CAS Key Laboratory of Behavioral Science, Institute of Psychology, Beijing 100101, P.R. China.
University of Chinese Academy of Sciences, Beijing 100101, P.R. China.
Sci Rep. 2017 Jan 23;7:41101. doi: 10.1038/srep41101.
Whether the retinal process alone or retinal and cortical processes jointly determine afterimage (AI) formation has long been debated. Based on the retinal rebound responses, recent work proposes that afterimage signals are exclusively generated in the retina, although later modified by cortical mechanisms. We tested this notion with the method of "indirect proof". Each eye was presented with a 2-by-2 checkerboard of horizontal and vertical grating patches. Each corresponding patch of the two checkerboards was perpendicular to each other, which produces binocular rivalry, and can generate percepts ranging from complete interocular grouping to either monocular pattern. The monocular percepts became more frequent with higher contrast. Due to adaptation, the visual system is less sensitive during the AIs than during the inductions with AI-similar contrast. If the retina is the only origin of AIs, comparable contrast appearance would require stronger retinal signals in the AIs than in the inductions, thus leading to more frequent monocular percepts in the AIs than in the inductions. Surprisingly, subjects saw the fully coherent stripes significantly more often in AIs. Our results thus contradict the retinal generation notion, and suggest that in addition to the retina, cortex is directly involved in the generation of AI signals.
视网膜过程单独还是视网膜和皮层过程共同决定后像（AI）的形成，长期以来一直存在争议。基于视网膜反弹反应，最近的研究提出，尽管后来被皮层机制修改，但后像信号仅在视网膜中产生。我们使用“间接证明”的方法来检验这一观点。每只眼睛都呈现一个由水平和垂直光栅组成的 2x2 棋盘。两个棋盘的每个对应斑块彼此垂直，产生双眼竞争，并且可以产生从完全眼间分组到单个图案的感知。随着对比度的增加，单眼感知变得更加频繁。由于适应，视觉系统在 AI 期间比在具有 AI 相似对比度的诱导期间灵敏度更低。如果视网膜是 AI 的唯一起源，那么可比较的对比度出现需要在 AI 中比在诱导中更强的视网膜信号，从而导致 AI 中比在诱导中更频繁地出现单眼感知。令人惊讶的是，在 AI 中，受试者明显更频繁地看到完全一致的条纹。因此，我们的结果与视网膜产生的观点相矛盾，这表明除了视网膜之外，皮层也直接参与了 AI 信号的产生。
