Zago Laure, Petit Laurent, Turbelin Marie-Renée, Andersson Frédéric, Vigneau Mathieu, Tzourio-Mazoyer Nathalie
CI-NAPS UMR 6232, CNRS, CEA, Université Caen Basse Normandie, Université Paris Descartes, France.
Neuropsychologia. 2008;46(9):2403-14. doi: 10.1016/j.neuropsychologia.2008.03.001. Epub 2008 Mar 18.
The manipulation of numbers required during calculation is known to rely on working memory (WM) resources. Here, we investigated the respective contributions of verbal and/or spatial WM manipulation brain networks during the addition of four numbers performed by adults, using functional magnetic resonance imaging (fMRI). Both manipulation and maintenance tasks were proposed with syllables, locations, or two-digit numbers. As compared to their maintenance, numbers manipulation (addition) elicited increased activation within a widespread cortical network including inferior temporal, parietal, and prefrontal regions. Our results demonstrate that mastery of arithmetic calculation requires the cooperation of three WM manipulation systems: an executive manipulation system conjointly recruited by the three manipulation tasks, including the anterior cingulate cortex (ACC), the orbital part of the inferior frontal gyrus, and the caudate nuclei; a left-lateralized, language-related, inferior fronto-temporal system elicited by numbers and syllables manipulation tasks required for retrieval, selection, and association of symbolic information; and a right superior and posterior fronto-parietal system elicited by numbers and locations manipulation tasks for spatial WM and attentional processes. Our results provide new information that the anterior intraparietal sulcus (IPS) is involved in tasks requiring a magnitude processing with symbolic (numbers) and nonsymbolic (locations) stimuli. Furthermore, the specificity of arithmetic processing is mediated by a left-hemispheric specialization of the anterior and posterior parts of the IPS as compared to a spatial task involving magnitude processing with nonsymbolic material.
计算过程中所需的数字运算依赖于工作记忆（WM）资源。在此，我们使用功能磁共振成像（fMRI），研究了成年人在进行四个数字相加时，言语和/或空间WM运算脑网络各自的作用。运算和保持任务分别采用音节、位置或两位数来进行。与保持任务相比，数字运算（加法）在包括颞下回、顶叶和前额叶区域在内的广泛皮质网络中引起了更强的激活。我们的结果表明，算术计算的掌握需要三个WM运算系统的协作：一个由三个运算任务共同招募的执行运算系统，包括前扣带回皮质（ACC）、额下回眶部和尾状核；一个由数字和音节运算任务引发的、与语言相关的左侧额颞下系统，用于检索、选择和关联符号信息；以及一个由数字和位置运算任务引发的右上后额顶系统，用于空间WM和注意力过程。我们的结果提供了新的信息，即顶内沟前部（IPS）参与了需要对符号（数字）和非符号（位置）刺激进行数量处理的任务。此外，与涉及对非符号材料进行数量处理的空间任务相比，算术处理的特异性由IPS前后部的左半球特化介导。
