两视系统假说：来自视觉失认症患者 DF 的新挑战和新见解。
The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF.
机构信息
Graduate Program in Neuroscience, The University of Western Ontario , London, ON , Canada ; Department of Psychology, The University of Western Ontario , London, ON , Canada ; Brain and Mind Institute, The University of Western Ontario , London, ON , Canada.
Department of Psychology, Durham University , Durham , UK.
出版信息
Front Neurol. 2014 Dec 8;5:255. doi: 10.3389/fneur.2014.00255. eCollection 2014.
Patient DF, who developed visual form agnosia following carbon monoxide poisoning, is still able to use vision to adjust the configuration of her grasping hand to the geometry of a goal object. This striking dissociation between perception and action in DF provided a key piece of evidence for the formulation of Goodale and Milner's Two Visual Systems Hypothesis (TVSH). According to the TVSH, the ventral stream plays a critical role in constructing our visual percepts, whereas the dorsal stream mediates the visual control of action, such as visually guided grasping. In this review, we discuss recent studies of DF that provide new insights into the functional organization of the dorsal and ventral streams. We confirm recent evidence that DF has dorsal as well as ventral brain damage - and that her dorsal-stream lesions and surrounding atrophy have increased in size since her first published brain scan. We argue that the damage to DF's dorsal stream explains her deficits in directing actions at targets in the periphery. We then focus on DF's ability to accurately adjust her in-flight hand aperture to changes in the width of goal objects (grip scaling) whose dimensions she cannot explicitly report. An examination of several studies of DF's grip scaling under natural conditions reveals a modest though significant deficit. Importantly, however, she continues to show a robust dissociation between form vision for perception and form vision-for-action. We also review recent studies that explore the role of online visual feedback and terminal haptic feedback in the programming and control of her grasping. These studies make it clear that DF is no more reliant on visual or haptic feedback than are neurologically intact individuals. In short, we argue that her ability to grasp objects depends on visual feedforward processing carried out by visuomotor networks in her dorsal stream that function in the much the same way as they do in neurologically intact individuals.
患者 DF 因一氧化碳中毒后出现视觉形态失认症，但仍能够利用视觉来调整抓握手的构型以适应目标物体的几何形状。DF 身上这种知觉与动作之间显著的分离现象为 Goodale 和 Milner 的双通道视觉系统假说（Two Visual Systems Hypothesis，TVSH）提供了关键性的证据。根据 TVSH，腹侧流在构建我们的视觉感知中起着至关重要的作用，而背侧流则介导视觉对动作的控制，例如视觉引导的抓握。在这篇综述中，我们讨论了最近对 DF 的研究，这些研究为背侧和腹侧流的功能组织提供了新的见解。我们证实了最近的证据，即 DF 既有背侧损伤也有腹侧损伤——并且自她的第一次脑部扫描以来，她的背侧流损伤及其周围萎缩的范围已经扩大。我们认为，DF 背侧流的损伤解释了她在指向周围目标时的动作缺陷。然后，我们将重点放在 DF 准确调整飞行中手孔以适应目标物体宽度（抓握缩放）的能力上，她无法明确报告目标物体的尺寸。对 DF 在自然条件下进行的抓握缩放的几项研究进行检查，结果发现了一种适度但显著的缺陷。然而，重要的是，她继续表现出感知和动作形式视觉之间的强大分离。我们还回顾了最近的一些研究，这些研究探索了在线视觉反馈和终端触觉反馈在她的抓握编程和控制中的作用。这些研究清楚地表明，DF 并不比神经健全的个体更依赖视觉或触觉反馈。简而言之，我们认为她抓握物体的能力取决于她背侧流中的运动视觉网络进行的视觉前馈处理，这些网络的功能与神经健全的个体非常相似。
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