Topographic Movie of Ictal High-Frequency Oscillations on the Brain Surface Using Subdural EEG in Neocortical Epilepsy

Recent studies show that the brain gamma activity includes both the gamma rhythm (standard EEG) and high frequency (100-1000 Hz) as well as super-high (>1000 Hz) frequency oscillations, as recorded by electrocorticography. As reported in the literature, the high-frequency oscillations (80-500 Hz) are highly informative markers of an epileptic focus. In this review, we analyze features of high-frequency activity associated with the epileptiform activity, and its relation to the seizure onset range. Further study of high-frequency bioelectric activity of the brain is of interest to researchers and clinicians, and may improve the EEG differential diagnosis of epilepsy.

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High-Frequency EEG Activity

10.1093/med/9780190228484.003.0033 ◽

2017 ◽

Author(s):

Jean Gotman ◽

Nathan E. Crone

Keyword(s):

Clinical Significance ◽

High Frequency ◽

Brain Regions ◽

Eeg Activity ◽

Work Related ◽

High Frequency Oscillations ◽

Sensory Motor ◽

The Brain ◽

Important Marker

Activities with frequencies between 60 and 80 Hz and approximately 500 Hz are labeled here as high-frequency activities. They were largely ignored until the beginning of the millennium, but their importance is now well recognized. They can be divided into activities occurring in the healthy brain in relation to sensory, motor, and cognitive or memory activity and activities occurring in the epileptic brain in the form of brief events (high-frequency oscillations), which appear to be an important marker of the brain regions that are able to generate seizures of focal origin. In humans, most of the work related to these activities has been done in intracerebral electrodes, where they are relatively frequent and easy to identify. They have been recorded in scalp electroencephalograms in some circumstances, however. This chapter reviews the recording methods, the circumstances in which they occur, their mechanism of generation, and their clinical significance.

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Synchronized Spikes of Thalamocortical Axonal Terminals and Cortical Neurons Are Detectable Outside the Pig Brain With MEG

Journal of Neurophysiology ◽

10.1152/jn.00332.2001 ◽

2002 ◽

Vol 87 (1) ◽

pp. 626-630 ◽

Cited By ~ 73

Author(s):

Hiroaki Ikeda ◽

Leonard Leyba ◽

Anton Bartolo ◽

Yaozhi Wang ◽

Yoshio C. Okada

Keyword(s):

Electrical Stimulation ◽

High Frequency ◽

Cortical Neurons ◽

Kynurenic Acid ◽

Cortical Layer ◽

Projection Area ◽

High Frequency Oscillations ◽

Highly Correlated ◽

The Brain ◽

Stimulation Of

We show that it is feasible to monitor the synchronized population spikes of the thalamocortical axonal terminals and cortical neurons outside the brain using high-resolution magnetoencephalography (MEG). Electrical stimulation of the snout elicited somatic-evoked magnetic fields (SEFs) above the primary somatosensory cortex (SI) of the piglet. The SEFs contained high-frequency oscillations (HFOs) around 600 Hz similar in many respects to the noninvasively measured HFOs from humans with MEG and electroencephalography (EEG). These HFOs were highly correlated with those in simultaneously measured intracortical somatic-evoked potentials (SEPs) in the snout projection area in SI. Both HFOs in SEFs and SEPs consisted of an initial component insensitive to cortically injected kynurenic acid (Kyna, 20 mM), a nonspecific antagonist of glutamatergic receptors, and a subsequent Kyna-sensitive component. The former was localized in cortical layer IV, indicating that it was due to spikes produced by the specific thalamocortical axonal terminals, whereas the latter was initially localized in layer IV and subsequently in the superficial and deeper layers. These results suggest that it may be possible to study properties of the thalamocortical and cortical spike activities in humans with MEG.

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High-frequency oscillations and seizure generation in neocortical epilepsy

Brain ◽

10.1093/brain/awh149 ◽

2004 ◽

Vol 127 (7) ◽

pp. 1496-1506 ◽

Cited By ~ 344

Author(s):

G. A. Worrell ◽

L. Parish ◽

S. D. Cranstoun ◽

R. Jonas ◽

G. Baltuch ◽

...

Keyword(s):

High Frequency ◽

High Frequency Oscillations ◽

Neocortical Epilepsy

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Ictal high-frequency oscillations in neocortical epilepsy: implications for seizure localization and surgical resection

Epilepsia ◽

10.1111/j.1528-1167.2011.03165.x ◽

2011 ◽

Vol 52 (10) ◽

pp. 1792-1801 ◽

Cited By ~ 70

Author(s):

Pradeep N. Modur ◽

Song Zhang ◽

Todd W. Vitaz

Keyword(s):

Surgical Resection ◽

High Frequency ◽

High Frequency Oscillations ◽

Neocortical Epilepsy ◽

Seizure Localization

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High-frequency oscillations and gamma activity in the diagnosis of epilepsy

Medical alphabet ◽

10.33667/2078-5631-2019-2-12(387)-9-12 ◽

2019 ◽

Vol 2 (12) ◽

pp. 9-12

Author(s):

G. V. Selitsky ◽

S. S. Pertsov ◽

N. D. Sorokina

Keyword(s):

Differential Diagnosis ◽

High Frequency ◽

Gamma Activity ◽

Epileptic Focus ◽

Bioelectric Activity ◽

High Frequency Oscillations ◽

Gamma Rhythm ◽

The Brain

Modern studies of gamma rhythm indicate that gamma activity (30–80 Hz in standard EEG), and high-frequency (80–1000 Hz) and ultra-frequency oscillations (more than 1000 Hz), recorded by ECOG, are highly informative markers of epileptic focus. Further study of high-frequency bioelectric activity of the brain is of interest to researchers and clinicians in order to improve the electroencephalographic differential diagnosis in epilepsy.

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