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J. Cognitive Neuroscience. 01/2010; 22:1348-1361.
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ABSTRACT: Human behavioral studies demonstrate that healthy aging is often accompanied by increases in memory distortions or errors. Here we used event-related fMRI to examine the neural basis of age-related memory distortions. We used the memory conjunction error paradigm, a laboratory procedure known to elicit high levels of memory errors. For older adults, right parahippocampal gyrus showed significantly greater activity during false than during accurate retrieval. We observed no regions in which activity was greater during false than during accurate retrieval for young adults. Young adults, however, showed significantly greater activity than old adults during accurate retrieval in right hippocampus. By contrast, older adults demonstrated greater activity than young adults during accurate retrieval in right inferior and middle prefrontal cortex. These data are consistent with the notion that age-related memory conjunction errors arise from dysfunction of hippocampal system mechanisms, rather than impairments in frontally mediated monitoring processes.
Journal of Cognitive Neuroscience 06/2009; 22(7):1348-61. · 5.18 Impact Factor
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ABSTRACT: Episodic memory enables individuals to recollect past events as well as imagine possible future scenarios. Although the episodic specificity of past events declines as people grow older, it is unknown whether the same is true for future events. In an adapted version of the Autobiographical Interview, young and older participants generated past and future events. Transcriptions were segmented into distinct details that were classified as either internal (episodic) or external. Older adults generated fewer internal details than younger adults for past events, a result replicating previous findings; more important, we show that this deficit extends to future events. Furthermore, the number of internal details and the number of external details both showed correlations between past and future events. Finally, the number of internal details generated by older adults correlated with their relational memory abilities, a finding consistent with the constructive-episodic-simulation hypothesis, which holds that simulation of future episodes requires a system that can flexibly recombine details from past events into novel scenarios.
Psychological Science 02/2008; 19(1):33-41. · 4.43 Impact Factor
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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 20s 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 20s 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.
Neuropsychologia 05/2007; 45(7):1363-77. · 3.64 Impact Factor
