The computing brain: abacus-based mental calculation correlation between abacus experts and normal subjects in PET study

Abacus-based mental calculation has been a unique Chinese culture for a long time. The abacus experts can perform complex computations mentally with exceptionally fast speed and high accuracy. However, these neural bases of computation processing are not yet clearly known. In this study, rCBF with O¹⁵ -water PET in experts and normal subjects were measured, and to investigate activation differences between the two groups in different level of computation abilities. Three paradigms were given during the testing, including covert reading, simple and complex contiguous addition problems. All the data were analyzed using SPM99 and MNI template. From the results, different ways of performing calculations between the two groups were seen. In the experts, tend to perform calculations with an imaginative abacus and all the computation steps in mind. All the intermediate and final results were processed and retrieved through this virtual abacus. Additional processes were also observed, with controlling and preparation of voluntary movement (putamen, caudate), and weightings of recording long alphabetic strings from the intermediate results during computation through the virtual abacus was very crucial (left supramarginal gyrus, BA40). In the normal subjects, no major differences in computation mechanism were observed both in Simple and Complex Conditions, but in Complex Calculations, high weightings of performing real computation (intraparietal sulcus, BA7) and recollecting intermediate results directly from working memory (left prefrontal cortex) were observed.