Changes in posterior cingulated cortex functional connectivity of resting-state functional magnetic resonance imaging in mild Alzheimer's disease

Abstract

Objective To investigate how functional connectivity changes within default-mode network related to posterior cingulated cortex employing resting-state functional MRI (tMRI). Methods fMRI was compared between 16 mild Alzheimer' s disease (AD) patients and 16 normal elder subjects. Regions of functional connectivity to posterior cingulated cortex were gathered by calculating temporal correlations in low frequency fMRI signal fluctuations. SPM2 was applied to calculate significant differences of connectivity between group and within group. Significance threshold was set up at the corrected P 5. A random effect two-example t test was performed by SPM2 to achieve significant difference of functional connection between groups ( P 5 ). Results Regions showing disrupted connectivity to posterior cingulated cortex were: ventral medial prefrontal cortex (MPFC), bilateral visual cortex, infero-temporal cortex (ITC), and left hippocampus, right thalamus, right dorsal-lateral prefrontal cortex ( DLPFC), and precuneus. There were also regions showing increased connectivity with leftward asymmetry, these regions included: MPFC, left ITC, bilateral DLPFC, left pre- central motor cortex and left basal ganglia. Conclusions Impairments of memory and high visual-related functions in AD can be explained by functional disconnection in resting-state. Remoldability is reserved in mild AD to compensate for brain function which is taxed by left hemisphere preferentially. Our findings suggest that resting-state fMRI might be an appropriate approach for evaluating AD brain mechanism. Key words: Alzheimer disease; Magnetic resonance imaging; Gyrus cinyuli