The study yielded three main findings. First, in line with our predictions, the main DMN regions, posterior cingulate, ventral parietal cortex, and mPFC all showed an encoding/retrieval flip for externally presented events. Decreased activity in these regions was associated with successful Ext-Enc, but increased activity with successful Ext-Ret. This is the first study, to link the encoding/retrieval flip pattern directly to the brain's resting state network. Second, the encoding/retrieval flip in the DMN occurred regardless of whether events were internally-generated (Int-Enc+Int-Ret) or externally-presented (Ext-Enc+Ext-Ret). This finding argues against the idea that the DMN regions underlies and internal attention system. Third, HF showed an exception to the encoding/retrieval flip pattern. Hippocampal activity increased during both successful Int-Enc and Ext-Enc as well as Int-Ret and Int-Ret. This finding indicates that HF is not one of the core DMN regions, and is dissociated from the DMN when new memories are formed.
