Alpha-band activity is the most prominent neurobiological feature of scalp electroencephalography (EEG) signals, recent findings showed that there is more than one alpha rhythm coexisted in this 8-13 Hz band, but the generation mechanism of them was not fully understood. To address this question, we collected local field potential (LFP) in 32 brain regions of human brain with stereo-EEG (SEEG), with simultaneously recording with EEG during the process from awaked state (eyes-closed) to loss of consciousness (LOC) state with anesthesia. Our study revealed a prominent low-alpha (LA) rhythm (8-10 Hz) localized in the occipital region during the awake, eyes-closed state. As anesthetic depth increased leading to the LOC, this low-alpha rhythm gradually diminished and was replaced by a globally distributed high-alpha (HA) rhythm (10-13 Hz). This phenomenon was consistently observed at both LFP and EEG levels. Furthermore, we demonstrated that state-dependent changes of oscillatory property in alpha band were primarily driven by periodic rather than aperiodic activities, which could be also effectively explained by a simple dynamical model. This work provides the first evidence of anesthetic-induced modulation mechanisms underlying the generation and regulation of distinct alpha oscillations, offering valuable insights for future research in anesthesia, consciousness studies, and potential clinical applications. SEEG and EEG data reveal a transition from occipital low-alpha (8-10 Hz) to global high-alpha (10-13 Hz) during anesthesia-induced loss of consciousness. Periodic shifts, modeled dynamically, clarify distinct mechanisms for alpha band regulation.
Wang et al. (Mon,) studied this question.