Institute of Psychology, RWTH Aachen University, Aachen, Germany.
Hum Brain Mapp. 2011 Jan;32(1):51-9. doi: 10.1002/hbm.21002.
The goal of the present study was to investigate the neuroanatomical basis of arithmetic fact retrieval. The rationale was that areas playing a crucial role in arithmetic fact retrieval should show a systematic increase of activation with increasing retrieval effort. To achieve this goal, we utilized the problem-size effect as this is known to be systematically related to retrieval effort. In contrast to many previous studies, we here took a parametric approach to account for the continuous increase of retrieval effort with problem size. BOLD signals were modeled with problem size as parametric regressor and negative slow waves of the EEG were categorized into six levels of problem size. The fMRI data showed that activation in the angular gyrus and ACC/SMA increased parametrically with problem size. The ERP data showed a systematic amplitude increase with increasing problem size, especially at fronto-central electrodes. Consistent with the fMRI data, source modeling localized this effect to the ACC. While these findings support previous notions about the crucial role of the angular gyrus during fact retrieval, they also provide evidence that the medial frontal cortex is involved when single-digit multiplications are solved. Thus, both parietal and frontal structures seem to be integral parts of a system that enables and controls arithmetic fact retrieval.
本研究旨在探究算术事实检索的神经解剖学基础。其基本原理是，在算术事实检索中起关键作用的区域，其激活程度应随检索难度的增加而系统地增加。为了实现这一目标，我们利用问题大小效应，因为众所周知，问题大小与检索难度存在系统的关系。与许多先前的研究不同，我们采用参数方法来解释问题大小与检索难度的连续增加。BOLD 信号以问题大小作为参数回归器进行建模，而 EEG 的负慢波被分为六个问题大小级别。fMRI 数据显示，角回和 ACC/SMA 的激活随问题大小呈参数性增加。ERP 数据显示，随着问题大小的增加，振幅呈系统增加，尤其是在前额中央电极。与 fMRI 数据一致，源建模将此效应定位到 ACC。这些发现支持了先前关于角回在事实检索中起关键作用的观点，同时也为内侧额皮质在解决个位数乘法时参与提供了证据。因此，顶叶和额叶结构似乎都是允许和控制算术事实检索的系统的组成部分。
