Precaution for volume conduction in rodent cortical electroencephalography using high-density polyimide-based...

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• Human electroencephalography (EEG) studies benefit from high spatial resolution, linking brain activity to various correlates.
• Standard rodent EEG methods offer limited spatial resolution due to few electrodes.
• A polyimide-based microelectrode (PBM) array advanced mouse EEG spatial resolution.

Purpose of the Study:

• To adapt and evaluate a high-density polyimide-based microelectrode (PBM) array for electroencephalography (EEG) recording in rats.
• To assess the utility and validity of the rat PBM array by examining signal synchrony and volume conduction effects.
• To enable untethered, freely moving rat EEG recordings using a wireless headstage.

Main Methods:

• Designed and fabricated a rat-adapted PBM array for skull application.
• Connected the PBM array to a wireless EEG headstage for untethered recordings.
• Evaluated signal synchrony between channels under basal and ketamine-induced states to differentiate true synchrony from volume conduction.

Main Results:

• The PBM array enabled high-quality EEG recordings in freely moving rats.
• Significant signal synchronization due to volume conduction was observed across electrode pairs, even at higher frequencies.
• Spatial discrimination of signals was limited to distinctions between frontal and central/distal electrode groups.

Conclusions:

• While the PBM array offers high signal quality and potential for improved spatial resolution in rat EEG, volume conduction significantly impacts signal interpretation.
• Researchers must exercise caution when interpreting spatial EEG data derived from high-density PBM arrays in rodents.
• Further research may be needed to refine techniques for isolating localized brain activity from volume-conducted signals in rodent EEG.