Sleep-dependent memory triage: evolving generalization through selective processing

“…2011; Saletin and Walker, 2012; Abel et al., 2013; Inostroza and Born, 2013; Oudiette and Paller, 2013; Prince and Abel, 2013; Rasch and Born, 2013; Stickgold and Walker, 2013), this review focuses on the most established findings to aid their adaptation into education, therapeutic practice and…”

“Emotional—as compared to neutral—stimuli generally exhibit preferential consolidation over time (Yonelinas & Ritchey, 2015), but this effect is markedly enhanced by sleep (Stickgold & Walker, 2013).”

“All rights reserved. strengthening, neuronal traces of newly learned memories are thought to be integrated into existing memory networks and made more durable (Rasch, Büchel, Gais, & Born, 2007; Stickgold & Walker, 2013).”

“On the other hand, a variety of mechanisms bolster the retention of behaviorally relevant information [16,17].”

“Prior work on the effects of sleep on memory performance showed that sleep does not benefit all memories equally (for a review, see Stickgold & Walker, 2013).”

“Indeed it has been suggested that bizarreness arises out of the joining together of disparate elements (often from waking life; e.g., Revonsuo and Tarkko, 2002; Levin and Nielsen, 2007), which is also indicative of hyperassociativity.”

“In this context, the known beneficial effects of sleep for generalization and abstraction seem to be specifically important (e.g. Stickgold & Walker, 2013).”

“While forgetting may be the result of interference or decay, it is also possible that the brain ‘tags’ information for preferential processing during sleep, enhancing some memories while allowing others to fade.(47) Recent research suggests that information is tagged based on its importance to the individual, with thi…”

“For a memory to be retained for subsequent sleepdependent consolidation it must be selected for retention and further processing during the intervening wake period (Stickgold and Walker, 2013).”

“…(SOs), sleep spindles, and their coupling), have been linked to aging and cognitive decline [4 e 6], schizophrenia [7 e 9], post-traumatic stress disorder [10,11], autism [12,13], as well as facets of cognitive, memory, and emotional functioning in healthy individuals (for reviews see [2,3,14]).”

“The speech-error result is compatible with a growing body of evidence that sleep has a particular role to play in the transformation rather than stabilization of recent memories, such that after sleep, the new knowledge is in a more useful state for future actions (Stickgold & Walker, 2013).”

“Several influential models, including Active Systems Consolidation (Rasch and Born, 2013), Synaptic Homeostasis (Tononi and Cirelli, 2006, 2014), Memory Triage (Stickgold and Walker, 2013), and Information Overlap to Abstract (Lewis and Durrant, 2011), have proposed mechanisms by which memory reactivation in sleep cou…”

“It has been shown that sleep contributes to memory consolidation processes (Maquet, 2001; Diekelmann and Born, 2010; Stickgold and Walker, 2013).”

“Recent work suggests that sleep can foster different forms of memory reorganization (Rasch & Born, 2013; Stickgold & Walker, 2013).”

“Hence, tagging [24] of these novel associations via the prefrontalhippocampal systems at learning may contribute to the stronger benefits of nocturnal sleep and daytime napping on semantically unrelated materials.”

“Payne JD, Ellenbogen JM, Walker MP, Stickgold R.”

“Additionally, sleep might even aid the restructuring of a problem representation by qualitatively transforming memories (Stickgold and Walker, 2013).”

“Based on these findings and recent theoretical proposals suggesting that sleep may 50 influence associative memory by facilitating the integration of multi-item sequences [3, 23], a 51”

“Indeed, sleep is well suited for addressing complex diseases that can impact multiple physiological systems (Tononi and Cirelli, 2006; Imeri and Opp, 2009; Stickgold and Walker, 2013).”

“Although the current work examined the influence of post-encoding TMS on a simple measure of how memory changes over time (retention), this approach can be used to more broadly understand the contribution of post-encoding processes to other ways in which memory and behavior changes over time [62, 83] aswell as tomodif…”

“For instance, it is well established that sleep is essential for sleep‐dependent learning and memory consolidation (Stickgold & Walker, 2013).”

“Often this generalization takes the form of ''gist extraction'' or abstraction from a small set of experiences to generate broader knowledge about the world (Lewis and Durrant, 2011; Stickgold and Walker, 2013; Wagner et al., 2004).”

