Alpha reactivity to first names differs in subjects with high and low dream recall frequency

Abstract

Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000–1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high and low-recallers.

Predicting Dream Recall: EEG Activation During NREM Sleep or Shared Mechanisms with Wakefulness?

“…However, we cannot rule out the existence of some stable neurophysiological differences that could contribute to DR and its quantitative/qualitative features. Indeed, Eichenlaub and coworkers (2014a, b;Ruby et al 2013) reported stable interindividual differences between HR and LR. HR showed a higher reactivity to their own first name sound and more intrasleep wakefulness compared to LR, consistently with the view that a higher cortical activation facilitates DR.…”

“…Sleep stages were visually scored in 20 s epochs, according to the standard criteria (Rechtschaffen and Kales 1968) and slow-wave sleep (SWS) scoring strictly followed the >75 μV amplitude criterion. The following sleep parameters were considered as dependent variables: (a) stage 1 latency; (b) stage 2 latency; (c) total sleep time (TST), defined as the sum of time spent in stage 1, stage 2, SWS and REM; (d) sleep stage duration; (e) wakefulness after sleep onset (WASO), in minutes; (f) number of awakenings; (g) number of arousals; (h) total bed time (TBT); (i) sleep efficiency index (SEI = TST/TBT × 100).…”

Increased Evoked Potentials to Arousing Auditory Stimuli during Sleep: Implication for the Understanding of Dream Recall

“…The reanalysis of EEG data (Eichenlaub et al, 2012, 2014a; Ruby et al, 2013a,b) enabled us to characterize more precisely the sleep macro and microstructure of HR and LR thanks to visual, semi-automatic and validated automatic methods. For intra-sleep awakenings no interaction between group and sleep stages was found (be it for the awakening index or for awakenings duration) showing that awakenings were longer in HR than in LR whatever the sleep stage.…”

EEG predictors of dreaming outside of REM sleep

“…First, several prior investigations have utilized between-subjects designs in which participants who recall dreams are compared to those who do not (Eichenlaub, Bertrand, Morlet, & Ruby, 2014;Marzano et al, 2011). This method is subject to substantial individual difference confounds, as participants with high dream recall (a stable trait) are known to differ from those with low dream recall on a number of dimensions, including personality traits (Hartmann, 1989;Hill, Diemer, & Heaton, 1997;Schredl, Nürnberg, & Weiler, 1996), and neurobiological traits (Eichenlaub, Nicolas, et al, 2014;Ruby et al, 2013). Studies have also varied substantially in their method of determining whether a participant dreamed, with some coding detailed open-ended subjective reports (Esposito et al, 2004), and others simply asking participants to report whether or "how much" they dreamed (Chellappa et al, 2012;Marzano et al, 2011;Scarpelli, Marzano, et al, 2015;Takeuchi et al, 2003).…”