Dissociating estimation from comparison and response eliminates parietal involvement in sequential numerosity perception
Dissociating estimation from comparison and response eliminates parietal involvement in sequential numerosity perception
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DOI：
10.1016/j.neuroimage.2015.04.019
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发表时间：
2015-08-01
期刊：
影响因子：
5.7
通讯作者：
Knops, Andre
中科院分区：
文献类型：
--
作者：
Cavdaroglu, Seda;Katz, Curren;Knops, Andre
顶叶皮层是否储存了一种抽象的数字表征，这种抽象的数字表征在阿拉伯数字和非符号刺激时都是以一种独立于感觉通道的方式被激活的，这一点一直受到广泛的争论。一些研究表明，时不变（同时）的符号和非符号视觉刺激中的数字信息在顶叶皮层中表示。在人类中，对于时变（顺序）刺激和来自不同模态的刺激是否激活相同的表征尚未确定。为了研究这个想法，我们测量了健康成年人的大脑激活，进行估计和/或比较顺序视觉（一系列的点）和听觉（一系列的哔哔声）数字。我们的实验设计使我们能够将数量估计与比较和响应相关因素分开。顶叶皮层的BOLD反应只有在参与者进行两个连续数字的比较时才增加。使用多变量模式分析，我们训练了一个分类器来解码各个感兴趣区域（ROI）中的数字。我们未能找到任何顶叶ROI，其中分类器可以在估计阶段解码的numerosities。相反，当参与者没有进行比较时，我们能够在听觉皮层ROI中解码听觉刺激的数字，在视觉皮层ROI中解码视觉刺激的数字。另一方面，在响应期间，分类器成功地解码了顶叶ROI中的视觉和听觉数字化的数字化信息。这些结果进一步证实了支持向量回归。总之，我们的研究不支持参与顶叶皮层在估计的顺序数在没有一个积极的任务与反应的要求。(C)2015 Elsevier Inc. All rights reserved.
It has been widely debated whether the parietal cortex stores an abstract representation of numerosity that is activated for Arabic digits as well as for non-symbolic stimuli in a sensory modality independent fashion. Some studies suggest that numerical information in time-invariant (simultaneous) symbolic and non-symbolic visual stimuli is represented in the parietal cortex. In humans, whether the same representation is activated for time-variant (sequential) stimuli and for stimuli coming from different modalities has not been determined. To investigate this idea, we measured the brain activation of healthy adults performing estimation and/or comparison of sequential visual (series of dots) and auditory (series of beeps) numerosities. Our experimental design allowed us to separate numerosity estimation from comparison and response related factors. The BOLD response in the parietal cortex increased only when participants were engaged in the comparison of two consecutive numerosities that required a response. Using multivariate pattern analysis we trained a classifier to decode numerosity in various regions of interest (ROI). We failed to find any parietal ROI where the classifier could decode numerosities during the estimation phase. Rather, when participants were not engaged in comparison we were able to decode numerosity in an auditory cortex ROI for auditory stimuli and in a visual cortex ROI for visual stimuli. On the other hand, during the response period the classifier successfully decoded numerosity information in a parietal ROI for both visual and auditory numerosities. These results were further confirmed by support vector regression. In sum, our study does not support the involvement of the parietal cortex during estimation of sequential numerosity in the absence of an active task with a response requirement. (C) 2015 Elsevier Inc. All rights reserved.