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   -> Volume 11, Issue 1

Preprint: EEG time-frequency analysis during epileptic seizures
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Rodrigo Quian Quiroga (

PostPosted: Wed Jan 02, 2002 4:32 pm    
Subject: Preprint: EEG time-frequency analysis during epileptic seizures
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Title: Frequency evolution during tonic-clonic seizures.

Authors: R. Quian Quiroga, H. Garcia and A. Rabinowicz.

Jornal: Electromyography and Clinical Neurophyisiology, in press.

Abstract: By using the Short Time Fourier Transform, we analyzed the EEG frequency evolution during tonic-clonic seizures on 18 scalp recordings corresponding to 7 patients admitted for Video-EEG monitoring. This information was correlated with clinical findings observed in the video recordings. From the time-frequency plots, we recognized patterns related with brain activity even when embedded in a background of muscle artifacts. In 13/18 seizures we found a clear frequency dynamics characterized by an activity originally localized at about 8 Hz, later slowing down to about 1.5Hz. In the remaining cases muscle artifacts hinder the disclosure of a clear frequency evolution. The clonic phases started when the main frequency slowed down to about 3Hz. We conclude that the Short Time Fourier Transform is very useful for a quantitative analysis of epileptic seizures, especially when muscle artifacts contaminate the recordings. We further conclude that the clonic phase starts as a response to brain activity that can be only established when brain oscillations are slow enough to be followed by the muscles.

Download file:

Download Data & software: two sample EEG epileptic seizures, and the software used can be downloaded from:

Please e-mail me for comments. Cheers,


Rodrigo Quian Quiroga
Sloan-Swartz Center for Theoretical Neurobiology. Div. of Biology, 139-74.
California Institute of Technology
1200 E. California Blvd.
Pasadena, CA 91125
Tel/Fax: (626) 395 8337 / 795 2397
All times are GMT + 1 Hour
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