Ansari Daniel, Fugelsang Jonathan A, Dhital Bibek, Venkatraman Vinod
Numerical Cognition Laboratory, Department of Education, Dartmouth College, 3 Maynard Street, Raven House, Hanover, NH 03755, USA.
Neuroimage. 2006 Aug 15;32(2):799-805. doi: 10.1016/j.neuroimage.2006.04.184. Epub 2006 May 30.
Functional neuroimaging studies of numerical cognition have repeatedly associated activation of the intraparietal sulcus (IPS) with number processing. During number comparison, the IPS has been found to be modulated by the numerical distance. This has lead to the contention that the IPS houses the internal representation of numerical magnitude. However, this theory has been challenged by the argument that IPS activation may reflect domain-general response selection. In the present study, we used the numerical size congruity paradigm to further elucidate the role played by the IPS in number comparison. In an event-related, functional magnetic resonance imaging (fMRI) study, participants judged which of two number words was numerically larger. In addition to the numerical distance, physical stimulus size was varied such that physical size and numerical magnitude were either (a) congruent (e.g., numerically smaller number printed in smaller font) or (b) incongruent (e.g., numerically larger number printed in smaller font). This allowed for the study of both the main effects and the interaction of numerical distance and stimulus congruency. A main effect of numerical distance was found in bilateral regions of the IPS. However, these parietal areas were not significantly modulated by congruency or the interaction of distance and congruency. Instead, the main effect of congruency and an interaction of distance and congruency were observed in anterior cingulate and prefrontal cortices. These findings suggest some degree of independence between the processing of numerical distance and size congruity, lending support for the hypothesis that distance effects in IPS reflect the underlying representation of numerical magnitude.
数字认知的功能神经影像学研究反复表明，顶内沟（IPS）的激活与数字处理相关。在数字比较过程中，已发现IPS会受到数字距离的调节。这引发了一种观点，即IPS存储着数字大小的内部表征。然而，这一理论受到了质疑，有人认为IPS的激活可能反映的是领域通用的反应选择。在本研究中，我们使用数字大小一致性范式来进一步阐明IPS在数字比较中所起的作用。在一项事件相关的功能磁共振成像（fMRI）研究中，参与者判断两个数字词中哪个在数值上更大。除了数字距离外，物理刺激大小也有所变化，使得物理大小和数字大小要么（a）一致（例如，数值较小的数字用较小的字体打印），要么（b）不一致（例如，数值较大的数字用较小的字体打印）。这使得我们能够研究数字距离和刺激一致性的主效应以及它们之间的相互作用。在IPS的双侧区域发现了数字距离的主效应。然而，这些顶叶区域并未受到一致性或距离与一致性相互作用的显著调节。相反，在扣带回前部和前额叶皮层观察到了一致性的主效应以及距离与一致性的相互作用。这些发现表明，数字距离处理和大小一致性处理之间存在一定程度的独立性，这支持了IPS中的距离效应反映数字大小潜在表征的假设。
