hide
Free keywords:
fMRI; Default mode; Autobiographical memory; Emotion; Functional dissociation
Abstract:
Humans spend a substantial share of their lives mind-wandering. This spontaneous thinking
activity usually comprises autobiographical recall, emotional, and self-referential components. While neu-
roimaging studies have demonstrated that a specific brain “default mode network” (DMN) is consis-
tently engaged by the “resting state” of the mind, the relative contribution of key cognitive components
to DMN activity is still poorly understood. Here we used fMRI to investigate whether activity in neural
components of the DMN can be differentially explained by active recall of relevant emotional autobio-
graphical memories as compared with the resting state. Our study design combined emotional autobio-
graphical memory, neutral memory and resting state conditions, separated by a serial subtraction control
task. Shared patterns of activation in the DMN were observed in both emotional autobiographical and
resting conditions, when compared with serial subtraction. Directly contrasting autobiographical and
resting conditions demonstrated a striking dissociation within the DMN in that emotional autobiographi-
cal retrieval led to stronger activation of the dorsomedial core regions (medial prefrontal cortex, posterior
cingulate cortex), whereas the resting state condition engaged a ventral frontal network (ventral striatum,
subgenual and ventral anterior cingulate cortices) in addition to the IPL. Our results reveal an as yet unreported dissociation within the DMN. Whereas the dorsomedial component can be explained by
emotional autobiographical memory, the ventral frontal one is predominantly associated with the resting
state proper, possibly underlying fundamental motivational mechanisms engaged during spontaneous
unconstrained ideation.
