Training on Abacus-based Mental Calculation Enhances Resting State Functional Connectivity of Bilateral Superior Parietal Lobules.

Accumulating evidence indicates a positive effect of abacus-based mental calculation (AMC) training on various cognitive functions including short-term memory (STM). Our previous work has shown AMC training-induced activation changes in the frontal-parietal network (FPN) using task fMRI. However, whether AMC training-induced functional plasticity in the same brain network can be detected at resting state remains unknown. The current study aimed to address this question using resting state functional connectivity in a longitudinal AMC training experiment engaging a training group (18 subjects, age = 21.439 ± 0.565) and a control group (18 subjects, age = 21.113 ± 1.140). Our results revealed that the average functional connectivity strength within the FPN showing task activation changes was significantly enhanced after training in the AMC group, whereas it remained stable in the control group. Further analysis indicated that such connectivity increase in the AMC group was primarily driven by the enhanced coupling of bilateral superior parietal lobules (SPL). In addition, a significant and positive correlation between letter forward memory span and SPL connectivity was found at post-training session in the AMC group. While the weakest quartile of SPL connections ranking by pre-training connectivity strength showed the largest effect of enhancement after training, it was the strongest quartile of SPL connectivity that correlated the most with memory span at post-training session. These findings suggest that AMC training may enhance bilateral SPL functional connectivity, through which AMC training might exert a transfer effect to improve short-term memory capacity.