EEG dynamics. Brain processing of sensory and cognitive information

Area of Science:

• Neuroscience
• Biophysics
• Signal Processing

Background:

• Electroencephalography (EEG) signals exhibit variability in frequency and amplitude before sensory input.
• Pre-stimulus EEG demonstrates low time-coherency and random phase angles between brain structures.
• This inherent instability suggests a lack of synchronized neural network activity prior to stimulation.

Purpose of the Study:

• To investigate the dynamic changes in EEG oscillations and coherence following sensory stimulation.
• To explore the relationship between neural oscillator coupling, resonance phenomena, and EEG signal characteristics.
• To elucidate the transition of brain activity from an incoherent to a coherent state post-stimulus.

Main Methods:

• Analysis of EEG recordings from various brain structures.
• Examination of EEG frequency, amplitude, time-coherency, and phase angle dynamics.
• Assessment of inter-brain structure coherence and internal evoked potentials before and after sensory stimulation.

Main Results:

• Sensory stimulation led to stabilized EEG frequencies and significantly enhanced amplitudes.
• A shift towards time-coherency and high inter-brain structure coherence was observed post-stimulation.
• Zero-phase angles were detected in brain rhythm channels across structures, indicating synchronized activity.
• Internal evoked potentials were present in all studied brain nuclei, with frequencies dependent on pre-stimulus EEG.

Conclusions:

• Sensory stimulation induces a transition to a synchronized, coherent brain state.
• The observed EEG changes are linked to the coupling of neural oscillators and resonance phenomena.
• Post-stimulus brain activity reflects synchronized harmonic oscillators and enhanced neural communication.