Cross-fixation interactions of orientations suggest that orientation decoding occurs in a high-level area of visual working memory
Cross-fixation interactions of orientations suggest that orientation decoding occurs in a high-level area of visual working memory
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DOI：
10.1167/jov.20.11.216
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发表时间：
2020-10
影响因子：
1.8
通讯作者：
Long Luu;Mingsha Zhang;M. Tsodyks;N. Qian
中科院分区：
文献类型：
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作者：
Long Luu;Mingsha Zhang;M. Tsodyks;N. Qian
视觉编码（刺激如何引起神经元反应）是已知的进展，从低到高水平。相比之下，解码（反应如何导致感知）则鲜为人知，但人们普遍认为它遵循相同的从低到高的层次结构。根据这一假设，方向解码必须发生在低级别区域，如V1，因此，在固定的相对侧的两个方向不应该相互作用的感知。然而，Ding et al（PNAS，2017）提供了反对这一假设的证据，并提出视觉解码可能遵循相反的工作记忆中的高到低层次结构。如果注视点两侧的两个方向都与任务相关，并在延迟期内进入高级工作记忆区，那么它们应该相互作用。我们测试了这个预测。当两条方向差为5的线在注视点的相对两侧闪现时，被试保持中心注视，中心到中心的距离为16个视角。他们的眼睛位置进行了监测与红外线眼动仪和试验中断固定中止。延迟一段时间后，受试者通过在注视处绘制和调整指示线来报告两个方向。在一种情况下，指示线在第一次报告后消失，并在第二次报告中重新绘制，以尽量减少潜在的干扰。我们发现，这两条线之间表现出巨大而显著的排斥，证明了工作记忆中预测的交叉注视相互作用。该模式在14名受试者中一致。对照条件和分析排除了其他解释，如固定同侧试验间的相互作用。此外，我们定量地解释了排斥与回顾贝叶斯解码模型在丁等。我们的结论是，我们的研究结果支持的理论，视知觉可能被视为高到低级别的解码工作记忆。
Visual encoding (how stimuli evoke neuronal responses) is known to progress from low to high levels. Decoding (how responses lead to perception), in contrast, is less understood but is widely assumed to follow the same, low-to-high-level hierarchy. According to this assumption, orientation decoding must occur in low-level areas such as V1, and consequently, two orientations on opposite sides of the fixation should not interact with each other perceptually. However, Ding et al (PNAS, 2017) provided evidence against the assumption and proposed that visual decoding may follow the opposite, high-to-low-level hierarchy in working memory. If two orientations on opposite sides of the fixation are both task relevant and enter a high-level working-memory area in a delay period, then they should interact with each other. We tested this prediction. Subjects maintained central fixation when two lines with an orientation difference of 5 were flashed on opposite sides of the fixation, with a center-to-center distance of 16 of visual angle. Their eye positions were monitored with an infrared eye tracker and trials with broken fixation were aborted. After a delay, subjects reported the two orientations by drawing and adjusting an indicator line at the fixation. In one condition, the indicator line disappeared after the first report, and was redrawn for the second report, to minimize potential interference. We found that the two lines showed a large and significant repulsion between them, demonstrating the predicted cross-fixation interactions in working memory. The pattern was consistent across 14 subjects. Control conditions and analyses ruled out alternative explanations such as interactions across trials on the same side of the fixation. Moreover, we quantitatively accounted for the repulsion with the retrospective Bayesian decoding model in Ding et al. We conclude that our results support the theory that visual perception may be viewed as high-to-low-level decoding in working memory.