Goal-Directed Visual Processing Differentially Impacts Human Ventral and Dorsal Visual Representations
Goal-Directed Visual Processing Differentially Impacts Human Ventral and Dorsal Visual Representations
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DOI：
10.1523/jneurosci.3392-16.2017
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发表时间：
2017-09-06
影响因子：
5.3
通讯作者：
Xu, Yaoda
中科院分区：
文献类型：
--
作者：
Vaziri-Pashkam, Maryam;Xu, Yaoda
最近的研究对腹侧/“什么”和背侧/“哪里”两条视觉加工路径的观点提出了挑战，表明这两条路径中都存在“什么”和“哪里”信息。两条道路的区别仍然有效吗？在这里，我们研究了目标导向的视觉信息处理如何在这两条路径上对视觉表征产生不同的影响。使用功能磁共振成像和多变量模式分析，在三个实验中，通过操纵颜色或形状是否与任务相关，以及它们是如何连接的，我们在枕颞区和顶区考察了基于形状的物体类别解码。我们发现，所有被考察的区域中的物体类别表征都受到物体形状是否与任务相关的影响。然而，随着与任务相关和无关的特征更多地被整合，这种任务效应趋于减弱，这反映了众所周知的基于对象的特征编码。有趣的是，任务关联性在驱动早期视觉和腹侧客体区域的表征结构中起到的作用相对较小。它们主要是由物体形状的变化驱动的。相反，背侧区域的任务效应远大于腹侧区域，客体类别和任务关联性对背侧区域的表征结构都有显著贡献。这些结果表明，虽然腹侧通路的视觉表征更具不变性，并反映了“一个物体是什么”，但背侧通路的视觉表征更具适应性，反映了“我们如何处理它”。因此，尽管在两条视觉加工路径中都存在“什么”和“在哪里”信息，但这两条路径在视觉信息表征中的作用可能仍然是根本不同的。
Recent studies have challenged the ventral/"what" and dorsal/"where" two-visual-processing-pathway view by showing the existence of "what" and "where" information in both pathways. Is the two-pathway distinction still valid? Here, we examined how goal-directed visual information processing may differentially impact visual representations in these two pathways. Using fMRI and multivariate pattern analysis, in three experiments on human participants (57% females), by manipulating whether color or shape was task-relevant and how they were conjoined, we examined shape-based object category decoding in occipitotemporal and parietal regions. We found that object category representations in all the regions examined were influenced by whether or not object shape was task-relevant. This task effect, however, tended to decrease as task-relevant and irrelevant features were more integrated, reflecting the well-known object-based feature encoding. Interestingly, task relevance played a relatively minor role in driving the representational structures of early visual and ventral object regions. They were driven predominantly by variations in object shapes. In contrast, the effect of task was much greater in dorsal than ventral regions, with object category and task relevance both contributing significantly to the representational structures of the dorsal regions. These results showed that, whereas visual representations in the ventral pathway are more invariant and reflect "what an object is, "those in the dorsal pathway are more adaptive and reflect "what we do with it." Thus, despite the existence of "what" and "where" information in both visual processing pathways, the two pathways may still differ fundamentally in their roles in visual information representation.