Dowling J E
Science. 1967 Jan 20;155(3760):273-9. doi: 10.1126/science.155.3760.273.
In response to background illumination, the adaptation properties of the b-wave are similar to those observed in the human eye with psychophysical methods. With increasing background luminance the b-wave sensitivity is diminished; except at the lowest background intensity the elevation of the log threshold is linearly related to the increase of background intensity, the relation having a slope of almost 1. The a-wave, however, behaves quite differently. At low background luminances it shows little adaptation. With higher background luminances the awave saturates, and no a-wave potential can be elicited with any stimulus intensity. The L-type S-potentials respond to background light in much the same way as the a-wave does. Thus, the b-wave is the first of the known responses in the visual system to show typical adaptation properties. This suggests that the site of visual adaptation may be in the bi-polarcell layer, the presumed locus of b-wave generation. Recent electron microscopic studies have demonstrated reciprocal synapses between the bipolar terminals and amacrine processes, and it is suggested that such a synaptic arrangement could account for visual adaptation by a mechanism of inhibitory feedback on the bipolar cells.
作为对背景光照的响应，b波的适应特性与用心理物理学方法在人眼中观察到的相似。随着背景亮度增加，b波敏感性降低；除了在最低背景强度下，对数阈值的升高与背景强度的增加呈线性相关，该关系的斜率几乎为1。然而，a波的表现则大不相同。在低背景亮度下，它几乎没有适应性。随着背景亮度升高，a波饱和，任何刺激强度都无法引出a波电位。L型S电位对背景光的反应与a波大致相同。因此，b波是视觉系统中已知的首个表现出典型适应特性的反应。这表明视觉适应的位点可能在双极细胞层，即推测的b波产生位点。最近的电子显微镜研究已经证明双极终末与无长突细胞突起之间存在相互突触，有人认为这种突触排列可以通过对双极细胞的抑制性反馈机制来解释视觉适应。
