Dynamic local connectivity uncovers altered brain synchrony during propofol sedation

Area of Science:

• Neuroscience
• Cognitive Science
• Medical Imaging

Background:

• Human consciousness is theorized to emerge from synchronized activity across multiple dynamic brain networks.
• Understanding how consciousness is altered by external agents like anesthetics is crucial for neuroscience and clinical practice.

Purpose of the Study:

• To characterize sedation-induced alterations in brain network dynamics using functional magnetic resonance imaging (fMRI).
• To investigate changes in functional connectivity during propofol-induced sedation.

Main Methods:

• Dynamic functional connectivity analysis was performed on resting-state fMRI (rsfMRI) data from 14 patients before and during propofol infusion.
• A sliding window approach (36 seconds) generated 59 time points of whole-brain connectivity measurements.
• Connectivity strength fluctuations (Z Corr) were analyzed to compare awake and sedated states.

Main Results:

• Sedation significantly reduced cortical connectivity fluctuations in default mode network (DMN) and perirolandic regions.
• A decreased correlation of connectivity between anatomical homologues was observed during sedation.
• Increased connectivity fluctuations were noted in subcortical regions (cerebellum, thalamus, basal ganglia, insula) within a specific frequency range (0.027–0.063 Hz).

Conclusions:

• Sedation dynamically alters brain network integration, affecting both cortical and subcortical regions.
• Findings support the view of consciousness as an emergent property of dynamic, integrated brain networks.
• This research provides novel insights into the neural mechanisms underlying altered states of consciousness.