Default Mode Network Analysis in Healthy Volunteers

The default mode network (DMN) is an organized network of brain structures involved in brain activity that may be observed in the resting state. In the course of the performance of an experimental cognitive task during functional MRI examination (fMR), these regions manifest as "deactivations". The main areas involved in this network are the ventromedial prefrontal cortex/anterior cingulate cortex, posterior cingulate cortex/precuneus and angular gyrus/inferior parietal cortex. In a group of 10 healthy volunteers we employed the following approaches to the detection of DMN: deactivations related to a visual spatial memory task; seed functional connectivity from the specific region of interest (cluster posterior cingulate cortex/precuneus); and independent component analysis (ICA). We then sought correlations between the MRI signal and the results of the visuo-spatial memory task and the Addenbrook cognitive examination (ACE), in concrete terms with the ACE verbal fluency subscore (VET), and memory. The ICA approach revealed a higher correlation rate with the results from functional connectivity compared with pure deactivation mapping. We found correlation between MRI signal in the cluster posterior cingulate cortex/precuneus and VFT performance.