Previous studies have focused on changes in cerebral cortex activity accompanying memory formation and consolidation.Although the role of the parietal cortex in memory retrieval is well established,it is not well understood how parietal cortex memory consolidation for mathematical rules is related to granularity of stored information(i.e.,degree of detail or precision).Changes in parietal cortex activity associated with memory consolidation were analyzed using the Ebbinghaus paradigm and functional magnetic resonance imaging(fMRI).Over the course of 1 week,participants learned Boolean arithmetic tasks involving stimulus-response mapping rules containing either low-or high-granularity information.FMRI images were collected on day 1(i.e., low-granularity condition)and day 7(i.e.,high-granularity condition).The present data suggested that with practice,stored information was converted from a low-granularity to a high-granularity form.By following rule learning,it was hypothesized that the process of consolidation would involve an increased degree of rule representation granularity.Evidence for this process was reflected in parietal cortex activity.This finding was consistent with the hypothesis that mnemonic reconstruction in the parietal cortex is required for memory consolidation,and results suggested that information granules are formed during memory consolidation.The present results could increase the understanding of the relationship between memory consolidation and information granularity.
WANG XiuZhenZHONG NingLU ShengFuLI KunChengLANG ShuLei
Previous studies of young people have revealed that the left dorsolateral prefrontal cortex(DLPFC) plays an important role in inductive reasoning.An fMRI experiment was performed in this study to examine whether the left DLPFC was involved in inductive reasoning of MCI patients and normal agings,and whether the activation pattern of this region was different between MCI patients and normal agings.The fMRI results indicated that MCI patients had no difference from normal agings in behavior performance(reaction time and accuracy) and the activation pattern of DLPFC.However,the BOLD response of the DLPFC region for MCI patients was weaker than that for normal agings,and the functional connectivity between the bilateral DLPFC regions for MCI patients was significantly higher than for normal agings.Taken together,these results indicated that DLPFC plays an important role in inductive reasoning of agings,and the functional abnormity of DLPFC may be an earlier marker of MCI before structural alterations.
YANG YanHui1,3,LIANG PeiPeng2,3,LU ShengFu2,3,LI KunCheng1,3 & ZHONG Ning2,3,4 1 Xuanwu Hospital,Capital Medical University,Beijing 100053,China
