Chapter

Normal and Pathological High-Frequency Oscillations

Richard J. Staba

in Jasper's Basic Mechanisms of the Epilepsies

Fourth edition

Published on behalf of ©Jeffrey L. Noebels, Massimo Avoli, Michael A. Rogawski, Richard W. Olsen, and Antonio V. Delgado-Escueta

Published in print July 2012 | ISBN: 9780199746545
Published online April 2013 | e-ISBN: 9780199322817 | DOI: http://dx.doi.org/10.1093/med/9780199746545.003.0016

Series: Contemporary Neurology Series

Normal and Pathological High-Frequency Oscillations

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During natural waking and sleep behavior, the occurrence of spontaneous rhythmic field potentials, for example theta (3–8 Hz), gamma (30–80 Hz), and high-frequency oscillations (HFOs; 80–600 Hz), correspond with an increase in the rate and synchrony of neuronal firing. Compared to theta and gamma oscillations, networks supporting the generation of HFOs can be smaller in size and events shorter in duration, but the increase in neuronal firing and synchrony of discharges that occurs on a temporal scale of a few milliseconds or less can be much greater. Because HFOs can facilitate synaptic transmission through local networks, these events are implicated in information processing and consolidation of memory. Alterations to neuronal networks associated with epilepsy can also generate abnormal or pathological HFOs (pHFOs) that are believed to reflect fundamental neuronal disturbances associated with brain areas capable of generating spontaneous epileptic seizures. However, distinguishing normal HFOs from pHFOs is not always simple, particularly in studies involving intracranial brain recordings in presurgical patients with medically refractory epilepsy. This chapter will describe some of the spatial and temporal properties of HFOs observed in normal and epileptic mammalian brain and roles HFOs could play in normal brain function and epilepsy. Important to any description of HFOs are the putative mechanisms that support the generation of normal HFOs and pHFOs, and how pHFOs could be clinically useful in the treatment of epilepsy.

Chapter.  6650 words.  Illustrated.

Subjects: Neurology

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