Differential Contributions of Default and Dorsal Attention Networks to Remembering Thoughts and External Stimuli From Real-Life Events.

Episodic memories are typically composed of perceptual information derived from the external environment and representations of internal states (e.g., one's thoughts during prior episodes). To date, however, research has mostly focused on the remembrance of external stimuli, such that little is known about how internal mentation is represented within episodic memory. In the present fMRI study, we examined the neural correlates of these 2 components of episodic memories using a novel method of cuing memories from photographs taken during real-life events. We found that, compared with corresponding semantic memory tasks, memories for internal thoughts and external elements were associated with activity in brain areas supporting episodic recollection. Most importantly, however, the 2 kinds of memories also showed differential activation in large-scale brain networks: the remembrance of external elements was associated with greater activity in the dorsal attention network, whereas memories of internal thoughts mainly recruited default network areas. These findings shed new light on the representation of internal and external aspects of prior experience within episodic memory. The default network may contribute to the reinstatement of thoughts experienced during past events, whereas the dorsal attention network may support the allocation of attention to visuospatial features within episodic memory representations.