Temporal changes in resting state networks induced by propofol anesthesia.

The cerebral cortical changes associated with propofol-induced unconsciousness remain unknown. While the anesthetic agent affects the entire cerebral cortices, there might be spatiotemporal differences in cortical changes. In particular, we hypothesized that there might be spatiotemporal differences in cortical changes with propofol-anesthesia. To address this hypothesis, we investigated power spectrum changes in electrocorticography (ECoG) signals obtained during the induction phase from awake state to unconsciousness. We found that, 1) the power increased in the range of frequencies < 46 Hz (delta to low gamma), and decreased in the range (62-150) Hz (high gamma), in global channels during the induction phase. 2) The power in the frontoparietal network (FPN), specifically the superior parietal lobule and prefrontal cortex, started to change early, but took a long time to completely change. However, the power in the default mode network (DMN) started to change late, but took a short time to completely change. 3) The power change ({Delta}Power) in the DMN was more conspicuous than that of the dorsal attention network (DAN) in high gamma frequency. Considering that the FPN is involved in communication with the external world and that DMN is involved in communication with self, loss of consciousness induced by general anesthesia results from first, disrupted communication between self and external world, and is then followed by disrupted communication within self, with decreased activity of the FPN, and later, attenuated activity of the DMN. Significance StatementWe investigated the spatiotemporal changes of power spectrum in human electrocorticography (ECoG) during the induction phase from awake state to unconsciousness. We found that from delta to low gamma frequency, the power increased, while in high gamma frequency, the power decreased over all channels. The power in the frontoparietal network (FPN) preferentially changed, then the power in the DMN changed later. The power in DMN decreased more than those in other RSNs in high gamma frequency. Loss of consciousness induced by general anesthesia results from first, disrupted communication between self and external world, followed by disrupted communication within self, with decreased activity of the FPN, and later, attenuated activity of the DMN.