Tanaka Satoshi, Seki Keiko, Hanakawa Takashi, Harada Madoka, Sugawara Sho K, Sadato Norihiro, Watanabe Katsumi, Honda Manabu
Center for Fostering Young and Innovative Researchers, Nagoya Institute of Technology Nagoya, Japan.
Front Psychol. 2012 Aug 28;3:315. doi: 10.3389/fpsyg.2012.00315. eCollection 2012.
The abacus, a traditional physical calculation device, is still widely used in Asian countries. Previous behavioral work has shown that skilled abacus users perform rapid and precise mental arithmetic by manipulating a mental representation of an abacus, which is based on visual imagery. However, its neurophysiological basis remains unclear. Here, we report the case of a patient who was a good abacus user, but transiently lost her "mental abacus" and superior arithmetic performance after a stroke owing to a right hemispheric lesion including the dorsal premotor cortex (PMd) and inferior parietal lobule (IPL). Functional magnetic resonance imaging experiments were conducted 6 and 13 months after her stroke. In the mental calculation task, her brain activity was shifted from the language-related areas, including Broca's area and the left dorsolateral prefrontal and IPLs, to the visuospatial-related brain areas including the left superior parietal lobule (SPL), according to the recovery of her arithmetic abilities. In the digit memory task, activities in the bilateral SPL, and right visual association cortex were also observed after recovery. The shift of brain activities was consistent with her subjective report that she was able to shift the calculation strategy from linguistic to visuospatial as her mental abacus became stable again. In a behavioral experiment using an interference paradigm, a visual presentation of an abacus picture, but not a human face picture, interfered with the performance of her digit memory, confirming her use of the mental abacus after recovery. This is the first case report on the impairment of the mental abacus by a brain lesion and on recovery-related brain activity. We named this rare case "abacus-based acalculia." Together with previous neuroimaging studies, the present result suggests an important role for the PMd and parietal cortex in the superior arithmetic ability of abacus users.
算盘，一种传统的实物计算工具，在亚洲国家仍被广泛使用。先前的行为学研究表明，熟练的算盘使用者通过操纵基于视觉意象的算盘心理表征来进行快速而精确的心算。然而，其神经生理基础仍不清楚。在此，我们报告一例患者，她是一位熟练的算盘使用者，但在中风后，由于右侧半球包括背侧运动前区（PMd）和顶下小叶（IPL）的病变，暂时失去了她的“心理算盘”和卓越的算术能力。在她中风后的6个月和13个月进行了功能磁共振成像实验。在心算任务中，根据她算术能力的恢复情况，她的大脑活动从包括布洛卡区、左侧背外侧前额叶和顶下小叶在内的语言相关区域，转移到了包括左侧顶上小叶（SPL）在内的视觉空间相关脑区。在数字记忆任务中，恢复后双侧顶上小叶和右侧视觉联合皮层也观察到了活动。大脑活动的转移与她的主观报告一致，即随着她的心理算盘再次稳定，她能够将计算策略从语言策略转变为视觉空间策略。在一项使用干扰范式的行为实验中，算盘图片的视觉呈现，而不是人脸图片，干扰了她的数字记忆表现，证实了她恢复后对心理算盘的使用。这是第一例关于脑损伤导致心理算盘受损以及与恢复相关的脑活动的病例报告。我们将这个罕见病例命名为“基于算盘的失算症”。与先前的神经影像学研究一起，目前的结果表明PMd和顶叶皮层在算盘使用者卓越的算术能力中起着重要作用。
