title: Similarities and differences in the default mode network across rest, retrieval, and future imagining.
abstract: The default mode network (DMN) has been identified reliably during rest, as well as during the performance of tasks such as episodic retrieval and future imagining. It remains unclear why this network is engaged across these seemingly distinct conditions, though many hypotheses have been proposed to account for these effects. Prior to generating hypotheses explaining common DMN involvement, the degree of commonality in the DMN across these conditions, within individuals, must be statistically determined to test whether or not the DMN is truly a unitary network, equally engaged across rest, retrieval and future imagining. To provide such a test, we used comparable paradigms (self-directed, uninterrupted thought of equal duration) across the three conditions (rest, retrieval, and future imagining) in a within-participant design. We found lower than expected pattern similarity in DMN functional connectivity across the three conditions. Similarity in connectivity accounted for only 40-50% of the total variance. Partial Least Squares (PLS) analyses revealed the medial temporal regions of the DMN were preferentially coupled with one another during episodic retrieval and future imagining, whereas the non-medial temporal regions of the DMN (e.g., medial prefrontal cortex, lateral temporal cortex, and temporal pole) were preferentially coupled during rest. These results suggest that DMN connectivity may be more flexible than previously considered. Our findings are in line with emerging evidence that the DMN is not a static network engaged commonly across distinct cognitive processes, but is instead a dynamic system, topographically changing in relation to ongoing cognitive demands. Hum Brain Mapp 38:1155-1171, 2017. © 2016 Wiley Periodicals, Inc.
authors: Department of Psychology, University of Toronto, Toronto, Ontario, Canada.|Rotman Research Institute - Baycrest, Toronto, Ontario, Canada.
authors: B
authors: 0000-0002-0266-8800
authors: B
authors: Bellana
authors: Rotman Research Institute - Baycrest, Toronto, Ontario, Canada.|Department of Applied Psychology and Human Development, University of Toronto, Toronto, Ontario, Canada.
authors: Z-X
authors: ZX
authors: Liu
authors: Department of Psychology, University of Toronto, Toronto, Ontario, Canada.|Rotman Research Institute - Baycrest, Toronto, Ontario, Canada.
authors: N B
authors: NB
authors: Diamond
authors: Department of Psychology, University of Toronto, Toronto, Ontario, Canada.|Rotman Research Institute - Baycrest, Toronto, Ontario, Canada.|Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors: C L
authors: CL
authors: Grady
authors: Department of Psychology, University of Toronto, Toronto, Ontario, Canada.|Rotman Research Institute - Baycrest, Toronto, Ontario, Canada.
authors: M
authors: M
authors: Moscovitch
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001921:Brain / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008959:Models, Neurological; D009434:Neural Pathways / Q000000981:diagnostic imaging* / Q000502:physiology; D012146:Rest; D013850:Thinking / Q000502:physiology; D055815:Young Adult
keywords: default mode network; episodic memory; functional connectivity; future imagining; resting state