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. (shrink)

I argued that rapid eye movement dreaming is elaborative emotional encoding for episodic memories, sharing many features with the ancient art of memory. In this framework, during non–rapid eye movement, dream scenes enable junctions between episodic networks in the cortex and are retained by the hippocampus as indices for retrieval. The commentaries, which varied in tone from patent enthusiasm to edgy scepticism, fall into seven natural groups: debate over the contribution of the illustrative dream and disputes over the nature of (...) dreaming ; how the framework extends to creativity, psychopathology, and sleep disturbances ; the compatibility of the REM dream encoding function with emotional de-potentiation ; scepticism over similarities between REM dreaming and the AAOM ; the function of NREM dreams in the sleep cycle ; the fit of the junction hypothesis with current knowledge of cortical networks ; and whether the hypothesis is falsifiable. Although the groups in sections R1–R6 appear quite disparate, I argue they all follow from the associative nature of dreaming. (shrink)

This paper compares the free energy neuroscience now advocated by Karl Friston and his colleagues with that hypothesised by Freud, arguing that Freud's notions of conflict and trauma can be understood in terms of computational complexity. It relates Hobson and Friston's work on dreaming and the reduction of complexity to contemporary accounts of dreaming and the consolidation of memory, and advances the hypothesis that mental disorder can be understood in terms of computational complexity and the mechanisms, including synaptic pruning, that (...) have evolved to reduce it. (shrink)