Neural oscillations and event-related potentials reveal how semantic congruence drives long-term memory in both young and older humans

Abstract

Long-term memory can improve when incoming information is congruent with known semantic information. This so-called congruence effect has widely been shown in younger adults, but age-related changes and neural mechanisms remain unclear. Here, congruence improved recognition memory in younger and older adults (i.e. congruence effect), with only weak evidence for age-related decline in one behavioral study. In an EEG study, however, no significant behavioral differences in the congruence effect could be observed between age-groups. In line with this observation, electroencephalography data show that, in both groups, congruence led to widespread differences in Event-Related Potentials (ERPs), starting at around 400 ms after stimulus onset, and theta, alpha and beta oscillations (4-20 Hz). importantly, these congruence-related eRps were associated to increases in memory performance for congruent items, in both age groups. finally, the described eRps and neural oscillations in the theta-alpha range (5-13 Hz) were less pronounced in the elderly despite a preserved congruence effect. together, semantic congruence increases long-term memory across the lifespan, and, at the neural level, this could be linked to neural oscillations in the theta, alpha and beta range, as well as eRps that were previously associated with semantic processing.

Semantic Congruence Drives Long-Term Memory and Similarly Affects Neural Retrieval Dynamics in Young and Older Adults

“…While age-related impairments could be expected on the basis of well-described memory deficits in older adults, it is also clear that semantic memory (i.e., long-term memory for facts independent of time and date) is often preserved until old age (Hedden and Gabrieli, 2004 ). Indeed, we could show a preserved semantic congruence effect in older adults (Packard et al, 2020 ), which is compatible with others showing a relatively small effect of aging on semantic relatedness and associated memory deficits (Crespo-Garcia et al, 2012 ). However, congruence-related ERPs and neural oscillations in the theta, alpha, and beta range (at encoding) were less pronounced in older subjects indicating age-related neural changes in the absence of behavioral deficits (Packard et al, 2020 ).…”

“…Indeed, we could show a preserved semantic congruence effect in older adults (Packard et al, 2020 ), which is compatible with others showing a relatively small effect of aging on semantic relatedness and associated memory deficits (Crespo-Garcia et al, 2012 ). However, congruence-related ERPs and neural oscillations in the theta, alpha, and beta range (at encoding) were less pronounced in older subjects indicating age-related neural changes in the absence of behavioral deficits (Packard et al, 2020 ).…”

“…EEG studies could provide further evidence for encoding specific effects by showing that semantic congruence accelerates the onset of the event-related potentials (ERPs) for successful memory encoding (Packard et al, 2017 ). Moreover, semantic congruence at encoding leads to differences in ERPs starting at around 400 ms after stimulus onset, as well as theta (4–8 Hz), alpha (8–13 Hz), and beta band (14–20 Hz) oscillations (Packard et al, 2020 ). Importantly, these congruence-related ERPs predicted increases in memory performance for congruent items, further suggesting that ERPs and neural oscillations underlie the congruence effect (Höltje et al, 2019 ; Packard et al, 2020 ).…”

“…Moreover, semantic congruence at encoding leads to differences in ERPs starting at around 400 ms after stimulus onset, as well as theta (4–8 Hz), alpha (8–13 Hz), and beta band (14–20 Hz) oscillations (Packard et al, 2020 ). Importantly, these congruence-related ERPs predicted increases in memory performance for congruent items, further suggesting that ERPs and neural oscillations underlie the congruence effect (Höltje et al, 2019 ; Packard et al, 2020 ).…”

Minimal phrase composition revealed by intracranial recordings

“…As such, we conducted an iEEG investigation using auditory recordings of minimal adjective-noun phrases across a large patient cohort (n = 18), conducting a study of minimal phrase composition using a mixture of intracranial recordings that either penetrated grey matter or were placed directly on the cortical surface. This method permits an exploration of neural oscillations in language, with oscillations being shown to index a range of computations in the brain (Buzsáki and Watson, 2012; Hovsepyan et al, 2020; Jensen et al, 2019; Packard et al, 2020), including lexico-semantic processes (Marko et al, 2019; Prystauka and Lewis, 2019).…”