title: Mental time travel into the past and the future in healthy aged adults: an fMRI study.
abstract: Remembering the past and envisioning the future rely on episodic memory which enables mental time travel. Studies in young adults indicate that past and future thinking share common cognitive and neural underpinnings. No imaging data is yet available in healthy aged subjects. Using fMRI, we scanned older subjects while they remembered personal events (PP: last 12 months) or envisioned future plans (FP: next 12 months). Behaviorally, both time-periods were comparable in terms of visual search strategy, emotion, frequency of rehearsal and recency of the last evocation. However, PP were more episodic, engaged a higher state of autonoetic consciousness and mental visual images were clearer and more numerous than FP. Neuroimaging results revealed a common network of activation (posterior cingulate cortex, precuneus, prefrontal cortex, hippocampus) reflecting the use of similar cognitive processes. Furthermore, the episodic nature of PP depended on hippocampal and visuo-spatial activations (occipital and angular gyri), while, for FP, it depended on the inferior frontal and lateral temporal gyri, involved in semantic memory retrieval. The common neural network and behavior suggests that healthy aged subjects thought about their future prospects in the past. The contribution of retrospective thinking into the future that engages the same network as the one recruited when remembering the past is discussed. Within this network, differential recruitment of specific areas highlights the episodic distinction between past and future mental time travel.
authors.affiliation: Inserm-EPHE-Université de Caen/Basse-Normandie, Unité U923, GIP Cyceron, CHU Côte de Nacre, Caen, France. viard@cyceron.fr
authors.forename: Armelle
authors.initials: A
authors.lastname: Viard
authors.forename: Gaël
authors.initials: G
authors.lastname: Chételat
authors.forename: Karine
authors.initials: K
authors.lastname: Lebreton
authors.forename: Béatrice
authors.initials: B
authors.lastname: Desgranges
authors.forename: Brigitte
authors.initials: B
authors.lastname: Landeau
authors.forename: Vincent
authors.initials: V
authors.lastname: de La Sayette
authors.forename: Francis
authors.initials: F
authors.lastname: Eustache
authors.forename: Pascale
authors.initials: P
authors.lastname: Piolino
mesh_terms: D000368:Aged; D000375:Aging / Q000523:psychology*; D001921:Brain / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006179:Gyrus Cinguli / Q000502:physiology; D006624:Hippocampus / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007092:Imagination / Q000502:physiology; D008279:Magnetic Resonance Imaging; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology*; D009483:Neuropsychological Tests; D009778:Occipital Lobe / Q000502:physiology; D017397:Prefrontal Cortex / Q000502:physiology; D012660:Semantics; D013702:Temporal Lobe / Q000502:physiology; D013850:Thinking / Q000502:physiology