Global field synchrony during general anaesthesia.

Area of Science:

• Neuroscience
• Anesthesiology
• Signal Processing

Background:

• Anesthetic agents are known to disrupt consciousness by interfering with long-range brain activity synchronization.
• Investigating widespread and localized brain synchrony patterns during anesthesia is crucial for understanding its effects on consciousness.

Purpose of the Study:

• To investigate the patterns of widespread and spatially localized brain synchrony during anesthesia using global field synchrony (GFS).
• To identify specific frequency bands and brain regions where GFS changes are most pronounced under anesthesia.

Main Methods:

• Electroencephalography (EEG) data from 29 patients undergoing routine surgery were analyzed using GFS.
• GFS was calculated across multiple frequency bands (δ, θ, α1, α2, β1, β2, β3, γ1, γ2) and localized brain areas.
• Statistical analysis (Wilcoxon rank-sum tests) compared GFS values between wakefulness and anesthesia states.

Main Results:

• Anesthetic administration significantly altered GFS in all studied frequency ranges and electrode combinations.
• Widespread synchrony increased in α2 and β1 bands, while decreasing in most other bands.
• Localized synchrony decreased across all areas in the δ and γ2 bands, with notable changes in the central-right temporal region.

Conclusions:

• Anesthesia induces significant frequency- and location-dependent changes in GFS, particularly evident in the gamma frequency range.
• GFS analysis provides a valuable tool for detailed investigation into how specific frequency and spatial brain activity patterns relate to anesthetic-induced unconsciousness.