This study tested the two main neurocognitive models of dreaming by using cognitive data elicited from REM sleep in normals and narcoleptics. The two models were the ''activation-only'' view which holds that, in the context of sleep, overall activation of the brain is sufficient for consciousness to proceed in the manner of dreaming (e.g., Antrobus, 1991; Foulkes, 1993; Vogel, 1978); and the Activation, Input source, Modulation (AIM model), which predicts that not only brain activation level but also neurochemical modulatory systems (...) exert widespread effects upon dreaming (Hobson & McCarley, 1977; Hobson, Pace-Schott, & Stickgold, 2000). Mental activity was studied in nocturnal REM in 15 narcoleptics and 9 normal healthy persons and in REM at the onset of daytime naps and nighttime sleep (SOREM) in narcoleptics. The study was performed in the subjects' homes, using instrumental awakenings and ambulatory polysomnographic techniques, and focused upon visual vividness, mentation report length, improbable and discontinuous bizarre features, and reflective consciousness. Within each subject group, most cognitive variables tended to fluctuate in line with expected variations in circadian activation level. When comparing the cognitive variables between the two groups, reflective consciousness was clearly highest in narcoleptics, whereas improbabilities and discontinuities were lower, with mentation report length and visual vividness differing less between the groups. These findings are consistent with the AIM model of sleep mentation, but not with the activation-only model. (shrink)

Although we are beginning to understand the neurocognitive processes that underlie the emergence of dreaming, what accounts for the bizarre phenomenology of dreams remains debated. I address this question by comparing dreaming with waking mind wandering and challenging previous accounts that utilize bizarreness to mark a sharp divide between conscious experiences in waking and sleeping. Instead, I propose that bizarreness is a common, non-deficient feature of spontaneous offline simulations occurring across the sleep-wake cycle and can be tied to the specific (...) characteristics of spontaneous thought as being dynamic, unconstrained, (hyper)associative and highly variable in content. Rather than misrepresenting waking reality, bizarreness can be employed to investigate the very building blocks of spontaneous cognition. The absence of bizarreness in thought processes is imposed by automatic and deliberate cognitive constraints. By contrast, thought and memory processes operating on their own without such constraints are inherently marked by different degrees and types of bizarreness. (shrink)

Dream reports from 21 dreamers in which a metamorphosis of a person-like entity or animal occurred were coded for characters and animals and for inner states attributed to them (Theory of Mind). In myths and fairy tales, Kelly and Keil (1985) found that conscious beings (people, gods) tend to be transformed into entities nearby in the conceptual structure of Keil (1979). This also occurred in dream reports, but perceptual nearness seemed more important than conceptual nearness. In dream reports, most inanimate (...) objects involved in metamorphoses with person-like entities were objects such as statues that ordinarily resemble people physically, and moreover represent people. A metamorphosis of a person-like entity or animal did not lead to an increase in the amount of Theory of Mind attribution. We propose that a character-line starts when a character enters a dream; properties and Theory of Mind attributions tend to be preserved along the line, regardless of whether, metamorphoses occur on it. (shrink)

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)