Isolating the neural mechanisms of age-related changes in human working memory

Rypma, Bart; D’Esposito, Mark

doi:10.1038/74889

Cited by 510 publications

(420 citation statements)

References 27 publications

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“…The lack of differential frontal activation at posttest indicates that such processing was impaired for the older adults, possibly because of age-related changes in basic processing capacity. Working-memory decline in older age has been linked to reduced dorsal frontal activity (17), and age-related deficits in mental imagery tasks have been related to shrinkage of the prefrontal cortex and decline in working memory (18). Another basic processing resource is speed of mental information processing, and consistent with numerous previous studies (19) we observed pronounced age differences in a test of processing speed.…”

Section: Discussionsupporting

confidence: 78%

Neural correlates of training-related memory improvement in adulthood and aging

Nyberg

Sandblom

Jones

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

242

195

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Cognitive studies show that both younger and older adults can increase their memory performance after training in using a visuospatial mnemonic, although age-related memory deficits tend to be magnified rather than reduced after training. Little is known about the changes in functional brain activity that accompany training-induced memory enhancement, and whether age-related activity changes are associated with the size of training-related gains. Here, we demonstrate that younger adults show increased activity during memory encoding in occipito-parietal and frontal brain regions after learning the mnemonic. Older adults did not show increased frontal activity, and only those elderly persons who benefited from the mnemonic showed increased occipitoparietal activity. These findings suggest that age-related differences in cognitive reserve capacity may reflect both a frontal processing deficiency and a posterior production deficiency.T he existence of age-related deficits in episodic memory functioning are well documented (1). Given the impact of such deficits, much research has been directed at examining possible means of enhancing memory performance in older adults by various forms of cognitive support (2). One approach that has received considerable attention involves estimation of latent cognitive potential, or cognitive reserve capacity, in older age (3). In one variant of this approach, younger and older participants are given training in using a classical mnemonic, the method of loci (4), to memorize and retrieve words. This method involves learning to visualize a series of mental landmarks (e.g., places along one's route to work). After acquisition of the landmarks, the to-be-remembered information is linked to the various loci at the time of encoding. At test, the landmarks are mentally revisited in serial order, and the information associated with each locus is retrieved.Serial recall is substantially enhanced by the loci mnemonic for both younger and older adults (5, 6), demonstrating cognitive reserve capacity in aging (i.e., cognitive reserve capacity is defined as the ability to enhance one's memory performance after learning a mnemonic). However, the most striking aspect of previous findings is that age differences in memory performance are magnified rather than reduced after training (7). This pattern of results suggests an age-related decrease in cognitive reserve capacity. Little is known about the basis for this phenomenon. Baltes and Kliegl (7) hypothesized that older adults may have difficulty in forming novel relations between the landmarks and the to-be-remembered information (i.e., a difficulty in using rather than acquiring the mnemonic), and they proposed neurobiological constraints as a determinant of this deficit. However, no direct evidence for this account has been provided. Here, we present the results from an age-comparative positron emission tomography (PET) study of the neural underpinnings of acquisition and use of the loci method. MethodsTasks and Procedure. The whole experiment,...

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Section: Discussionsupporting

confidence: 78%

Neural correlates of training-related memory improvement in adulthood and aging

Nyberg

Sandblom

Jones

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

242

195

View full text Add to dashboard Cite

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“…Moreover, regardless of the performance differences, correctly performed trials used in the functional analyses produced comparable areas, magnitudes, and group differences in activation across studies. This finding lends confidence to conclusions about compensatory activation in older adults particularly in left prefrontal regions that have been the focus of some debate (DiGirolamo et al, 2001;Jonides et al, 2000;Nielson et al, 2002;Rypma and D'Esposito, 2000). The absence of a behavioral effect in the presence of a functional activation effect between groups could be used to argue that the activation differences between groups are more likely the result of an age effect, and not a performance effect.…”

Section: Discussionmentioning

confidence: 53%

“…More specifically, although the nature of the tasks used to study age-related changes in cognition and neurophysiology within imaging paradigms have varied from facial recognition to verbal working memory, some task nonspecific findings have begun to emerge. Older participants exhibit extraneous areas of activation and greater bilateral activation in functional homologues (i.e., analogous brain regions in the contralateral hemisphere) where younger adults exhibited asymmetrical activation (Cabeza, 2002;Cabeza et al, 1997b;Grady et al, 1994;Madden et al, 1997Madden et al, , 1999Nielson et al, 2002;Schachter et al, 1996, but see Grady et al, 1995;Jonides et al, 2000;Rypma and D'Esposito, 2000). A number of the imaging studies also report differences between younger and older adults in the inferior parietal lobule and the dorsomedial nucleus of the thalamus (DiGirolamo et al, 2001;Grady et al, 1994Grady et al, , 1995Grossman et al, 2001;Madden et al, 1997Madden et al, , 1999Nielson et al, 2002).…”

Section: Introductionmentioning

confidence: 98%

Frontal recruitment during response inhibition in older adults replicated with fMRI

2003

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Recent research has explored age-related differences in multiple areas of cognitive functioning using fMRI, PET, and SPECT. However, because these studies used different tasks, subjects, and methods, little is known about whether the results of these studies are generalizable or repeatable. The present study replicated a previous study [Psychol. Aging 17 (2002) 56] NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page.NeuroImage, Vol 20, No. 2 (October 2003): pg. 1384-1392. DOI. This article is © Elsevier and permission has been granted for this version to appear in e-Publications@Marquette. Elsevier does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Elsevier. 2 using the same Go/No-go task with a subset of 11 of the original older adult subjects, and using the same fMRI scanner and imaging methods. A direct comparison was made between these participants at Time 1 and Time 2 for both behavioral and functional data. These participants were also compared to a new young adult group of 11 participants. Although the current young adult group did not perform as well as the original young adult group, the original finding of enhanced left prefrontal activation in older adults relative to younger adults was replicated. Furthermore, when comparing Time 1 to Time 2, older adults exhibited comparable areas of activation, but significantly greater magnitude of activation at Time 1 in a few clusters. The findings indicate that older adults exhibit more bilateral brain activity during this task than young adults, which appears compensatory and is repeatable over time. The magnitude of regional activation, however, may vary with extraneuronal factors such as signal-to-noise ratio or task experience. This study adds to existing research suggesting that bilateral frontal activation is a predominant finding in the aging literature, and not specific to certain tasks in age group comparisons.

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“…More recent data suggest that the main locus of dysfunction associated with working memory deficits is a more specific region of the PFC -the dorsal lateral PFC (Ref. 38). Research over the last two decades suggests that dopamine modulates how well the PFC makes use of briefly activated cortical representations to circumvent constant reliance on environmental cues and to regulate attention towards relevant stimuli and appropriate responses 20 .…”

Section: Neurobiological Levelmentioning

confidence: 99%