The LINE (Laboratory for Investigative Neurophysiology), Department of Radiology and Department of Clinical Neurosciences, University Hospital Center and University of Lausanne, Lausanne, Switzerland.
The LINE (Laboratory for Investigative Neurophysiology), Department of Radiology and Department of Clinical Neurosciences, University Hospital Center and University of Lausanne, Lausanne, Switzerland; Department of Ophthalmology, University of Lausanne, Fondation Asile des Aveugles, Lausanne, Switzerland.
Neuroimage. 2018 Nov 1;181:182-189. doi: 10.1016/j.neuroimage.2018.07.017. Epub 2018 Jul 7.
Illusory contours (ICs) are perceptions of visual borders despite absent contrast gradients. The psychophysical and neurobiological mechanisms of IC processes have been studied across species and diverse brain imaging/mapping techniques. Nonetheless, debate continues regarding whether IC sensitivity results from a (presumably) feedforward process within low-level visual cortices (V1/V2) or instead are processed first within higher-order brain regions, such as lateral occipital cortices (LOC). Studies in animal models, which generally favour a feedforward mechanism within V1/V2, have typically involved stimuli inducing IC lines. By contrast, studies in humans generally favour a mechanism where IC sensitivity is mediated by LOC and have typically involved stimuli inducing IC forms or shapes. Thus, the particular stimulus features used may strongly contribute to the model of IC sensitivity supported. To address this, we recorded visual evoked potentials (VEPs) while presenting human observers with an array of 10 inducers within the central 5°, two of which could be oriented to induce an IC line on a given trial. VEPs were analysed using an electrical neuroimaging framework. Sensitivity to the presence vs. absence of centrally-presented IC lines was first apparent at ∼200 ms post-stimulus onset and was evident as topographic differences across conditions. We also localized these differences to the LOC. The timing and localization of these effects are consistent with a model of IC sensitivity commencing within higher-level visual cortices. We propose that prior observations of effects within lower-tier cortices (V1/V2) are the result of feedback from IC sensitivity that originates instead within higher-tier cortices (LOC).
错觉轮廓 (ICs) 是指在没有对比梯度的情况下感知到的视觉边界。跨物种和各种脑成像/映射技术研究了 IC 过程的心理物理学和神经生物学机制。尽管如此，关于 IC 敏感性是源自低水平视觉皮层 (V1/V2) 中的（大概）前馈过程，还是首先在外侧枕叶皮层 (LOC) 等高级脑区中处理，仍存在争议。动物模型的研究通常倾向于 V1/V2 中的前馈机制，这些研究通常涉及诱导 IC 线的刺激。相比之下，人类的研究通常倾向于 LOC 介导的 IC 敏感性机制，并且通常涉及诱导 IC 形式或形状的刺激。因此，所使用的特定刺激特征可能会强烈影响支持的 IC 敏感性模型。为了解决这个问题，我们在向人类观察者呈现中央 5°内的 10 个诱导器阵列时记录了视觉诱发电位 (VEPs)，其中两个可以定向以在给定试验中诱导 IC 线。使用电神经影像学框架分析 VEPs。对中央呈现的 IC 线的存在与不存在的敏感性首先在刺激后约 200 毫秒时出现，并且在条件之间的地形差异中显而易见。我们还将这些差异定位到 LOC。这些效应的时间和定位与 IC 敏感性起始于高级视觉皮层的模型一致。我们提出，先前在较低层次皮层 (V1/V2) 中观察到的效应是源自起源于较高层次皮层 (LOC) 的 IC 敏感性的反馈的结果。
