Different Kinds of Subjective Experience during Lucid Dreaming may have Different Neural Sub-strates

Recently, Allan Hobson published a brief essay in which he recognizes that lucid dreams are scientifically relevant and constitute a powerful tool for understanding the neurobiology of consciousness (Hobson, 2009). His statements are mostly based on the study by Voss et al. (2009), which employed refined mathematical analysis of electroencephalographic (EEG) recordings to tackle the neural basis of lucid dreaming. Several questions are open in this field, and we address one of them in this commentary.

Lucid dreams occur during rapid eye movement sleep (REMS), and most people present REMS every night. Still, lucid dreams are uncommon. A likely explanation for this discrepancy is that there exists more than one kind of REMS, and that the specific kind of REMS during which lucid dreams occur is rare, with spectral features that differentiate it from non-lucid REMS. Early studies provided evidence of a relationship between the level of lucidity and the overall amount of EEG power in the alpha band (8-12 Hz) (Ogilvie et al., 1982; Tyson, et al., 1984).

However, a subsequent study detected EEG power increase only within the beta band (13-20 Hz), restricted to the parietal region (Holzinger et al., 2006). More recent work found increased EEG power within the gamma band (peaking around 40 Hz) in frontal and fronto-lateral regions during lucid dreaming (Voss et al., 2009). Therefore, while there is evidence to suggest that lucid REMS present different spectral characteristics than non-lucid REMS, it is fair to say that there is substantial disagreement with regard to the brain regions and EEG frequency bands most activated during lucid dreams…

Read the full article here NEIP (pdf)