title: EEG oscillations during sleep and dream recall: state- or trait-like individual differences?
abstract: Dreaming represents a peculiar form of cognitive activity during sleep. On the basis of the well-known relationship between sleep and memory, there has been a growing interest in the predictive role of human brain activity during sleep on dream recall. Neuroimaging studies indicate that rapid eye movement (REM) sleep is characterized by limbic activation and prefrontal cortex deactivation. This pattern could explain the presence of emotional contents in dream reports. Furthermore, the morphoanatomical measures of amygdala and hippocampus predict some features of dream contents (bizarreness, vividness, and emotional load). More relevant for a general view of dreaming mechanisms, empirical data from neuropsychological and electroencephalographic (EEG) studies support the hypothesis that there is a sort of continuity between the neurophysiological mechanisms of encoding and retrieval of episodic memories across sleep and wakefulness. A notable overlap between the electrophysiological mechanisms underlying emotional memory formation and some peculiar EEG features of REM sleep has been suggested. In particular, theta (5-8 Hz) EEG oscillations on frontal regions in the pre-awakening sleep are predictive of dream recall, which parallels the predictive relation during wakefulness between theta activity and successful retrieval of episodic memory. Although some observations support an interpretation more in terms of an intraindividual than interindividual mechanism, the existing empirical evidence still precludes from definitely disentangling if this relation is explained by state- or trait-like differences.
authors.affiliation: Department of Psychology, Sapienza University of Rome , Rome, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Scarpelli
authors.affiliation: Department of Psychology, Sapienza University of Rome , Rome, Italy.
authors.forename: Aurora
authors.initials: A
authors.lastname: D'Atri
authors.affiliation: Department of Psychology, Sapienza University of Rome , Rome, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Gorgoni
authors.affiliation: Department of Life, Health and Environmental Sciences, University of L'Aquila , L'Aquila, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Ferrara
authors.affiliation: Department of Psychology, Sapienza University of Rome , Rome, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: De Gennaro
keywords: EEG topography; continuity hypothesis; dream; episodic memory; frontal cortex; theta activity