Dreaming as mind wandering: evidence from functional neuroimaging and first-person content reports

Abstract

Isolated reports have long suggested a similarity in content and thought processes across mind wandering (MW) during waking, and dream mentation during sleep. This overlap has encouraged speculation that both “daydreaming” and dreaming may engage similar brain mechanisms. To explore this possibility, we systematically examined published first-person experiential reports of MW and dreaming and found many similarities: in both states, content is largely audiovisual and emotional, follows loose narratives tinged with fantasy, is strongly related to current concerns, draws on long-term memory, and simulates social interactions. Both states are also characterized by a relative lack of meta-awareness. To relate first-person reports to neural evidence, we compared meta-analytic data from numerous functional neuroimaging (PET, fMRI) studies of the default mode network (DMN, with high chances of MW) and rapid eye movement (REM) sleep (with high chances of dreaming). Our findings show large overlaps in activation patterns of cortical regions: similar to MW/DMN activity, dreaming and REM sleep activate regions implicated in self-referential thought and memory, including medial prefrontal cortex (PFC), medial temporal lobe structures, and posterior cingulate. Conversely, in REM sleep numerous PFC executive regions are deactivated, even beyond levels seen during waking MW. We argue that dreaming can be understood as an “intensified” version of waking MW: though the two share many similarities, dreams tend to be longer, more visual and immersive, and to more strongly recruit numerous key hubs of the DMN. Further, whereas MW recruits fewer PFC regions than goal-directed thought, dreaming appears to be characterized by an even deeper quiescence of PFC regions involved in cognitive control and metacognition, with a corresponding lack of insight and meta-awareness. We suggest, then, that dreaming amplifies the same features that distinguish MW from goal-directed waking thought.

Neurobiological substrates of cognitive rigidity and autonomic inflexibility in generalized anxiety disorder

“…This was particularly the case for regions which form part of the default mode network, including the precuneus, which is implicated in episodic memory, visuospatial processing, self-reflection and aspects of consciousness (Fox, Spreng, Ellamil, Andrews-Hanna, & Christoff, 2015;Hannawi, Lindquist, Caffo, Sair, & Stevens, 2015;Kwok & Macaluso, 2015). Target appearance also attenuated activity within motor, auditory, and somatosensory areas, putatively reflecting the rich multisensory nature of internal thoughts (e.g., Fox, Nijeboer, Solomonova, Domhoff, & Christoff, 2013;Hasenkamp et al, 2012). Perhaps surprisingly, we did not find target-related changes within default mode network regions, notably posterior cingulate cortex, which is also linked to self-referential thoughts and worry (e.g., Christoff, Gordon, Smallwood, Smith, & Schooler, 2009;Paulesu et al, 2010).…”

Cerebral functional connectivity periodically (de)synchronizes with anatomical constraints

“…Finally, many groups have explored daydreaming, or mind wandering using functional imaging. The networks implied in these processes are mainly the default mode network (Kucyi and Davis 2014;Fox et al 2013), the executive control network (Christoff et al 2009) as well as their interplay (Vanhaudenhuyse et al 2011;Hasenkamp et al 2012). The dynamical properties of mind wandering have also been studied and characteristic frequencies on the order of 0.03-0.05 Hz were found (Bastian and Sackur 2013;Vanhaudenhuyse et al 2011).…”

Schooled in our own minds: Mind wandering and mindfulness in the makings of the curriculum

“…clear affinity between dream mentation and mind-wandering, suggesting that the latter can be a moderate version of the former (Fox, Nijeboer, Solomonova, Domhoff, & Christoff, 2013).…”