“56), nor an interaction between session and group (F(1,23) = 0.”

“In the past decades many studies have suggested that memoryconsolidation is a function of sleep [1,2].”

“Sleep is thought to not only play an active role in the strengthening of memory traces, but also in the integration of overlapping information (Lewis & Durrant, 2011; Stickgold & Walker, 2013).”

“For example, salient information, especially if it is relevant for future use, is selectively consolidated, often at the expense of memory for less important information (Stickgold and Walker, 2013).”

“Recent work, however, suggests dynamic modification through memory organisation and reorganisation as memory traces are redistributed and memories evolve (Born & Wilhelm, 2012; Stickgold & Walker, 2005, 2013).”

“…researchers are acknowledging increasingly that consolidation goes beyond mere preservation, for example, to include how new memory traces become embedded into existing knowledge networks and undergo qualitative changes so entire new structures of knowledge might evolve (Stickgold & Walker, 2013).”

“Rather than uniformly enhancing consolidation, however, sleep ‘selects’ for consolidation the most salient or goalrelevant information (Stickgold & Walker, 2013, for review; Wilhelm et al., 2011).”

“A wealth of evidence shows that a period of sleep following learning preserves newly acquired knowledge better than a period of wakefulness (see Payne 2011, Stickgold and Walker 2013 for review).”

“It is exactly this additional complexity which may have brought about the more selective role of sleep in consolidation processes [82].”

“…in innumerable studies with various forms of information, including extraction of the hidden structure of digit strings (Wagner et al., 2004) and Serial Reaction Time Task patterns (Fischer et al., 2006), as well as incorporation of new words into an existing vocabulary (Tamminen et al., 2010).”

“These studies, as well as ours, are consistent with the theory that sleep serves to extract the ‘gist ’ of encoded memories while diminishing the details of each individual memory (Stickgold & Walker, 2013).”

“Furthermore, as memories get more strongly consolidated, the need to continue consolidating these memories should decrease, providing more opportunities for the consolidation of newer memories not yet bene fi ted from this process.”

“It is a selective process in which only some memories are strengthened (Stickgold & Walker, 2013), and the specific mechanisms by which the brain determines which memories to strengthen and which not remains unclear.”

“Furthermore, explicit “tagging” of an item as important or worth remembering during wakefulness modulates intentional memory processing and, therefore, determines the degree of subsequent recall.(118,120) Sleep preferentially promoted retention of items cued to be remembered – but not those cued to be forgotten – acro…”

“…it is tempting to speculate that sleep only consolidates memories which are efficiently built up and newly formed prior to the sleep period (Stickgold & Walker, 2013) and further studies will be required to unravel by which mechanisms the brain distinguishes between information that is…”

“(5) active neurological or psychiatric conditions; (6) a history of head trauma with loss of consciousness; (7) a Mini-Mental State Examination26 score < 26; or (8) a 15-item Geriatric Depression Scale27 score > 5.”

“20,25 Furthermore, the observed associations regarding generalization suggest that sleep does not just passively consolidate memories, but rather that it does so as an active process – referred to as “memory evolution” by Stickgold and Walker.”

“Sleep-related memory processes not only strengthen but also can optimize, organize, and transform information (Ellenbogen, Hu, Payne, Titone, & Walker, 2007; Stickgold & Walker, 2013).”

“An alternative account is based on the observation that post-encoding processes affect systems consolidation of memories and their integration into existing cognitive schemas (Diekelmann and Born, 2010; Stickgold and Walker, 2013).”

“This explanation is speculative at this point and the mechanisms that are involved in selective memory consolidation still remain unclear (Stickgold & Walker, 2013).”

“This sleep-dependent consolidation is thought to stem from the reactivation and integration of newly encoded memories into preexisting and permanent knowledge networks (Stickgold & Walker, 2013), a process that jointly involves system and synaptic-consolidation processes (Dudai, 2004).”

“Similarly, the lack of identity feelings has parallels to sleep conditions or to conditions of dementia (Jetten et al., 2010; Stickgold and Walker, 2013), where the corticolimbic network is so broken and unstable that a coherent resonance pattern, creating identity, cannot be established.”

