Elsevier

Neuropsychologia

Volume 45, Issue 7, 2007, Pages 1363-1377
Neuropsychologia

Remembering the past and imagining the future: Common and distinct neural substrates during event construction and elaboration

https://doi.org/10.1016/j.neuropsychologia.2006.10.016Get rights and content

Abstract

People can consciously re-experience past events and pre-experience possible future events. This fMRI study examined the neural regions mediating the construction and elaboration of past and future events. Participants were cued with a noun for 20 s and instructed to construct a past or future event within a specified time period (week, year, 5–20 years). Once participants had the event in mind, they made a button press and for the remainder of the 20 s elaborated on the event. Importantly, all events generated were episodic and did not differ on a number of phenomenological qualities (detail, emotionality, personal significance, field/observer perspective). Conjunction analyses indicated the left hippocampus was commonly engaged by past and future event construction, along with posterior visuospatial regions, but considerable neural differentiation was also observed during the construction phase. Future events recruited regions involved in prospective thinking and generation processes, specifically right frontopolar cortex and left ventrolateral prefrontal cortex, respectively. Furthermore, future event construction uniquely engaged the right hippocampus, possibly as a response to the novelty of these events. In contrast to the construction phase, elaboration was characterized by remarkable overlap in regions comprising the autobiographical memory retrieval network, attributable to the common processes engaged during elaboration, including self-referential processing, contextual and episodic imagery. This striking neural overlap is consistent with findings that amnesic patients exhibit deficits in both past and future thinking, and confirms that the episodic system contributes importantly to imagining the future.

Section snippets

Participants

Sixteen healthy, right-handed adults (seven male; mean age, 23 years; range, 18–33 years) with no prior history of neurological or psychiatric impairment participated in the study. Two participants were excluded due to an insufficient number of responses during the scan and post-scan interview. All participants gave informed written consent in a manner approved by the Harvard and Massachusetts General Hospital Institutional Review Boards.

Stimuli

Ninety-six nouns were selected from the Clark and Pavio

Behavioral results

Participants were successfully able to construct an event during scanning and describe the event in the post-scan interview for an average of 21.64 past (SD = 2.17) and 22.29 future (SD = 1.90) event tasks (out of a maximum of 24 of each event type). These events were then rated objectively for episodic specificity and only events with a score of 3 (i.e., specific in time and place) were included in subsequent analyses (examples of specific past and future events are provided in Appendix A).

Discussion

Our data support the hypothesis that both common and distinct neural substrates mediate past and future events, consistent with the findings of the one previous neuroimaging study that examined this question (Okuda et al., 2003). In the present study, however, we teased apart neural processes contributing to event construction and elaboration, demonstrating that neural differentiation of past and future events was maximal during construction while overlap was most striking during elaboration.

Acknowledgements

We thank W. Dale Stevens for assistance with data collection, Kelly S. Giovanello, Angela Gutchess, Elizabeth Kensinger and Itamar Kahn for assistance with statistical analyses, and anonymous reviewers for helpful comments. This research was supported by National Institute of Mental Health (NIMH) grant MH060941 and National Institute on Aging (NIA) grant AG08441, awarded to DLS.

References (80)

  • I.G. Dobbins et al.

    Memory orientation and success: separable neurocognitive components underlying episodic recognition

    Neuropsychologia

    (2003)
  • H. Eichenbaum

    The hippocampus and declarative memory: cognitive mechanisms and neural codes

    Behavioural Brain Research

    (2001)
  • P. Fletcher et al.

    The mind's eye—precuneus activation in memory-related imagery

    Neuroimage

    (1995)
  • P. Fletcher et al.

    “Sculpting the response space”—an account of left prefrontal activation at encoding

    Neuroimage

    (2000)
  • A. Gilboa

    Autobiographical and episodic memory—one and the same? Evidence from prefrontal activation in neuroimaging studies

    Neuropsychologia

    (2004)
  • D.L. Greenberg et al.

    The neuropsychology of autobiographical memory

    Cortex

    (2003)
  • N.A. Lazar et al.

    Combining brains: A survey of methods for statistical pooling of information

    Neuroimage

    (2002)
  • R.J. Maddock

    Retrosplenial cortex and emotion: New insights from functional imaging studies of the human brain

    Trends in Neurosciences

    (1999)
  • R.J. Maddock et al.

    Remembering familiar people: the posterior cingulate cortex and autobiographical memory retrieval

    Neuroscience

    (2001)
  • E.A. Maguire et al.

    The effect of adult-acquired hippocampal damage on memory retrieval: An fMRI study

    Neuroimage

    (2005)
  • M. Moscovitch et al.

    Strategic retrieval and the frontal lobes: Evidence from confabulation and amnesia

    Neuropsychologia

    (1997)
  • L. Nadel et al.

    Memory consolidation, retrograde amnesia and the hippocampal complex

    Current Opinion in Neurobiology

    (1997)
  • G. Northoff et al.

    Cortical midline structures and the self

    Trends in Cognitive Sciences

    (2004)
  • J. Okuda et al.

    Thinking of the future and the past: The roles of the frontal pole and the medial temporal lobes

    Neuroimage

    (2003)
  • J. Okuda et al.

    Participation of the prefrontal cortices in prospective memory: Evidence from a PET study in humans

    Neuroscience Letters

    (1998)
  • R. Poldrack et al.

    Functional specialization for semantic and phonological processing in the left inferior prefrontal cortex

    Neuroimage

    (1999)
  • R.S. Rosenbaum et al.

    The case of K.C.: Contributions of a memory-impaired person to memory theory

    Neuropsychologia

    (2005)
  • R.S. Rosenbaum et al.

    Visual imagery deficits, impaired strategic retrieval, or memory loss: Disentangling the nature of an amnesic person's autobiographical memory deficit

    Neuropsychologia

    (2004)
  • S. Steinvorth et al.

    Ecphory of autobiographical memories: An fMRI study of recent and remote memory retrieval

    Neuroimage

    (2006)
  • S. Steinvorth et al.

    Medial temporal lobe structures are needed to re-experience remote autobiographical memories: Evidence from H.M. and W.R.

    Neuropsychologia

    (2005)
  • T. Suddendorf et al.

    Making decisions with the future in mind: Developmental and comparative identification of mental time travel

    Learning and Motivation

    (2005)
  • S.A. Thompson et al.

    Dissociating person-specific from general semantic knowledge: Roles of the left and right temporal lobes

    Neuropsychologia

    (2004)
  • A.D. Wagner et al.

    Parietal lobe contributions to episodic memory retrieval

    Trends in Cognitive Sciences

    (2005)
  • M. Wheeler et al.

    Functional-anatomic correlates of remembering and knowing

    Neuroimage

    (2004)
  • D.R. Addis et al.

    Recollective qualities modulate hippocampal activation during autobiographical memory retrieval

    Hippocampus

    (2004)
  • A. Bechara et al.

    Emotion, decision making and the orbitofrontal cortex

    Cerebral Cortex

    (2000)
  • M. Brett et al.

    Region of interest analysis using an SPM toolbox [abstract] Presented at the 8th International Conference on Functional Mapping of the Human Brain

    Neuroimage

    (2002)
  • Buckner, R. L., & Carroll, D. C. (in press). Self-projection and the brain. Trends in Cognitive...
  • J.M. Clark et al.

    Extensions of the Paivio, Yuille, and Madigan (1968) norms

    Behaviour Research Methods, Instruments & Computers

    (2004)
  • N.J. Cohen et al.

    Memory, amnesia, and the hippocampal system

    (1993)
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