LAUSR

Posterior cingulate cortex (PCC) is one of key nodes of default mode network. Recent studies have suggested that the connectivities between PCC and the other brain regions have important role in working memory performance. Therefore, we hypothesized that the local gray matter volume of PCC can affect the functions of frontal cortex. To address this issue, we acquired T1 weighted images for voxel-based morphometry, and measured time course of frontal oxygenated hemoglobin (Oxy-Hb) during letter verbal fluency task (VFT). Seventeen healthy volunteers were enrolled in the present study. We carried out the regression analysis between the gray matter concentration in PCC and the frontal oxy-Hb level during 0–60 s of VFT. This analysis found a significant cluster where the gray matter concentration is associated with frontal oxy-Hb level, even after adjustment of confounding factors including age and sex. Interestingly, there is no correlation between the gray matter concentration in frontal cortex and the frontal Oxy-Hb. These results suggest that gray matter volume of PCC rather than that of frontal cortex affects the extent of frontal activation during VFT. Our preliminary study may contribute to clarifying a role of PCC in the cognitive process.