“strongly encoded memories [33], or because sleep is believed to be important for integrating and processing complex information [34], the majority of Drosophila sleep studies have used multisensory operant conditioning assays.”

“…during sleep is held to go beyond the making permanent of individual items, to involve also a process of abstraction from experience, and the integration of new experiences into current schemata, so that the gist of experiences is distilled (Lewis and Durrant, 2011; Stickgold and Walker, 2013).”

“Interestingly, these effects can be selective, with sleep enhancing memory for some content more than others (e.g., Payne, 2011; Stickgold & Walker, 2013, for review).”

“memories that noticeably stand-out) are strengthened ahead of non-salient memories (Stickgold and Walker, 2013; Wilhelm et al., 2011).”

“…Learning Systems Account (McClelland, McNaughton, & O’Reilly, 1995) predicts that during offline consolidation, there is integration of experience with prior knowledge, abstracting salient features away from the episodic details in the process (termed memory “triage” by Stickgold & Walker, 2013).”

“Sleep has been suggested to strengthen a memory through two parallel actions: stabilization and enhancement (Walker, 2005; Stickgold and Walker, 2013).”

“Finally, since sleep itself plays a central role in the consolidation of memories into cognitive schemata (e.g., Lewis & Durrant, 2011; Stickgold & Walker, 2013) as well as the retrieval of appropriate mental models (Fortier-Brochu & Morin, 2010), sleep problems are likely to slow the development…”

“…that sleepdependent memory processes operate in a more discerning manner, such that information is selectively consolidated on the basis of its salience or relevance for future recall (Born & Wilhelm, 2012; Payne & Kensinger, 2010; Rasch & Born, 2013; Stickgold, 2013; Stickgold & Walker, 2013).”

“In addition to the importance of sleep for body repose, sleep is crucial for the reactivation, consolidation and restructuring of daytime memories (Rasch & Born, 2013; Stickgold & Walker, 2013).”

“This dynamic consolidation process is likely a very useful mechanism of plasticity that allows the brain to continually revisit and update existing stored memories or representations in light of newly acquired information (20, 30).”

“Besides promoting the mere stabilization of the newly acquired information, sleep has been shown to benefit the extraction of gist information (Fischer et al., 2006; Gómez et al., 2006; Payne et al., 2008; Durrant et al., 2011; Stickgold and Walker, 2013; Wilhelm et al., 2013).”

“Although the mechanisms and functions of sleep is still debated, it is a common biological need and clearly important for the learning process and memory consolidation (Graves et al., 2003; Jenkins and Dallenbach, 1924; Leibowitz et al., 2006; Marshall and Born, 2007; Rasch and Born, 2013; Stickgold and Walker, 2013;…”

“Of relevance, sequential theories of memory consolidation suggest that the same memory traces are processed in different sleep stages across the night or over multiple nights [45, 47–50].”

“Altogether, the available data point to the concerted association, during NREM and REM sleep, of electrophysiological and molecular mechanisms responsible for the sequential processing, i.e., reorganization and synaptic consolidation of memory traces during the NREM–REM sleep cycle [11,25,70].”

“…such as gaining insight into hidden structures, schema abstraction, and the extraction of gist knowledge (Lewis and Durrant, 2011; Payne, 2011a; Stickgold and Walker, 2013; Landmann et al., 2014), and there is first evidence that auditory cueing during SWS enhances these processes, e.g.,…”

“Another account is that REM sleep functions to process emotional content [24], and to the extent that an unfinished prospective memory intention is deemed stressful [48], prospective memories may undergo emotional processing during REM sleep.”

“…2007, 2011) and philosophy (see e.g. De Brigard 2014; Sutton 1998, 2010; Michaelian 2011; Robins 2016), and it is increasingly being acknowledge in neuroscience (see, e.g. Stickgold and Walker 2013; Eichenbaum and Cohen 2014; Richards and Frankland 2017) that this is not how memory systems work.”

“The neural mechanisms underlying a memory’s post-encoding evolution through stabilization and enhancement remains obscure, although recent research has led to an increasingly nuanced sense of the timing and brain states involved in these processes (Rasch & Born, 2013; Stickgold & Walker, 2013).”