Intracranial EEG referencing for large-scale category-selective mapping in the human ventral occipito-temporal cortex

Area of Science:

• Cognitive Neuroscience
• Neurophysiology
• Electrophysiology

Background:

• Intracranial EEG (iEEG) provides high-resolution brain activity data in humans.
• The influence of reference montage choice on iEEG data characteristics is not well understood.

Purpose of the Study:

• To compare the spatial and temporal profiles of iEEG activity across five common reference montages.
• To investigate the impact of reference montages on face-selective neural activity in the ventral occipito-temporal cortex (VOTC).

Main Methods:

• Analysis of StereoElectroEncephaloGraphy (SEEG) recordings from 77 human brains.
• Comparison of five reference montages: scalp, common average, zero, local bipolar, and Laplacian.
• Utilized frequency-tagging to quantify low- (<30 Hz) and high-frequency (40-160 Hz) neural activity.

Main Results:

• Low-frequency responses showed similar spatial and temporal patterns across montages, with local montages enhancing face selectivity but reducing hemispheric dominance.
• High-frequency responses were largely consistent, except for the scalp reference, which improved selectivity in some areas but increased white matter signal.
• All montages showed some increase in white matter contacts with local references or scalp reference.

Conclusions:

• Reference montage selection critically influences iEEG data interpretation.
• Consider the research question, anatomy, analysis type, and frequency range when choosing an iEEG reference montage.