后顶叶皮层拓扑区域中注意依赖和空间特异性错觉形状反应的分离。

Dissociation between Attention-Dependent and Spatially Specific Illusory Shape Responses within the Topographic Areas of the Posterior Parietal Cortex.

机构信息

Department of Cognitive Psychology and Neuroscience, Institute of Psychology, University of Graz, 8010 Graz, Austria

BioTechMed-Graz, 8010 Graz, Austria.

出版信息

J Neurosci. 2022 Oct 26;42(43):8125-8135. doi: 10.1523/JNEUROSCI.0723-22.2022. Epub 2022 Sep 23.

Abstract

The human visual system consists of multiple topographic maps that extend from the early visual cortex (EVC) along the dorsal and ventral processing streams. Responses to illusory shapes within these maps have been demonstrated in the ventral stream areas, in particular the lateral occipital complex (LOC). Recently, the intraparietal sulcus (IPS) of the dorsal stream has been linked to the processing of illusory shapes defined by motion. It remains unclear whether the topographically organized parietal areas also respond to stationary illusory shapes, which would suggest their generic role in representing illusory content. In the current study we measured brain responses using fMRI while 30 human participants (12 male) observed flickering inducers around the fixation task. The inducers either formed an illusory diamond in the center, a triangle in the left or right hemifield, or were inverted such that no illusory figure was formed. We compared responses of parietal regions IPS0-IPS5 and SPL1 to each illusory figure with the nonillusory condition. To determine the role of attentional modulation on illusory shape responses we manipulated the difficulty of the fixation task. Our results show that all IPS areas responded to illusory shapes. The more posterior areas IPS0-IPS3 additionally displayed a preference toward contralateral shapes, while the more anterior areas IPS4 and IPS5 showed response attenuation with increased task difficulty. We suggest that the IPS can represent illusory content generated not only by moving, but also by stationary stimuli, and that there is a functional dissociation between attention-dependent anterior and spatially specific posterior topographic maps. The traditional view of the ventral visual pathway being solely responsible for representation of objects has recently been challenged by demonstrating illusory shape representation within the dorsal visual pathway with moving bistable stimuli. Our results provide evidence for the dorsal stream contribution to representing not only moving, but also stationary illusory shapes. Our results also show a functional subdivision along the topographic maps, with spatially specific shape responses in the more posterior, and attention-dependent responses in the more anterior areas. These findings have implications for our understanding of the relationship between attention and grouping in healthy individuals and neuropsychological patients. Furthermore, IPS areas should be considered in theoretical accounts and models of how subjective content is generated in the brain.

摘要

人类视觉系统由多个地形地图组成,这些地图从早期视觉皮层(EVC)沿着背侧和腹侧处理流延伸。在腹侧流区域,特别是外侧枕叶复合体(LOC),已经证明了对这些地图中幻觉形状的反应。最近,背侧流的顶内沟(IPS)已与由运动定义的幻觉形状的处理相关联。目前尚不清楚拓扑组织的顶叶区域是否也对静止的幻觉形状有反应,这表明它们在代表幻觉内容方面具有通用作用。在当前的研究中,我们使用 fMRI 测量了大脑反应,同时有 30 名参与者(12 名男性)观察了固定任务周围闪烁的诱导器。诱导器要么在中心形成一个虚幻的钻石,要么在左或右半视野中形成一个三角形,要么反转使得没有形成虚幻的图形。我们将 IPS0-IPS5 和 SPL1 对每个幻觉图形的反应与非幻觉条件进行了比较。为了确定注意力调节对幻觉形状反应的作用,我们操纵了固定任务的难度。我们的结果表明,所有 IPS 区域都对幻觉形状做出了反应。更靠后的 IPS0-IPS3 区域除了对对侧形状有偏好外,还显示出随着任务难度的增加,反应衰减。我们认为,IPS 不仅可以表示由运动产生的幻觉内容,还可以表示由静止刺激产生的幻觉内容,并且在注意力依赖的前和空间特定的后拓扑地图之间存在功能分离。传统的观点认为,腹侧视觉通路仅负责物体的表示,最近通过在背侧视觉通路上用移动双稳态刺激证明了幻觉形状的表示,这一观点受到了挑战。我们的结果为背侧流不仅对移动的,而且对静止的幻觉形状的表示提供了证据。我们的结果还显示了沿着地形地图的功能细分,更靠后的区域具有空间特定的形状反应,而更靠前的区域具有注意力依赖的反应。这些发现对我们理解健康个体和神经心理患者的注意力和分组之间的关系具有启示意义。此外,在理论上和模型中,应该考虑 IPS 区域如何在大脑中生成主观内容。

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