Cortical functional connectivity indexes arousal state during sleep and anesthesia

Area of Science:

• Neuroscience
• Cognitive Science
• Sleep Research

Background:

• Disruption of cortical connectivity is implicated in loss of consciousness (LOC) during sleep and general anesthesia.
• The overlap in underlying mechanisms between sleep-induced and anesthesia-induced LOC remains unclear.
• Both sleep and anesthesia involve varying levels of arousal and consciousness.

Purpose of the Study:

• To test if cortical connectivity changes distinctly during transitions to reduced consciousness states.
• To determine if these connectivity changes are similar for comparable consciousness levels in sleep and anesthesia.
• To investigate functional connectivity as a potential biomarker for arousal states.

Main Methods:

• Intracranial recordings from five adult neurosurgical patients.
• Comparison of resting state cortical functional connectivity (weighted phase lag index, wPLI) in alpha-band.
• Analysis across natural sleep states (wake, N1, N2, N3, REM) and propofol anesthesia (wake, sedated/responsive, unresponsive).

Main Results:

• A transition boundary in alpha-band connectivity distinguished maintained from reduced conscious experience in both sleep and anesthesia.
• Dominant temporal lobe connectivity in wake states shifted to prefrontal cortex in reduced consciousness states (N2, N3, unresponsive).
• Similar reorganization patterns of cortical connectivity were observed between sleep and anesthesia.

Conclusions:

• Shifts in cortical connectivity, from temporal to frontal, may indicate impaired sensory processing in reduced consciousness.
• Functional connectivity serves as a biomarker for arousal state.
• Common mechanisms underlie loss of consciousness during both natural sleep and general anesthesia.