Critical-like Brain Dynamics in a Continuum from Second- to First-Order Phase Transition

Area of Science:

• Neuroscience
• Complex Systems
• Computational Psychiatry

Background:

• The brain criticality hypothesis suggests optimal function near a second-order phase transition.
• Neuronal feedback may induce first-order transitions and bistability, but empirical evidence is scarce.
• The human brain's capacity to operate across a continuum of phase transitions remains unproven.

Purpose of the Study:

• To investigate bistable synchronization dynamics in critical-like brain activity.
• To empirically assess neuronal bistability in vivo using MEG and SEEG.
• To explore the functional significance of bistability in healthy and patient populations.

Main Methods:

• Computational modeling to simulate bistable synchronization dynamics.
• Resting-state magnetoencephalography (MEG) in healthy adults.
• Stereo-electroencephalography (SEEG) in epilepsy patients.

Main Results:

• Bistable synchronization emerged in computational models with elevated positive feedback within critical-like dynamics.
• Neuronal bistability was widespread across human neocortices (3-200 Hz) and correlated with brain criticality.
• Moderate bistability linked to better task performance in healthy individuals; excessive bistability predicted epileptic pathophysiology.

Conclusions:

• The human brain exhibits critical-like dynamics across a continuum of phase transitions, from continuous to discontinuous.
• Neuronal bistability is a pervasive feature of brain activity, dependent on frequency, neuroanatomy, and state.
• Bistability plays a functional role, with implications for cognition and neurological disorders.