Classification of cortico-cortical evoked potential waveforms and their implications for brain anatomy

Area of Science:

• Neuroscience
• Epilepsy Research
• Brain Connectivity

Background:

• Cortico-cortical evoked potential (CCEP) waveforms commonly present with early (N1) and late (N2) negative peaks.
• Understanding CCEP waveform variations is crucial for interpreting brain activity and connectivity.

Purpose of the Study:

• To classify CCEP waveform morphologies.
• To investigate the anatomical distribution of different CCEP waveform types.
• To establish a neurophysiological framework for CCEP interpretation.

Main Methods:

• CCEP waveforms were categorized into five types based on N1 peak latency and morphology (Types I-V).
• A total of 7928 CCEP waveforms from ten epilepsy patients were analyzed.
• Manual review assessed waveform morphology and anatomical distribution.

Main Results:

• Type I CCEPs (typical N1 latency) constituted 49.8% and were near superior longitudinal fasciculus terminals.
• Types II and III (delayed N1) comprised 43.2% and were located on the interhemispheric surface and dorsal parietal regions.
• Type IV (positive/inverted) responses appeared in postero-inferior lateral and temporal basal areas.

Conclusions:

• Approximately half of CCEPs displayed typical N1 and N2 responses, with significant morphological variations observed.
• The developed classification framework connects CCEP morphology to white-matter pathways and cortical properties.
• This framework supports the use of CCEP features as biomarkers for intraoperative functional network monitoring.