Microscale dynamics of electrophysiological markers of epilepsy.

Abstract Objective Interictal discharges (IIDs) and high frequency oscillations (HFOs) are established neurophysiologic biomarkers of epilepsy, while microseizures are less well studied. We used custom poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) microelectrodes to better understand these markers’ microscale spatial dynamics. Methods Electrodes with spatial resolution down to 50 µm were used to record intraoperatively in 30 subjects. IIDs’ degree of spread and spatiotemporal paths were generated by peak-tracking followed by clustering. Repeating HFO patterns were delineated by clustering similar time windows. Multi-unit activity (MUA) was analyzed in relation to IID and HFO timing. Results We detected IIDs encompassing the entire array in 93% of subjects, while localized IIDs, observed across  Conclusions Overall, these data suggest that irritable cortex micro-domains may form part of an underlying pathologic architecture which could contribute to the seizure network. Significance These results, supporting the possibility that epileptogenic cortex comprises a mosaic of irritable domains, suggests that microscale approaches might be an important perspective in devising novel seizure control therapies.