Functional connectivity of the posteromedial cortex

Aims Converging evidence supports the existence of a fronto-parietal association network which is most active during the baseline resting state and selectively deactivates during non-self directed cognitive tasks and neuropsychiatric conditions characterised by altered or abolished consciousness (Default Mode Network, DMN). Functional neuroimaging studies have suggested a central role for the precuneus and surrounding parietal areas (posteromedial cortex, PMC) in the control of baseline brain functioning within the DMN. Tracing studies in primates have shown that different areas within the PMC have different connectivity patterns, thus we set out to provide a systematic connectivity map of this key area using the resting-state functional connectivity approach. Methods Ten equispaced regions of interest were drawn within the PMC and submitted to seed-ROIs correlation analysis with fMRI in 17 subjects. Results We found a high level of local connectivity within the ten PMC components, with stronger functional intercorrelations among closely located areas. Moreover, anterior portions of PMC resulted to be part of a network implicated in the visuo-spatial guidance of movements, whereas posterior portions of PMC were interlinked with areas involved in processing self-relevant information and emotions. Conclusions The posterior PMC selectively correlates with a network showing considerable overlap with the DMN, thus suggesting that it makes essential contributions in self-referential processing and consciousness.