Six-month abacus training improves working memory performance in children: a functional MRI and behavior study
Abstract
Abacus experts have demonstrated extraordinary potential of mental calculation. It was reported that non-experts mainly showed activity in the prefrontal and perisylvian areas, while experts with long-term training of at least three to five years, showed more activation over premotor and parietal regions. It has also been reported that abacus-based mental calculation (AMC) training was able to improve the working memory. Nevertheless, most of previous studies adopted cross-sectional designs to evaluate the results.
The aims of our study are to evaluate the relatively short term effect of a six-month abacus-based mental calculation (AMC) training on the functional connectivity network, and to investigate the possibility of AMC training effect transferring to untrained working memory tasks. A total of 70 human subjects were assigned to abacus (ABA) or control (CON) groups. The ABA group received 3.5 h AMC training per week for 25 weeks, whereas the control group performed general reading exercises. The total effective training time was 87.5 hours. This longitudinal study utilized standardized tests, including functional MRI (fMRI), and resting state fMRI. The validity and scale of this change were evaluated on both the behavioral level and the functional level under a relatively short-term training curriculum.
The results from post-training abacus (ABA) group showed that there were significant improvements in working memory index and serial addition reaction time. Functional MRI results revealed tendency of a shift in the activation when performing mental calculation task from prefrontal to the parietal regions. Regression analysis of functional connectivity and working memory index revealed that there was a significant correlation between working memory index and functional connectivity of left Broca area and left angular gyrus (n = 21, r (19)
= 0.429, p = 0.041). The correlation between working memory index and functional connectivity of left Broca area and left inferior frontal gyrus (proximal) also trended toward significance from (n = 21, r (19) = 0.085, p = 0.666) to (n = 21, r (19) = 0.386, p = 0.069). These combined results suggested that six months of AMC training can generalize to improvement on untrained working memory tests, and a midway paradigm shift (paradigm drift) can be expected along the fronto-parietal circuitry within the relatively long time required to become an expert.
Compared to the common practice of task repetition, AMC training is a more complex and interesting method of working memory training with a stronger sense of self-accomplishment through its step-by-step training curriculum. AMC is not only an arithmetic operation, but it might also be an appropriate learning tool to improve working memory capabilities by exercising
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visuo-motor and visuo-spatial skills, as partially evidenced by the current study. As a result of this educational neuroscience study, we might be able to start taking a different perspective on the traditional Chinese tool for not only calculation but also learning potential in the modern age.
Keywords: abacus, abacus-based mental calculation, functional connectivity, resting state, working memory, working memory training
Introduction
With a history tracing back various millenniums in different cultures, the abacus is an essential tool to human civilization growth and development. It is also a significant symbol in Chinese culture for trade and calculation. Inscription of Chinese abacus on the Representative List of the Intangible Cultural Heritage of Humanity was announced on December 2013 by UNESCO for its cultural significance and "training in abacus-based mental arithmetic is thought to improve a child’s attention span, memory and mental capability." (1).
Abacus experts have demonstrated extraordinary potential of mental calculation (2), and even beginner youths are often expected to improve in attention and mental focus abilities. Past imaging studies show a significant difference between experts and non-experts in brain functional areas when performing mathematical tasks (2-5). Non-experts show activity in the prefrontal and perisylvian areas, while experts with long-term training show more activation over premotor and parietal regions.
Most abacus-related studies in the past have cross-sectional designs, comparing abacus experts with non-experts. However, in the current Chinese social norm, with the availability of more active or creative extracurricular courses, very few children have the opportunity or willingness to pursue further abacus training after the initial one to two years, far less than the necessary training to become an expert. Therefore, we are curious about the effects of short-term abacus training on functional and behavioral levels. More importantly, how soon can we expect change after initializing training on the functional level and the behavioral level?
Children in Chinese society are encouraged to study for at least six months to one year to become acquainted with abacus-based mental calculation (AMC) and express significant behavioral improvement. The Chinese Abacus Association in Taiwan states that according to past experience, the greatest level of behavioral improvement is shown after six months to one year.
Irwing et al. suggested in 2008 a general intelligence improvement after receiving only 34 weeks of abacus training (6). Hu et al. suggested in 2011 potential enhancement on white matter integrity after abacus training for 3 years (7). Takeuchi et al. showed in 2013 that cognitive training can have probable effects on intrinsic brain activity and connectivity (8).
Therefore, in this study, we hypothesize potential midway paradigm drift, significant change in visuo-motor and visuo-spatial regional connectivity, and working memory behavioral
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improvement within a six-month abacus training period. After deploying standardized tests, functional MRI (fMRI), and resting state MRI (rsMRI), we evaluate the validity and scale of this change on both the behavioral level and the functional level under a relatively short-term training curriculum.
