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

Abstract

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,...

Brain regions supporting verbal memory improvement in healthy older subjects

“…In addition, participants recalled more words after the directed instructions for the SR condition and there was a significant correlation between semantic strategy scores and words recalled for the SR condition, a condition where this strategy can be used. These findings are similar to the ones found in healthy adult subjects 19 and other studies using different cognitive training in elderly subjects 21,22 and show that after a brief period of practice to apply efficient strategies older subjects can substantially improve their memory performance.…”

“…To date, only few studies have investigated the brain correlates after cognitive training in healthy older subjects. In one such study using positron emission tomography (PET), older adults' brain activity was assessed during encoding before and after the loci training − a mnemonic method to encode words which requires visualization of a series of items in familiar locations 22 . Older adults showed greater activity after training in occipitoparietal cortex related to improved performance.…”

Cognitive function in outpatients with perceived chronic stress

“…This pattern of result may suggest inefficient strategy implementation for the chronic stress group that is reflective of suboptimal executive control processes. Previous research comparing populations with assumed prefrontal-lobe dysfunction have yielded similar results, namely, that learning across trials in episodic memory tasks has been compromised (49,37).…”

Life Span Theory in Developmental Psychology

“…In addition to encompassing wide age ranges, future explorations of life span differences in behavioral plasticity may also include functional and anatomical neural measures to identify life span differences in the relation between behavioral and neuronal plasticity (for exemplary work, see Kramer et al, in press;Nyberg et al, 2003). Also, the focus on age differences in maximum level should be complemented by an emphasis on agedifferential changes in variances and covariances with practice (Hertzog, Cooper, & Fisk, 1996;Labouvie, Frohring, Baltes, & Goulet, 1973).…”