Evoked Alpha Power is Reduced in Disconnected Consciousness During Sleep and Anesthesia
Matthieu Darracq, Chadd M. Funk, Daniel Polyakov, Brady A. Riedner, Olivia Gosseries, Jaakko O. Nieminen, Vincent Bonhomme, J. F. Brichant, Melanie Boly, Steven Laureys, Giulio Tononi, Robert D. Sanders
Scientific Reports November 5, 2018 DOI: 10.1038/s41598-018-34957-9 via OpenAlex
Summary
Sleep and anesthesia alter conscious experience, which can be absent (unconsciousness) or take the form of dreaming where sensory stimuli are not incorporated (disconnected consciousness). Using transcranial magnetic stimulation-electroencephalography over parietal regions, evoked alpha power (8-12 Hz) decreased during disconnected consciousness in rapid eye movement sleep and ketamine anesthesia compared to wakefulness. In unconscious states of propofol anesthesia and non-rapid eye movement sleep, evoked low-gamma power (30-40 Hz) decreased compared to wakefulness or disconnected consciousness. These findings, confirmed with dream reports from serial awakenings, suggest suppression of evoked alpha activity may mark sensory disconnection.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Keywords | Wakefulness Unconsciousness Electroencephalography Psychology Neuroscience |
| Citations | 49 |
| Key finding | Evoked alpha power is decreased during disconnected consciousness compared to wakefulness, while evoked low-gamma power is decreased in unconscious states compared to wakefulness or disconnected consciousness. |
Abstract
Sleep and anesthesia entail alterations in conscious experience. Conscious experience may be absent (unconsciousness) or take the form of dreaming, a state in which sensory stimuli are not incorporated into conscious experience (disconnected consciousness). Recent work has identified features of cortical activity that distinguish conscious from unconscious states; however, less is known about how cortical activity differs between disconnected states and normal wakefulness. We employed transcranial magnetic stimulation-electroencephalography (TMS-EEG) over parietal regions across states of anesthesia and sleep to assess whether evoked oscillatory activity differed in disconnected states. We hypothesized that alpha activity, which may regulate perception of sensory stimuli, is altered in the disconnected states of rapid eye movement (REM) sleep and ketamine anesthesia. Compared to wakefulness, evoked alpha power (8-12 Hz) was decreased during disconnected consciousness. In contrast, in unconscious states of propofol anesthesia and non-REM (NREM) sleep, evoked low-gamma power (30-40 Hz) was decreased compared to wakefulness or states of disconnected consciousness. These findings were confirmed in subjects in which dream reports were obtained following serial awakenings from NREM sleep. By examining signatures of evoked cortical activity across conscious states, we identified novel evidence that suppression of evoked alpha activity may represent a promising marker of sensory disconnection.