Methods
The fMRI scanning experiment of this study was performed in Taipei Wanfang Hospital. The total number of subjects was 70. The duration of this study was about half a year and two fMRI scans will be performed in total.
Twenty-seven children in total were excluded from the data analysis due poor quality MR images ( n=27). A total of forty-three healthy right-handed children data were analyzed in this study. The subjects are split into two groups: abacus training (ABA, n=21, 17 females, mean age = 9.61 years) and reading control (CON, n=22, 16 females, mean age = 10.57).
研究程序:
Figure 1. Research procedures.
Two abacus-based mental calculation (AMC) teachers were recruited to provide training for the ABA group over a six-month period. The group received 3.5 hours of training per week (2 hours of teacher-student lessons and 1.5 hours of practice homework) for 25 weeks. The CON group performed general reading exercises for 3.5 hours per week for 25 weeks. The total effective training time was 87.5 hours.
在每次fMRI影像掃描之前，會先在萬芳醫院，進行核磁共振攝影試驗前說明，約需二十分 鐘。每次的功能性核磁共振fMRI影像掃描約需四十分鐘，包括第一部分的腦部結構檢查與 第二部分執行心算任務時的掃描。在影像掃瞄時所進行的任務 ( task )有兩種，包括簡單與 複雜的十個數目字的累加計算能力檢測，以及空間能力檢測。
珠心算訓練為期6個月，在受訓期間，每個星期需接受2小時的珠心算訓練，且每天您須自
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主練習由試驗主持人所提供的珠心算練習題，每天20分鐘至30分鐘。且在受訓期間，您不 能接受其他心智或學術的訓練課程。
在珠心算訓練六個月後，將立即進行第二次的功能性核磁共振fMRI攝影。
試驗程序
□ 第一次核磁共振攝影試驗前說明：約需 20 分鐘
□ 第一次核磁共振攝影：約需 40 分鐘
□ 第一次數算能力及空間能力測驗：約需 30 分鐘
□ 第一次工作記憶能力測驗：約需 30 分鐘
□ 家庭與學習背景問卷調查：約需 20 分鐘
□ 珠心算訓練：6 個月
□ 第二次核磁共振攝影試驗前說明：約需 20 分鐘
□ 第二次核磁共振攝影：約需 40 分鐘
□ 第二次數算能力及空間能力測驗：約需 30 分鐘
□ 第二次工作記憶能力測驗：約需 30 分鐘
MRI 試驗程序
Table 1. MRI experiment procedures
The subjects were examined with fMRI, rs-fMRI functional connectivity (FC), and behavioral exams before and after the six-month training period. Abacus rating exams for the ABA group were provided at the end of the training period by the Chinese Abacus Association.
Image acquisition and preprocessing
The subjects were asked to perform a simple serial addition task (SSA) during the fMRI scan.
The task initialized with the presentation of a crosshair of 15 seconds, followed by a control or
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task period of 24 seconds. There were four control and four task blocks in a run. The control block included ten eight-digit random numbers presented in series with frequency of 0.5 Hz and subjects were required to gaze at the numbers without calculation. The block was then ended by a 4-s period of presenting two numbers and the subjects were asked to randomly select one number by a mouse-click. The task session presented ten random one-digit numbers with the same frequency and the subjects were instructed to sum the presented digits. At the end of each task block, the subjects were asked to select by mouse-click the correct sum from a 4-s queue of two numbers. During the rs-fMRI scan, subjects were instructed to keep their eyes closed, remain clear-minded, and think of nothing in particular.
Table 2. Experimental design of the task.
The fMRI images were acquired with a 1.5 T MAGNETOM Avanto system (Siemens Healthcare, Erlangen, Germany) using a T2*-weighted gradient-echo echo-planar imaging (EPI) sequence (TR/TE/FA = 3000 ms/50 ms/90°). For each subject, 104 volumes of 20 axial slices per volume were acquired. Resting state acquisitions were performed with the same sequence and parameters except TR = 2000 ms and total volume = 180.
Functional images analyses were performed by using SPM5 (9) and REST (10). The EPI data was realigned and spatially normalized into MNI template, then smoothed with a Gaussian kernel of 6 mm. Functional activations were obtained by modeling the data with GLM and group results were analyzed using one sample t-test. For rs-fMRI, after preprocessing, FC images underwent seed-based correlation analysis. Left prefrontal seeds were selected from the results of a task-related fMRI pilot study (11) (Table 1) including left fronto-insular cortex and left Broca area (LBA). The correlated results were transformed to approximate Gaussian distribution using Fisher’s z transformation. Between-group and within-group comparisons were assessed by two-sample and paired t-tests, respectively. For regression analysis, the ROIs were selected from
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activated prefrontal and parietal clusters within left inferior frontal gyrus (LIFG) and left angular gyrus (LAG), respectively, as determined using the anatomical automatic labeling (AAL) template (12).