Quantitative Analysis of High-Frequency Oscillations (80–500 Hz) Recorded in Human Epileptic Hippocampus and Entorhinal Cortex

High-frequency oscillations (100-200 Hz), termed ripples, have been identified in hippocampal (Hip) and entorhinal cortical (EC) areas of rodents and humans. In contrast, higher-frequency oscillations (250-500 Hz), termed fast ripples (FR), have been described in seizure-generating limbic areas of rodents made epileptic by intrahippocampal injection of kainic acid and observed in humans ipsilateral to areas of seizure initiation. However, quantitative studies supporting the existence of two spectrally distinct oscillatory events have not been carried out in humans nor has the preferential appearance of FR within seizure generating areas received statistical evaluation based on analysis of a large sample of…