A novel method for dynamically altering the surface area of intracranial EEG electrodes

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Technology

Background:

• Intracranial electroencephalogram (iEEG) is vital for treating neurological disorders and developing brain-computer interfaces.
• The effect of electrode size on iEEG signal characteristics is not fully understood.
• Existing methods for comparing different electrode sizes involve separate brain locations or simulations.

Purpose of the Study:

• To develop and validate a novel method for recording iEEG from multiple electrode sizes at the identical brain location.
• To investigate the impact of electrode size on iEEG signal features and morphology in humans.

Main Methods:

• A theoretical model and in vitro validation of a post-implantation electrode size adjustment technique.
• In vivo implementation in three human subjects with refractory epilepsy.
• Comparison of iEEG amplitude, power spectra, inter-channel correlation, and signal-to-noise ratio (SNR) for different electrode sizes.

Main Results:

• iEEG amplitude and power decreased with increasing electrode size.
• Inter-channel correlation remained largely unchanged across different electrode sizes.
• Signal-to-noise ratio (SNR) of epileptic spikes was typically highest in smaller electrodes, but varied depending on spike characteristics.

Conclusions:

• The novel method allows for multi-scale electrical recordings from the human brain.
• This technique can enhance understanding of neurophysiology and aid in developing treatments for neurological diseases.
• Findings provide crucial data for optimizing electrode design in neural prosthetics and brain-computer interfaces.