Ultrafast EEG Frequencies and Epileptology.
Abstract number :
2.075
Submission category :
Year :
2001
Submission ID :
2279
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
D.L. Sherman, PhD, Biomedical Engineering, Johns Hopkins University, Baltimore, MD; N. Zhang, MD, Biomedical Engineering, Johns Hopkins University, Baltimore, MD; M.A. Mirski, MD, PhD, Anesthesiology & Critical Care Medicine, Johns Hopkins University, Bal
RATIONALE: This study aims at the elucidation of ultrafast frequencies under epileptic conditions.
METHODS: This study is based on 10 Sprague-Dawley rats in general anesthesia obtained by halothane (0.5%). EEG recordings were obtained from neocortex screw electrode, posterior & anterior thalamus and hippocampal (CA1/2) twisted pairs. The EEG frequency range included the ultrafast band from 100 to 400 Hz.
RESULTS: Spikes were usually limited to neocortex; while ultrafast ripples (200-300 Hz) represented the predominant epileptic EEG manifestations of PTZ seizures. At times ripples and spikes became synchronous with a fixed time lag, mostly at a rate around 5-7/s with hippocampal and (less commonly) thalamic maximum. The neocortical level showed massive spiking, but only suggestions of ripples.
CONCLUSIONS: Ascending fast volleys of neuronal discharges can engender both ripples and spikes. It is also known that pronounced volleys result in cortical flattening with the EEG picture of electrodecremental seizure activity which, in reality, consists of very low voltage ultrafast spiking. This can be clarified by the extension of spectrum into the ultrafast range. The exact relationship between epileptic ripples and classical spikes still remains debatable. In addition, the extension into the ultraslow domain (DC recording) would provide further information. Our epileptological insights are certainly deepened by widening of the EEG frequency range.
Support: NINDS RS35528