Memory specificity is linked to repetition effects in event-related potentials across the lifespan

Abstract

Our memories depend on our brain's ability to form internal representations of relevant aspects of the world that can later be retrieved. The specificity with which past experiences can be remembered varies across the lifespan, possibly due to differences in how precisely information is encoded. This memory formation can be investigated through repetition effects, the common finding that neural activity is altered (suppressed or enhanced) when stimuli are repeated. However, whether differences in this indirect measure of memory formation relate to lifespan age differences in memory specificity has not yet been established. In the present study, we examined repetition effects in event-related potentials and their relation to recognition specificity. During incidental encoding, children (aged 7-9 years), young adults (18-30 years), and older adults (65-76 years) viewed repeated object images from different categories. During subsequent recognition, old, similar, and new objects were presented, allowing for a differentiation of memory for the specific item versus the general category. We identified neural repetition suppression effects in all age groups, and repetition enhancement for adults. Furthermore, individual item recognition performance comprising lure discrimination was positively associated with the magnitude of the neural repetition effects. These brain-behavior associations did not differ between age groups, indicating common neural mechanisms of memory formation. In sum, our findings demonstrate that neural repetition effects reflect encoding mechanisms that facilitate the formation of highly specific memory representations and highlight their significance as a neural indicator of individual differences in episodic memory encoding across the lifespan.

Tracking Age Differences in Neural Distinctiveness across Representational Levels

“…Less pronounced or no age-related deficits in item recognition memory, compared to, for example, associative memory, are not uncommon, especially under incidental encoding conditions (cf. Old and Naveh-Benjamin, 2008;Sommer et al, 2020). Nevertheless, older adults often tend to respond "old" more frequently than younger adults, contributing to their higher rates of false memories (Koutstaal and Schacter, 1997;Schacter et al, 1997;Fandakova et al, 2013Fandakova et al, , 2020 which was also observed in the present study.…”

Effects of Age Differences in Memory Formation on Neural Mechanisms of Consolidation and Retrieval

“…With regard to memory formation, while we observed generally similar mechanisms of memory encoding in older and younger adults in case of successful memory (see also (Sommer et al, 2020;Strunk & Duarte, 2019), older adults more often form memories that are of lower quality than those of younger adults. For example, we found that both age groups showed reliable oscillatory subsequent memory effects.…”

“…alpha/beta band, tend to form memory representations that have undergone less deep elaboration during encoding and may as a consequence contain fewer details. In other words, while the general mechanisms that underlie successful memory formation appear not to change across adulthood, the probability to successfully engage memory formation operations does seem to deteriorate as well as the level of detailedness or specificity of memories (see alsoSommer et al, 2020).Recent advances in neuroimaging analysis techniques allow characterizing memories with regard to their informational content, ultimately improving investigations of the detailedness of memories. Representational pattern analysis (RSA) is a multivariate analysis technique that describes neural activation patterns between stimuli in terms of their similarity or distance in geometric space(Kriegeskorte & Diedrichsen, 2019;Kriegeskorte & Kievit, 2013).…”