Department of Communication Sciences and Disorders, Northwestern University, Evanston, Illinois, USA.
Hum Brain Mapp. 2011 Nov;32(11):1932-47. doi: 10.1002/hbm.21159. Epub 2011 Jan 18.
It has been proposed that recent cultural inventions such as symbolic arithmetic recycle evolutionary older neural mechanisms. A central assumption of this hypothesis is that the degree to which a preexisting mechanism is recycled depends on the degree of similarity between its initial function and the novel task. To test this assumption, we investigated whether the brain region involved in magnitude comparison in the intraparietal sulcus (IPS), localized by a numerosity comparison task, is recruited to a greater degree by arithmetic problems that involve number comparison (single-digit subtractions) than by problems that involve retrieving number facts from memory (single-digit multiplications). Our results confirmed that subtractions are associated with greater activity in the IPS than multiplications, whereas multiplications elicit greater activity than subtractions in regions involved in verbal processing including the middle temporal gyrus (MTG) and inferior frontal gyrus (IFG) that were localized by a phonological processing task. Pattern analyses further indicated that the neural mechanisms more active for subtraction than multiplication in the IPS overlap with those involved in numerosity comparison and that the strength of this overlap predicts interindividual performance in the subtraction task. These findings provide novel evidence that elementary arithmetic relies on the cooption of evolutionary older neural circuits.
有人提出,最近的文化发明,如符号算术,循环利用了进化早期的神经机制。这一假说的一个核心假设是,一个预先存在的机制被回收的程度取决于其初始功能与新任务之间的相似程度。为了检验这一假设,我们研究了在顶内沟(IPS)中参与数量比较的大脑区域,是否会因涉及数量比较(个位数减法)的算术问题而比涉及从记忆中检索数字事实(个位数乘法)的问题而被更大程度地招募。我们的结果证实,减法与 IPS 中的更大活动相关,而乘法则比减法在包括颞中回(MTG)和下额前回(IFG)在内的参与语音处理的区域中产生更大的活动,这些区域是通过语音处理任务定位的。模式分析进一步表明,IPS 中减法比乘法更活跃的神经机制与数量比较所涉及的神经机制重叠,而这种重叠的强度预测了减法任务中个体间的表现。这些发现提供了新的证据,表明基本的算术依赖于对进化早期神经回路的共同利用。