Fresnoza Shane, Christova Monica, Purgstaller Sieglinde, Jehna Margit, Zaar Karla, Hoffermann Markus, Mahdy Ali Kariem, Körner Christof, Gallasch Eugen, von Campe Gord, Ischebeck Anja
Institute of Psychology, University of Graz, Graz, Austria.
BioTechMed, Graz, Austria.
Front Hum Neurosci. 2020 Jul 16;14:271. doi: 10.3389/fnhum.2020.00271. eCollection 2020.
The triple-code model (TCM) of number processing suggests the involvement of distinct parietal cortex areas in arithmetic operations: the bilateral horizontal segment of the intraparietal sulcus (hIPS) for arithmetic operations that require the manipulation of numerical quantities (e.g., subtraction) and the left angular gyrus (AG) for arithmetic operations that require the retrieval of answers from long-term memory (e.g., multiplication). Although neuropsychological, neuroimaging, and brain stimulation studies suggest the dissociation of these operations into distinct parietal cortex areas, the role of strategy (online calculation vs. retrieval) is not yet fully established. In the present study, we further explored the causal involvement of the left AG for multiplication and left hIPS for subtraction using a neuronavigated repetitive transcranial magnetic stimulation (rTMS) paradigm. Stimulation sites were determined based on an fMRI experiment using the same tasks. To account for the effect of strategy, participants were asked whether they used retrieval or calculation for each individual problem. We predicted that the stimulation of the left AG would selectively disrupt the retrieval of the solution to multiplication problems. On the other hand, stimulation of the left hIPS should selectively disrupt subtraction. Our results revealed that left AG stimulation was detrimental to the retrieval and online calculation of solutions for multiplication problems, as well as, the retrieval (but not online calculation) of the solutions to subtraction problems. In contrast, left hIPS stimulation had no detrimental effect on both operations regardless of strategy.
数字处理的三重编码模型（TCM）表明，顶叶皮质的不同区域参与算术运算：双侧顶内沟水平段（hIPS）参与需要对数值进行操作的算术运算（如减法），而左侧角回（AG）参与需要从长期记忆中检索答案的算术运算（如乘法）。尽管神经心理学、神经影像学和脑刺激研究表明这些运算在顶叶皮质的不同区域是分离的，但策略（在线计算与检索）的作用尚未完全明确。在本研究中，我们使用神经导航重复经颅磁刺激（rTMS）范式，进一步探究了左侧AG对乘法运算和左侧hIPS对减法运算的因果关系。刺激部位是根据使用相同任务的功能磁共振成像（fMRI）实验确定的。为了考虑策略的影响，我们询问参与者针对每个具体问题是使用检索还是计算。我们预测，刺激左侧AG会选择性地干扰乘法问题答案的检索。另一方面，刺激左侧hIPS应该会选择性地干扰减法运算。我们的结果显示，刺激左侧AG对乘法问题答案的检索和在线计算均有不利影响，对减法问题答案的检索（而非在线计算）也有不利影响。相比之下，无论采用何种策略，刺激左侧hIPS对这两种运算均无不利影响。
