Metastable oscillatory modes emerge from synchronization in the brain spacetime connectome

Area of Science:

• Neuroscience
• Computational Physics
• Network Science

Background:

• Human brain activity exhibits diverse oscillatory signals detected via electro- and magnetoencephalography (EEG/MEG).
• The underlying mechanisms of coherent brain oscillations and their relationship to neural activity are not fully understood.
• Existing hypotheses suggest transient brain rhythms may arise from metastable synchronization.

Purpose of the Study:

• To investigate the hypothesis that transient brain rhythms are a signature of metastable synchronization.
• To explore how delays between brain areas influence collective oscillation frequencies.
• To model the emergence of brain rhythms using principles of physics.

Main Methods:

• A system of damped oscillators was simulated, incorporating background noise to mimic gamma-frequency oscillations.
• Oscillators were coupled based on diffusion-weighted tractography data representing brain connectivity.
• Global coupling strength and conduction speed were systematically varied to observe emergent phenomena.

Main Results:

• A critical regime was identified where metastable oscillatory modes (MOMs) emerged at sub-gamma frequencies.
• These simulated MOMs closely approximated resting-state magnetoencephalography (MEG) power spectra from 89 healthy individuals.
• Key characteristics of MOMs, including frequency, duration, scale, and functional connectivity, were controllable via global parameters without altering the connectome structure.

Conclusions:

• The study demonstrates that interactions within the connectome's spacetime structure can generate collective brain rhythms.
• Metastable synchronization, influenced by network delays, provides a mechanistic explanation for observed brain oscillations.
• This physics-based modeling approach offers insights into the organization of brain activity in space and time.