通过人类功能磁共振成像和脑磁图解码揭示场景与物体加工之间的相互作用

Interaction between Scene and Object Processing Revealed by Human fMRI and MEG Decoding.

作者信息

Brandman Talia, Peelen Marius V

机构信息

Center for Mind/Brain Sciences, University of Trento, 38068 Rovereto (TN), Italy

Center for Mind/Brain Sciences, University of Trento, 38068 Rovereto (TN), Italy.

出版信息

J Neurosci. 2017 Aug 9;37(32):7700-7710. doi: 10.1523/JNEUROSCI.0582-17.2017. Epub 2017 Jul 7.

Abstract

Scenes strongly facilitate object recognition, such as when we make out the shape of a distant boat on the water. Yet, although known to interact in perception, neuroimaging research has primarily provided evidence for separate scene- and object-selective cortical pathways. This raises the question of how these pathways interact to support context-based perception. Here we used a novel approach in human fMRI and MEG studies to reveal supra-additive scene-object interactions. Participants (men and women) viewed degraded objects that were hard to recognize when presented in isolation but easy to recognize within their original scene context, in which no other associated objects were present. fMRI decoding showed that the multivariate representation of the objects' category (animate/inanimate) in object-selective cortex was strongly enhanced by the presence of scene context, even though the scenes alone did not evoke category-selective response patterns. This effect in object-selective cortex was correlated with concurrent activity in scene-selective regions. MEG decoding results revealed that scene-based facilitation of object processing peaked at 320 ms after stimulus onset, 100 ms later than peak decoding of intact objects. Together, results suggest that expectations derived from scene information, processed in scene-selective cortex, feed back to shape object representations in visual cortex. These findings characterize, in space and time, functional interactions between scene- and object-processing pathways. Although scenes and objects are known to contextually interact in visual perception, the study of high-level vision has mostly focused on the dissociation between their selective neural pathways. The current findings are the first to reveal direct facilitation of object recognition and neural representation by scene background, even in the absence of contextually associated objects. Using a multivariate approach to both fMRI and MEG, we characterize the functional neuroanatomy and neural dynamics of such scene-based object facilitation. Finally, the correlation of this effect with scene-selective activity suggests that, although functionally distinct, scene and object processing pathways do interact at a perceptual level to fill in for insufficient visual detail.

摘要

场景能极大地促进物体识别,比如当我们辨认出水面上一艘远处船只的形状时。然而,尽管已知场景和物体在感知过程中相互作用,但神经影像学研究主要提供了证据,证明存在独立的场景选择性和物体选择性皮质通路。这就引发了一个问题:这些通路如何相互作用以支持基于情境的感知。在这里,我们在人类功能磁共振成像(fMRI)和脑磁图(MEG)研究中采用了一种新方法,以揭示超相加性的场景 - 物体相互作用。参与者(男性和女性)观看了一些退化的物体,这些物体单独呈现时很难辨认,但在其原始场景背景中(其中不存在其他相关物体)却很容易辨认。fMRI解码显示,即使单独的场景不会引发类别选择性反应模式,但场景背景的存在会强烈增强物体选择性皮质中物体类别的多变量表征(有生命/无生命)。物体选择性皮质中的这种效应与场景选择性区域的同步活动相关。MEG解码结果表明,基于场景的物体处理促进作用在刺激开始后320毫秒达到峰值,比完整物体的峰值解码晚100毫秒。综合来看,结果表明在场景选择性皮质中处理的来自场景信息的期望会反馈回来,塑造视觉皮质中的物体表征。这些发现在空间和时间上表征了场景处理和物体处理通路之间的功能相互作用。尽管已知场景和物体在视觉感知中会在情境中相互作用,但高级视觉研究大多集中在它们选择性神经通路之间的分离上。目前的发现首次揭示了即使在没有情境相关物体的情况下,场景背景对物体识别和神经表征的直接促进作用。通过对fMRI和MEG都采用多变量方法,我们表征了这种基于场景的物体促进作用的功能神经解剖学和神经动力学。最后,这种效应与场景选择性活动的相关性表明,尽管功能不同,但场景和物体处理通路在感知层面确实相互作用,以弥补视觉细节的不足。

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