| Objective:To investigate the difference of the activated functional areas between AMC group that received abacus mental calculation training and Control group that did not receive AMC training when they engaged in same four mental calculation(including addition, subtraction, multiplication and division) with BOLD functional magnetic resonance imaging (BLOD-fMRI). In addition, to observe and compare the difference brain areas when the AMC group performed the addition tasks in different difficulty levels. To aim to explore the effect of AMC on the neural mechanisms of mental arithmetic in children.Material and Methods:Thirty-four school children were recruited in our study. Seventeen children trained with abacus mental calculation for 3 years (AMC group, keep practicing abacus operation and at least 3 to 5 hours a week) and seventeen children had no experience in both abacus operation and AMC (the untrained group, ie. Cotrol group). The two groups were matched in the age, family background, education background, and cognitive ability. All subjects without psychiatric disorders or brain and other organic diseases can cooperate to complete all the tasks, and their naked eyes or corrected vision are normal. All subjects showed average intelligence by basic cognitive ability test (version 2.0) and Raven standard reasoning test, and they were right-handed by Chinese handedness criteria. In order to guarantee the experiments were completed successfully, all participants were asked to finish the event-related potentials before the formal fMRI experiment to ensure them to fully understand the experiment content and process. Blood oxygenation level dependence (BOLD) fMRI scan was performed in a Siemens Trio 3.0T MRI scanner with an echo planar imaging (EPI) sequence when all subjects performed mental calculation tasks including addition, subtraction, multiplication, division and number-object control judging tasks. Meanwhile the AMC group children performed complex addition calculation tasks. Using a block-designed experiment,3 resting blocks and 3 stimulating blocks alternated. Statistical analyses for behavioral data were performed using SPSS 19.0. All data were analyzed by statistical parametric mapping 8 (SPM8). Data pre-processing included realignment, normalization and smoothing. Statistical analysis at the individual subject level was performed using a general linear model (GLM) in which the responses evoked by the addition were modeled by a standard hemodynamic response function. The data from individual analysis were superimposed onto Talairach template. Group analysis was performed by entering the single subject contrast maps into a second level analysis. Cerebral activations of group analysis were reported using a strict uncorrected threshold (P< 0.001, minimal cluster size,10 voxels) or family-wise error (FWE) corrected (P< 0.05). Central coordinates of functional areas were recorded and the anatomical locations were determined. The results of individual analysis were combined with the results of group analysis to compare the differences of the brain activated areas between two groups. At the same time, the neural mechanisms of the AMC group in different addition tasks were compared and analyzed. Results:The performance of the AMC group was better than the Control group, and the reaction time was shorter in AMC group than in Control group. But the correctness stepped down and the reaction time prolonged when the difficulty of calculation tasks increased in the AMC group.In the addition, subtraction, multiplication and division calculation tasks, bilateral occipital lobes (especially bilateral cuneus). left parietal lobe (posterior superior parietal lobe, i.e. precuneus) and bilateral cerebellums were activated in the AMC group. Right parietal lobe (superior parietal lobule, postcentral gyrus and precuneus) were activated in the part subjects in subtraction, multiplication and division calculation. In the small part of subjects, right prefrontal cortex, medial frontal gyrus, fusiform gyrus and lingual gyrus were also activated. The functional areas increased obviously in multiplication calculation and were few in addition calculation than the other tasks. Comparing complex to simple calculation tasks, the activated areas were more and much:right prefrontal cortex (right middle frontal gyrus) showed stronger activation and right superior parietal lobe were also greater activated in complex addition calculation.In the Control group, bilateral middle frontal gyrus, left inferior parietal lobule, left superior parietal lobule, left lingual gyrus, left fusiform gyrus, and bilateral cerebellums were obvious activated in four calculation tasks. Left inferior frontal gyrus and left middle occipital gyrus were also activated more or less in the part of subjects. The extent and magnitude of the functional areas decreased and focused obviously in the AMC group compared with the Control group. Although left parietal lobe overlapped to some extent in two groups, the exact dissection location was very different. The involved brain areas were left posterior superior parietal lobule (precuneus) in the AMC group and left inferior parietal lobe in the Control group. In addition, there was also superior parietal region in the Control group, but it didn’t include precuneus.Conclusion:The performance in the AMC group children is much better than that of the Control group, Which demonstrating abacus mental calculation could effectively improve children’s mental calculation ability.There is a significant difference of functional areas between the AMC group and the Control group for mental calculation. The AMC group activate mostly left posterior superior parietal lobules (precuneus) and bilateral cuneus, the most functional areas in the Control group are prefrontal cortex and left inferior parietal lobe; the results indicate that the calculation strategy of the AMC group is different from that of the Control group, the former mainly depend on visual-spatial strategy and the latter more rely on language strategy. These functional areas may work together as a whole in calculation, the posterior superior parietal lobule may play an important role in AMC. In addition, our data suggest that the occipital-parietal circuit may be recruited for imaginary abacus and its underlying neural correlates in AMC. For the same tasks, activated areas observed in the AMC group are fewer and localized, which shows AMC training can enhance the efficiency of nerve connection in the relative functional areas, and improve the utilization efficiency of neural resources. More activated regions such as the right superior parietal lobe, right prefrontal cortex (especially middle frontal gyrus) are probably related with the middle memory storage with the increasing difficulty. The right middle frontal gyrus in more difficult calculation indicate that it represent high-grade functional area and play a crucial role in complex calculation tasks. Our results help reveal cognitive mechanism in number processing and calculation in AMC children and develop novel approaches for the therapy of dyscalculia. |
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