Data mining neocortical high-frequency oscillations in epilepsy and controls.

Published

Journal Article

Transient high-frequency (100-500 Hz) oscillations of the local field potential have been studied extensively in human mesial temporal lobe. Previous studies report that both ripple (100-250 Hz) and fast ripple (250-500 Hz) oscillations are increased in the seizure-onset zone of patients with mesial temporal lobe epilepsy. Comparatively little is known, however, about their spatial distribution with respect to seizure-onset zone in neocortical epilepsy, or their prevalence in normal brain. We present a quantitative analysis of high-frequency oscillations and their rates of occurrence in a group of nine patients with neocortical epilepsy and two control patients with no history of seizures. Oscillations were automatically detected and classified using an unsupervised approach in a data set of unprecedented volume in epilepsy research, over 12 terabytes of continuous long-term micro- and macro-electrode intracranial recordings, without human preprocessing, enabling selection-bias-free estimates of oscillation rates. There are three main results: (i) a cluster of ripple frequency oscillations with median spectral centroid = 137 Hz is increased in the seizure-onset zone more frequently than a cluster of fast ripple frequency oscillations (median spectral centroid = 305 Hz); (ii) we found no difference in the rates of high frequency oscillations in control neocortex and the non-seizure-onset zone neocortex of patients with epilepsy, despite the possibility of different underlying mechanisms of generation; and (iii) while previous studies have demonstrated that oscillations recorded by parenchyma-penetrating micro-electrodes have higher peak 100-500 Hz frequencies than penetrating macro-electrodes, this was not found for the epipial electrodes used here to record from the neocortical surface. We conclude that the relative rate of ripple frequency oscillations is a potential biomarker for epileptic neocortex, but that larger prospective studies correlating high-frequency oscillations rates with seizure-onset zone, resected tissue and surgical outcome are required to determine the true predictive value.

Full Text

Duke Authors

Cited Authors

  • Blanco, JA; Stead, M; Krieger, A; Stacey, W; Maus, D; Marsh, E; Viventi, J; Lee, KH; Marsh, R; Litt, B; Worrell, GA

Published Date

  • October 2011

Published In

Volume / Issue

  • 134 / Pt 10

Start / End Page

  • 2948 - 2959

PubMed ID

  • 21903727

Pubmed Central ID

  • 21903727

Electronic International Standard Serial Number (EISSN)

  • 1460-2156

International Standard Serial Number (ISSN)

  • 0006-8950

Digital Object Identifier (DOI)

  • 10.1093/brain/awr212

Language

  • eng