Dissociating the roles of the default-mode, dorsal, and ventral networks in episodic memory retrieval.

Emerging evidence indicates that three canonical brain networks--default-mode, dorsal, and ventral--play critical roles in many high-level cognitive tasks. The goal of the present study was to investigate the three network regions' involvement in episodic memory retrieval. To this end, we performed meta-analyses of prior functional MRI studies using a variant of the Remember-Know paradigm as the behavioral task. The analyses yielded three main findings. First, default-mode network regions, including the anterior and posterior midline cortex, the angular gyrus, and the medial temporal regions, were associated with greater activity during Remember (recollection) than during Know (familiarity) responses. This is consistent with the view that the default-mode network supports self-referential processing. Second, the dorsal network regions, including the dorsal frontal and parietal cortices, were associated with greater activity during Know (weak memory) than during Remember (strong memory) responses. This is consistent with the view that the dorsal network mediates executive control processing. Third, the ventral network regions, including the ventral frontal and parietal cortices, the insular cortex, and the caudate regions, increased activity with increasing familiarity strength. This is consistent with the view that the ventral network supports salience processing. These findings clarify the differential contributions of the default-mode, dorsal, and ventral networks to episodic memory retrieval and also indicate that many episodic retrieval-related activations may actually reflect more general attention/executive operations. More generally, the findings suggest that many activations observed in functional neuroimaging studies are components of networks that respond in concert rather than regions activated in isolation.