Such stuff as dreams are made on? Elaborative encoding, the ancient art of memory, and the hippocampus

Abstract

This article argues that rapid eye movement (REM) dreaming is elaborative encoding for episodic memories. Elaborative encoding in REM can, at least partially, be understood through ancient art of memory (AAOM) principles: visualization, bizarre association, organization, narration, embodiment, and location. These principles render recent memories more distinctive through novel and meaningful association with emotionally salient, remote memories. The AAOM optimizes memory performance, suggesting that its principles may predict aspects of how episodic memory is configured in the brain. Integration and segregation are fundamental organizing principles in the cerebral cortex. Episodic memory networks interconnect profusely within the cortex, creating omnidirectional "landmark" junctions. Memories may be integrated at junctions but segregated along connecting network paths that meet at junctions. Episodic junctions may be instantiated during non-rapid eye movement (NREM) sleep after hippocampal associational function during REM dreams. Hippocampal association involves relating, binding, and integrating episodic memories into a mnemonic compositional whole. This often bizarre, composite image has not been present to the senses; it is not "real" because it hyperassociates several memories. During REM sleep, on the phenomenological level, this composite image is experienced as a dream scene. A dream scene may be instantiated as omnidirectional neocortical junction and retained by the hippocampus as an index. On episodic memory retrieval, an external stimulus (or an internal representation) is matched by the hippocampus against its indices. One or more indices then reference the relevant neocortical junctions from which episodic memories can be retrieved. Episodic junctions reach a processing (rather than conscious) level during normal wake to enable retrieval. If this hypothesis is correct, the stuff of dreams is the stuff of memory.

Opposite Impact of REM Sleep on Neurobehavioral Functioning in Children with Common Psychiatric Disorders Compared to Typically Developing Children

“…REM sleep’s physiological and psychological features also have been associated with more complex functions. For example, REM sleep has been suggested to heighten autobiographic memory (Horton and Malinowski, 2015; Malinowski and Horton, 2015) and to render previously encoded memories more distinct through its hyper-associative dreaming state (Llewellyn, 2013; Llewellyn and Hobson, 2015). Also, it is thought to incorporate these previously encoded memories into a broader vital context, thus embedding them in consolidated residuals of hypotheses, emotions, basic needs, and individual genetic traits (Kirov, 2013).…”

The Mediating Role of Pathological Worry in Associations Between Dissociative Experiences and Sleep Quality Among Health Staff

“…Drawing in evidence as findings of Van Der Kloet et al (2013) that longer REM sleep periods and less time spent awake at night among high dissociators, in which alterations in objective and subjective measures of sleep as a function of dissociation may be attributed to a somewhat rebound effect. In comparison to waking states, REM dreaming is more vivid and hyper-associational that remote memory material becomes more accessible during the REM sleep (Llewellyn, 2013). In response to stressful events or adversities, elevated levels of dissociation and alterations in sleep pattern both seem to serve facilitation of emotional information processing when the memory is emotion-laden in nature (Oathes & Ray, 2008;Walker & van der Helm, 2009).…”

The hippocampus facilitates integration within a symbolic field

“…There is emerging research regarding a state of ongoing dismemberment and consolidation of complex interrelated memories of all types that selectively strengthen and recombine elements of these traces and effect the network as a whole (Wamsley and Stickgold, ). It is recognized that much of this integration occurs in various forms of thinking, taking advantage of mental systems that are particularly active in various stages of sleep (Wamsley et al ., , ), but also can be taken advantage of while awake (Llewellyn, ).…”