Pathological High-Frequency Oscillations in Mesial Temporal Lobe Epilepsy

Abstract

Recent technological advances in signal acquisition and analysis have led to the discovery of high-frequency oscillatory events in animal models of mesial temporal lobe epilepsy (MTLE) and in the EEG of epileptic patients. These high-frequency oscillations (HFOs) in the 80–500 Hz frequency range are thought to reflect the activity of dysfunctional neuronal networks that may sustain epileptogenesis and ictogenesis. In this chapter, we review recent findings on HFOs in MTLE and their contribution to the identification of the pathophysiological mechanisms underlying the development of this epileptic condition. We describe the presumptive cellular and network mechanisms underlying ripples (80–200 Hz) and fast ripples (250–500 Hz) as well as their relation with interictal spikes and seizures. In addition, we discuss their contribution to epileptogenesis and ictogenesis in epileptic patients and animal models of MTLE.