A Generic Mechanism for Perceptual Organization in the Parietal Cortex
A Generic Mechanism for Perceptual Organization in the Parietal Cortex
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DOI：
10.1523/jneurosci.0436-18.2018
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发表时间：
2018-08-08
影响因子：
5.3
通讯作者：
Bartels, Andreas
中科院分区：
文献类型：
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作者：
Grassi, Pablo R.;Zaretskaya, Natalia;Bartels, Andreas
我们的视觉系统将视觉元素分组为有意义的实体并将它们与其他实体分开的能力被称为场景分割。视觉运动通常为这一过程提供了有力的线索，因为视差或相干性可以告知视觉系统有关场景或物体结构的信息。在这里，我们测试的假设，场景分割的运动线索依赖于一个共同的神经基板顶叶皮层。我们使用功能磁共振成像和一组三个完全不同的运动刺激，以检查场景分割在人脑中。刺激涵盖了广泛的高层次的过程，包括知觉分组，透明运动，深度知觉。所有的刺激都是感知性的，使得感知每隔几秒钟交替一次，而物理刺激保持不变。知觉状态是不对称的，其中一个反映了默认（非分段）解释，另一个反映了非默认（分段）解释。我们证实了行为刺激呈现时，默认的接受总是被认为是第一，知觉交替之前。成像结果表明，在所有的刺激类感知场景分割与后顶叶皮层的活动增加，以及在早期视觉皮层的神经信号减少。这种激活模式与视觉感知的预测编码模型是兼容的，并表明顶叶皮层拥有一个通用的场景分割机制。
Our visual system's ability to group visual elements into meaningful entities and to separate them from others is referred to as scene segmentation. Visual motion often provides a powerful cue for this process as parallax or coherence can inform the visual system about scene or object structure. Here we tested the hypothesis that scene segmentation by motion cues relies on a common neural substrate in the parietal cortex. We used fMRI and a set of three entirely distinct motion stimuli to examine scene segmentation in the human brain. The stimuli covered a wide range of high-level processes, including perceptual grouping, transparent motion, and depth perception. All stimuli were perceptually bistable such that percepts alternated every few seconds while the physical stimulation remained constant. The perceptual states were asymmetric, in that one reflected the default (nonsegmented) interpretation, and the other the non-default (segmented) interpretation. We confirmed behaviorally that upon stimulus presentation, the default percept was always perceived first, before perceptual alternations ensued. Imaging results showed that across all stimulus classes perceptual scene-segmentation was associated with an increase of activity in the posterior parietal cortex together with a decrease of neural signal in the early visual cortex. This pattern of activation is compatible with predictive coding models of visual perception, and suggests that parietal cortex hosts a generic mechanism for scene segmentation.