ABSTRACT
Objective To investigate the neural representations of long-term digital memory in human brain by functional magnetic resonance imaging (fMRI) technique. Methods 22 right-handed normal volunteers were recruited to participate in a test of long-term digital memory while the fMRI data were recorded. Control tasks were performed for the block-design. SPM 99 was used to analyze the data and to obtain the activated brain regions.Numbers of activated voxels were used to calculate lateralization index (LI). Results When the threshold was set as P＜0. 0001 ,using a one-sample t -test,the middle gyrus of the left frontal lobe(t=9.68) and the right cerebellum ( t = 9.85 ) were activated remarkably during the memory task. The subcortical structures including the thalamus (t=6.72) and the caudate (t=6.58) were also obviously activated during the memory task. LI of the numbers of activated voxels was 0.51. Conclusions The subcortical structures and the cerebellum as well as the cerebral cortex are collaborative to contribute to long-term digital memory function in human brain. The results also reveal that the functional areas of long-term digital memory in human brain are localized with the functional lateralization in the left hemisphere.
ABSTRACT
Objective To compare the characteristics and differences of the activation of the brain regions between the digital memory span task and digital working memory task.Methods 12 right-handed volunteers participated in a test of 7-digit memory span and a test of 2-digit working memory respectively, while the functional MR imaging (fMRI) data were recorded by a Seimens 1.5 T MR machine. Two control tasks were performed respectively and stimulation paradigms was block-design. SPM 99 was used to analyze the data and to localize the activated brain regions.Results The Brodmann area (BA) 6, 9 and 47 regions in the frontal lobe, the BA 7 and 40 regions in the parietal lobe, the cingulate gyrus, the hippocampus structures, the striatum and the cerebellum were activated by both tasks in comparison to their control tasks. Bilateral BA 18 and 19 regions of the occipital lobe without hemisphere predominance were the most activated regions by the digital memory span task, and the BA 37 region of the temporal lobe was also activated. However, the frontal lobe with left predominance was the most activated region by the digital working memory.Conclusion Different brain regions play distinct roles in different short-term digital memory tasks, and might be involved in different stages. The fMRI is a good tool for exploring the process of digits in the brain.