Mechanisms Underlying Encoding of Short-Lived Versus Durable Episodic Memories

Abstract

We continuously encounter and process novel events in the surrounding world, but only some episodes will leave detailed memory traces that can be recollected after weeks and months. Here, our aim was to monitor brain activity during encoding of events that eventually transforms into long-term stable memories. Previous functional magnetic resonance imaging (fMRI) studies have shown that the degree of activation of different brain regions during encoding is predictive of later recollection success. However, most of these studies tested participants' memories the same day as encoding occurred, whereas several lines of research suggest that extended post-encoding processing is of crucial importance for long-term consolidation. Using fMRI, we tested whether the same encoding mechanisms are predictive of recollection success after hours as after a retention interval of several weeks. Seventy-eight participants were scanned during an associative encoding task and given a source memory test the same day or after ϳ6 weeks. We found a strong link between regional activity levels during encoding and recollection success over short time intervals. However, results further showed that durable source memories, i.e., events recollected after several weeks, were not simply the events associated with the highest activity levels at encoding. Rather, strong levels of connectivity between the right hippocampus and perceptual areas, as well as with parts of the self-referential default-mode network, seemed instrumental in establishing durable source memories. Thus, we argue that an initial intensity-based encoding is necessary for short-term encoding of events, whereas additional processes involving hippocampal-cortical communication aid transformation into stable long-term memories.

Pain to remember: a single incidental association with pain leads to increased memory for neutral items one year later

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Cortical thickness variation of the maternal brain in the first 6 months postpartum: associations with parental self-efficacy

“…First, although the statistical threshold levels used in the current study (both vertex-wise and cluster-wise thresholds less than 0.05) have also been used in other studies (e.g. (Ahveninen et al, 2013; King et al, 2015; Robinson et al, 2015; Schneider et al, 2014; Sneve et al, 2015; Takaya et al, 2016; Tchistiakova et al, 2014; Zorlu et al, 2017), we recognize those thresholds are relatively optimistic. Therefore, findings from the current study should be interpreted with caution until future studies use larger samples and more conservative thresholds (e.g.…”

Working Memory: Maintenance, Updating, and the Realization of Intentions

“…At supraspan challenges, the core working-memory maintenance system is insufficient for supporting performance, so long-term memory processes and an intact MTL system become vital. Further work will be crucial for elucidating the factors that influence whether information maintained in working memory becomes consolidated into longterm memory (see, e.g., Wagner 1999;Jensen and Lisman 2005;Sneve et al 2015).…”