Age-related differences in prestimulus subsequent memory effects assessed with event-related potentials

Abstract

Prestimulus subsequent memory effects (preSMEs) -differences in neural activity elicited by a task cue at encoding that are predictive of later memory performance -are thought to reflect differential engagement of preparatory processes that benefit episodic memory encoding. We investigated age differences in preSMEs indexed by differences in ERP amplitude just prior to the onset of a study item. Young and older adults incidentally encoded words for a subsequent memory test. Each study word was preceded by a task cue that signaled the judgment to perform on the word. Words were presented for either a short (300 ms) or a long (1000 ms) duration with the aim of placing differential benefits on engaging preparatory processes initiated by the task cue. ERPs associated with subsequent successful and unsuccessful recollection, operationalized here by source memory accuracy, were estimated time-locked to the onset of the task cue. In a late time-window (1000-2000 ms following onset of the cue), young adults demonstrated frontally distributed preSMEs for both the short and the long study durations, albeit with opposite polarities in the two conditions. This finding suggests that preSMEs in young adults are sensitive to perceived task demands. Although older adults showed no evidence of preSMEs in the same late time window, significant preSMEs were observed in an earlier time window (500-1000 ms) that were invariant with study duration. These results are broadly consistent with the proposal that older adults differ from their younger counterparts in how they engage preparatory processes during memory encoding.peer-reviewed)

The relationship between age, neural differentiation, and memory performance

“…The results from the different measures of the neuropsychological test battery are reported in Table 1. The pattern of age differences is essentially identical to our prior report (Koen et al, 2018), which is not surprising given the high degree of overlap between the samples (see Participants section of the Methods). There were significant effects of age, with older adults performing worse on tests assessing declarative memory, reasoning ability, category fluency, and processing speed.…”

Effects of age on pre-stimulus neural activity predictive of successful memory encoding: an fMRI study

“…In striking contrast to findings from prior fMRI studies employing intentional or semantically elaborative study tasks (e.g., Adcock et al, 2006;Park & Rugg, 2009;Addante et al, 2015;, here we identified exclusively negative pre-stimulus SMEs in both the cortex and the left hippocampus. The reasons for this striking divergence from prior findings are unclear, although part of the answer may lie in the plethora of procedural differences between the present and prior studies (as noted in the Introduction, a seemingly minor procedural variation can be sufficient to reverse the direction of electrophysiological measures of prestimulus SMEs; Koen et al, 2018). For example, to our knowledge, the present study is the first to use fMRI to examine pre-stimulus SMEs predictive of subsequent source, as opposed to item or associative, memory performance.…”

“…By contrast, an EEG study by Strunk & Duarte (2019) reported age-invariant effects in time-frequency measures of pre-stimulus neural activity elicited by pre-stimulus cues that signaled the modality of the upcoming study item. Contrary to the conclusions of Koen et al (2018), these authors proposed that older and young adults were equally capable of engaging pre-stimulus anticipatory processes that facilitate episodic encoding.…”

“…judgment. Although there is no correspondence between the directionality of fMRI and eventrelated potential (ERP) effects, it is noteworthy that Koen et al (2018) reported a conditiondependent reversal of ERP pre-stimulus SMEs (for similar findings, see Padovani et al, 2011).…”

“…One interpretation is that they reflect controlled processes elicited by the pre-stimulus cue that support the adoption of a specific task set or the engagement of task-appropriate preparatory processes (for review , Cohen et al, 2015). According to such 'preparatory' accounts (e.g., Park & Rugg, 2009;Addante et al, 2015;Koen et al, 2018), more effective preparation leads to more efficient processing of the study item, freeing up cognitive resources that can then be devoted to encoding operations. Alternately, pre-stimulus SMEs might reflect spontaneous fluctuations in neural states that are more or less conducive to effective encoding (e.g., Fernandez et al, 1999;Otten et al, 2002;Yoo et al, 2012;Salari & Rose, 2016;Schneider & Rose, 2016;Sweeney-Reed et al, 2016;Ezzyat et al, 2017;Cohen et al, 2019;Sadeh et al, 2019).…”