The dorsal and ventral default mode networks are uniquely modulated by the valence and vividness of imagined events
Lee, S., Parthasarathi, T., & Kable, J. W.
Humans often engage in mental time travel, or imagining possible future events. Recent work has shown that the brain’s default mode network (DMN) is active when people imagine the future. Here we test whether future imagination can be decomposed into dissociable psychological processes linked to different subcomponents of the DMN. While measuring brain activity with fMRI as subjects imagine future events, we manipulate the vividness of these events to modulate the demands for scene construction, and we manipulate the valence of these events to modulate the demands for evaluation. We found that activity in one subcomponent of the DMN, the ventral DMN or medial temporal lobe subsystem, responds to the vividness but not the valence of imagined events. In contrast, activity in a different subcomponent, the dorsal or core DMN, responds to the valence but not the vividness of imagined events. The separate modifiability of different subcomponents of the DMN by vividness and valence provides strong evidence for a dissociation between neurocognitive processes involved in (1) the construction of novel, imagined scenes from individual components from memory and (2) the evaluation of these constructed events as desirable or undesirable.