Creative, internally-directed cognition is associated with reduced BOLD variability.

In a range of externally-directed tasks, intra-individual variability of fMRI BOLD signal has been shown to be a stronger predictor of cognitive performance than mean BOLD signal. BOLD variability's strong association with cognitive performance is hypothesised to be due to it capturing the dynamic range of neural systems. Although increased BOLD variability is also speculated to play a role in internally-directed thought, particularly when creative and flexible cognition is required, there is a relative lack of research exploring whether BOLD variability is related to internally-directed cognition. Thus, we investigated the relationship between BOLD variability and a key component of creativity - divergent thinking - in various tasks that required participants to think flexibly. We also determined whether any associations between BOLD variability and creativity overlapped with, or differed, from associations between mean BOLD signal and creativity. First, we performed task Partial Least Squares (PLS) analyses that compared BOLD signal (either mean or variability) during two future imagination conditions that differed in the amount of cognitive flexibility required: a Congruent condition in which autobiographical details (people, places, objects) comprising an imagined event belonged to the same social sphere (e.g., university) and an Incongruent condition in which details belonged to different social spheres and required greater cognitive flexibility to integrate. Results indicated that the Incongruent condition was associated with a widespread reduction in both BOLD variability and mean signal (relative to the Congruent condition), but in largely non-overlapping regions. Next, we used behavioral PLS to determine whether individual differences in performance on future simulation tasks as well as the Alternate Uses Task relates to BOLD variability and mean BOLD signal. Better performance on these tasks was predominantly associated with increases in mean BOLD signal and decreases in BOLD variability, in a range of disparate brain regions. Together, the results suggest that, unlike tasks requiring externally-directed cognition, superior performance on tasks requiring creative internal mentation is associated with less (not more) variability.