In vivo interictal signatures of human periventricular nodular heterotopia

ABSTRACT Periventricular nodular heterotopia (PNH) causes drug-resistant epilepsy. We analyzed in vivo interictal activities from three nodules of two epileptic patients using macro-microelectrodes. Two highly unusual interictal LFP patterns (IPs) were identified: Trains of periodic slow waves and isolated slow deflections, both with superimposed fast activity. These patterns were restricted to the nodules, and largely invisible on adjacent macroelectrodes. Neuron firing rates were significantly modulated during all IPs, suggesting that similar or overlapping neuronal populations generate different IPs. This study presents the first in vivo multi-level evidence of local PNH networks in humans and their organization into multiple interictal events.