Abstract
Magnetic resonance diffusion tensor imaging (DTI) is a kind of effective measure to do non-invasive investigation on
brain fiber structure at present. Studies of fiber tracking based on DTI showed that there was structural connection of
white matter fiber among the nodes of resting-state functional network, denoting that the connection of white matter was
the basis of gray matter regions in functional network. Nevertheless, relationship between these structure connectivity
regions and functional network has not been clearly indicated. Moreover, research of fMRI found that activation of
default mode network (DMN) in Alzheimer's disease (AD) was significantly descended, especially in hippocampus and
posterior cingulated cortex (PCC). The relationship between this change of DMN activity and structural connection
among functional networks needs further research. In this study, fast marching tractography (FMT) algorithm was
adopted to quantitative calculate fiber connectivity value between regions, and hippocampus and PCC which were two
important regions in DMN related with AD were selected to compute white matter connection region between them in
elderly normal control (NC) and AD patient. The fiber connectivity value was extracted to do the correlation analysis
with activity intensity of DMN. Results showed that, between PCC and hippocampus of NC, there exited region with
significant high connectivity value of white matter fiber whose performance has relatively strong correlation with the
activity of DMN, while there was no significant white matter connection region between them for AD patient which
might be related with reduced network activation in these two regions of AD.
