Recalling and Forgetting Dreams: Theta and Alpha Oscillations during Sleep Predict Subsequent Dream Recall
Cristina Marzano,1 Michele Ferrara,2 Federica Mauro,1 Fabio Moroni,1,3 Maurizio Gorgoni,1 Daniela Tempesta,2 Carlo Cipolli,3 and Luigi De Gennaro1,4 1Department of Psychology, University of Rome “Sapienza,” 00185 Rome, Italy, 2Department of Health Sciences, University of L’Aquila, 67010 L’Aquila, Italy, 3Department of Psychology, University of Bologna, 40127 Bologna, Italy, and 4Associazione Fatebenefratelli per la Ricerca, Department of Neuroscience, Hosp. Fatebenefratelli, Isola Tiberina, 00186 Rome, Italy.
Under the assumption that dream recall is a peculiar form of declarative memory, we have hypothesized that (1) the encoding of dream
contents during sleep should share some electrophysiological mechanisms with the encoding of episodic memories of the awake brain
and (2) recalling a dream(s) after awakening from non-rapid eye movement (NREM) and rapid eye movement (REM) sleep should be
associated with different brain oscillations. Here, we report that cortical brain oscillations of human sleep are predictive of successful
dream recall. In particular, after morning awakening from REM sleep, a higher frontal 5–7 Hz (theta) activity was associated with
successful dream recall. This finding mirrors the increase in frontal theta activity during successful encoding of episodic memories in
wakefulness. Moreover, in keeping with the different EEG background, a different predictive relationship was found after awakening
from stage 2 NREM sleep. Specifically, a lower 8 –12 Hz (alpha) oscillatory activity of the right temporal area was associated with a
successful dream recall. These findings provide the first evidence of univocal cortical electroencephalographic correlates of dream recall,
suggesting that the neurophysiological mechanisms underlying the encoding and recall of episodic memories may remain the same
across different states of consciousness.
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