测阈值和方向识别阈值。与先前的数据一致，沿直线刺激的总和比跨直线刺激更有效。发现在所有研究的适应水平（1 - 1000托兰）下都存在这种不对称性。适应水平影响长度和宽度总和；直线刺激总和长度的变化是圆形刺激总和直径变化的两倍。在昏暗背景下呈现的短线的方向选择性降低。结果表明在皮质方向选择性单元水平存在光适应机制。
