High-frequency oscillations in human brain

TLDR

Ripples are 100–200 Hz short‑duration oscillatory field potentials recorded in rat hippocampus and entorhinal cortex, reflecting fast IPSPs on pyramidal cell somas during synchronous afferent excitation of principal cells and interneuron networks. The study aims to describe two similar types of high‑frequency field oscillations recorded from the entorhinal cortex and hippocampus of patients with mesial temporal lobe epilepsy. The authors recorded these oscillations in the entorhinal cortex and hippocampus of mesial temporal lobe epilepsy patients, identifying two distinct high‑frequency patterns. The first type corresponds to the human equivalent of normal ripples, while the second, fast ripples (250–500 Hz), are found in the epileptogenic region and may reflect pathological hypersynchronous population spikes of bursting pyramidal cells. © 1999 Wiley‑Liss, Inc.; Hippocampus 1999;9:137–142.

Abstract

Ripples are 100–200 Hz short-duration oscillatory field potentials that have recently been recorded in rat hippocampus and entorhinal cortex. They reflect fast IPSPs on the soma of pyramidal cells, which occur during synchronous afferent excitation of principal cells and interneuron networks. We now describe two similar types of high-frequency field oscillations recorded from the entorhinal cortex and hippocampus of patients with mesial temporal lobe epilepsy. The first type appears be the human equivalent of normal ripples in the rat. The second, which we have termed fast ripples (FR), are in the frequency range of 250–500 Hz. FR are found in the epileptogenic region and may reflect pathological hypersynchronous population spikes of bursting pyramidal cells. Hippocampus 1999;9:137–142. © 1999 Wiley-Liss, Inc.