Power-law scaling in the brain surface electric potential

Area of Science:

• Neuroscience
• Computational Neuroscience
• Signal Processing

Background:

• Recent studies indicate broadband phenomena in brain electric potentials.
• Understanding the underlying mechanisms of these broadband signals is crucial for advancing neuroscience.

Purpose of the Study:

• To investigate power-law scaling in human cortical electric potentials.
• To characterize the scaling index and its conservation across different conditions.
• To explore the implications for understanding brain activity paradigms.

Main Methods:

• Utilized subdural electrocorticographic (ECoG) recordings from the human cortex surface.
• Analyzed the power spectral density (PSD) of electric potentials in the 80-500 Hz range.
• Employed simulations of simplified neuronal models to explain observed phenomena.

Main Results:

• Identified power-law scaling in the PSD with a conserved scaling index (chi = 4.0+/-0.1) across subjects and cortical areas.
• Observed that the PSD shape remains constant with increasing neural activity, while amplitude increases.
• Detected a spectral "knee" around 75 Hz, suggesting a characteristic time scale of 2-4 ms.

Conclusions:

• Cortical electric potentials exhibit scale-free, asynchronous activity, complementing existing synchronous, rhythm-based models.
• The findings suggest that power-law scaling is a fundamental property of cortical dynamics.
• Simplified neuronal models can reproduce these observed power-law characteristics.