Sub-second fluctuations between top-down and bottom-up modes distinguish diverse human brain states

Area of Science:

• Neuroscience
• Computational Neuroscience
• Cognitive Neuroscience

Background:

• Brain activity involves continuous information flow across regions, shifting with consciousness and cognitive states.
• Current methods like fMRI capture slow, large-scale changes, leaving sub-second dynamics poorly understood.

Purpose of the Study:

• Introduce relative phase analysis (RPA) for real-time, millisecond-precision whole-brain dynamics from electroencephalography (EEG).
• Investigate sub-second alternations in brain information flow and their relation to consciousness and neuropsychiatric conditions.

Main Methods:

• Applied relative phase analysis (RPA) to electroencephalography (EEG) data for millisecond-precision analysis.
• Utilized simultaneous EEG-fMRI recordings to correlate dynamics with network activity.
• Employed a connectome-based coupled-oscillator model to simulate brain dynamics.

Main Results:

• Identified approximately 200 ms alternations between top-down (anterior-to-posterior) and bottom-up (posterior-to-anterior) information flow modes.
• Observed diminished dynamics under anesthesia and pathological imbalance in attention-deficit/hyperactivity disorder (ADHD).
• Linked top-down dynamics to higher-order cognitive networks and bottom-up dynamics to sensory networks via EEG-fMRI.

Conclusions:

• Relative phase analysis (RPA) provides a framework for real-time tracking of whole-brain dynamics.
• Sub-second top-down/bottom-up alternations represent a fundamental principle of human brain function and consciousness.
• These dynamics are sensitive to states of consciousness and neurological conditions like ADHD.