Remembering the past and imagining the future: Common and distinct neural substrates during event construction and elaborationMethodsParticipantsStimuliScanningEvent tasksControl tasksPost-scan interviewData acquisitionData processing and statistical analysesResultsBehavioral resultsRegions commonly engaged by past and future eventsRegions differentially engaged by past and future eventsNeural correlates of event construction and elaborationDiscussionNeural overlap during past and future constructionNeural differentiation of past and future event constructionCommon network mediating the elaboration of past and future eventsDistinct regions mediating past and future elaborationThe adaptive significance of past and future episodic thinkingAcknowledgementsExamples of specific past and future events generated by a pilot participantPast event (5 years ago; cue=star)Future event (in 5 years; cue=dress)ReferencesNeuropsychologia 45 (2007) 1363–1377Remembering the past and imagining the future: Common and distinctneural substrates during event construction and elaborationDonna Rose Addisa,b,∗, Alana T. Wonga,b, Daniel L. Schactera,baDepartment of Psychology, Harvard University, Cambridge, MA, United StatesbMGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, United StatesReceived 1 July 2006; received in revised form 26 October 2006; accepted 27 October 2006Available online 28 November 2006AbstractPeople can consciously re-experience past events and pre-experience possible future events. This fMRI study examined the neural regionsmediating the construction and elaboration of past and future events. Participants were cued with a noun for 20 s and instructed to constructa past or future event within a specified time period (week, year, 5–20 years). Once participants had the event in mind, they made a buttonpress and for the remainder of the 20 s elaborated on the event. Importantly, all events generated were episodic and did not differ on a numberof phenomenological qualities (detail, emotionality, personal significance, field/observer perspective). Conjunction analyses indicated the lefthippocampus was commonly engaged by past and future event construction, along with posterior visuospatial regions, but considerable neuraldifferentiation was also observed during the construction phase. Future events recruited regions involved in prospective thinking and generationprocesses, specifically right frontopolar cortex and left ventrolateral prefrontal cortex, respectively. Furthermore, future event construction uniquelyengaged the right hippocampus, possibly as a response to the novelty of these events. In contrast to the construction phase, elaboration wascharacterized by remarkable overlap in regions comprising the autobiographical memory retrieval network, attributable to the common processesengaged during elaboration, including self-referential processing, contextual and episodic imagery. This striking neural overlap is consistent withfindings that amnesic patients exhibit deficits in both past and future thinking, and confirms that the episodic system contributes importantly toimagining the future.© 2006 Elsevier Ltd. All rights reserved.Keywords: Episodic; Autobiographical memory; fMRI; Hippocampus; FrontopolarEpisodic memory allows individuals to project themselvesbackward in time and recollect many aspects of their pre-vious experiences (Tulving, 1983). Numerous cognitive andneuroimaging studies have attempted to delineate the psycholog-ical and biological properties of episodic memory. One commonassumption in such studies is that episodic memory is primarilyor entirely concerned with the past. However, a growing numberof investigators have begun to approach episodic memory in abroader context, one that emphasizes both the ability of individ-uals to re-experience episodes from the past and also imagine orpre-experience episodes that may occur in the future (Atance &O’Neill, 2001, 2005; Buckner & Carroll, in press; D’Argembeau∗Corresponding author at: Department of Psychology, Harvard University,William James Hall, Rm. 854, 33 Kirkland Street, Cambridge, MA 02138,United States. Tel.: +1 617 495 3856; fax: +1 617 496 3122.E-mail address: [email protected] (D.R. Addis).& Van der Linden, 2004; Gilbert, 2006; Hancock, 2005; Klein& Loftus, 2002; Schacter & Addis, in press; Suddendorf &Busby, 2005; Tulving, 1983, 2002; Williams et al., 1996). Fromthis perspective, both past and future event representations canbe episodic in nature, containing rich contextual details aboutevents that are specific in time and place.Some evidence for this close linkage of past and future eventscomes from studies of patients with episodic memory deficits.For example, Tulving (1985) reported that patient K.C., a patientwho suffered from total loss of episodic memory as a result ofhead injury that produced damage to the medial temporal andfrontal lobes. Consequently, he was unable to imagine specificevents in his personal future (Tulving, 1985) despite no loss ingeneral imagery abilities (Rosenbaum, McKinnon, Levine, &Moscovitch, 2004). A more systematic investigation in anotheramnesic patient, D.B. (Klein & Loftus, 2002) revealed that he,too, exhibited deficits in both retrieving past events and imag-ining future events. Interestingly, this deficit in imagining the0028-3932/$ – see front matter © 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.neuropsychologia.2006.10.0161364 D.R. Addis et al. / Neuropsychologia 45 (2007) 1363–1377future was specific to D.B.’s personal future; he could still imag-ine possible future events in the public domain (e.g., politicalevents and issues). Taken together, the pattern of deficits inthese patients suggest there may be something unique aboutimagining personal future events above and beyond the gen-eral processes involved in constructing non-personal events andgenerating images.Another population exhibiting episodic memory impairments– suicidally depressed individuals – show reduced specificity ofboth past and future autobiographical events, and notably, thereduction in specificity of past and future events is significantlycorrelated (Williams et al., 1996). Moreover, Williams and col-leagues demonstrated that in healthy individuals, manipulationsthat reduced the specificity of past events (e.g., instructions orcues which induce a general retrieval style) also reduced thespecificity of subsequently generated future events.