In vivo Subdural ECoG Versus in vitro Slice Recodings in Human Neocortical Epilepsy
Abstract number :
3.129
Submission category :
Year :
2000
Submission ID :
1745
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Stephen M Dombrowski, Milan Radojicic, William E Bingaman, Imad M Najm, Eldad J Hadar, Hans O Luders, Damir Janigro, Cleveland Clin Fdn, Cleveland, OH; Cleveland Clin Fdn, Cleveland, HI.
RATIONALE: Cortical epileptogenesis can result from factors such as abnormalities in neuronal and glial function, or changes in the composition of extracellular space. Surgical specimens obtained from patients affected by medically intractable seizures allows the study of the cellular basis of human epilepsy. Cortical ECoG signals originating from large groups of neurons are commonly used to localize "focal" epileptogenic regions. Our goal was to correlate intraoperative ECoG and in vitro slice recordings of spontaneous and evoked activity from patients affected by intractable seizures due to neocortical epilepsies with varying etiologies. METHODS : Intraoperative subdural grids were used to record ECoG signals identifying "epileptic" vs. "non-epileptic" regions from 7 patients undergoing cortical resection. In vitro recordings were made from 300 ?m vibratome-cut slices maintained under quasiphysiological conditions at 30oC. Electrical (100-500 ?A, 0.1-1Hz) and phamacological (3mM Cs+) stimulation was administered to evoke cortical activity. RESULTS: Results obtained from these patients demonstrated no clear-cut correlation between ECoG activity and in vitro slice physiology. Positive correlation between in situ and in vitro interictal bursting was observed only in one slice from a patient with cortical dysplasia. Slices from 6 of 7 patients revealed low frequency spontaneous activity (LFSA) and rare paroxysmal depolarizing shifts (PDS) in response to repetitive stimulaton (0.1-1.0 Hz). Blockade of glia spatial buffering by 3mM Cs+ (J. Neuroscience, 1997, 17(8) 2813-24) caused more prominent LFSA and increased PDS activity in slices from active foci: this effect was less pronounced in slices from "non-epileptic" regions. CONCLUSIONS: These preliminary results suggest that "epileptic" tissue in vitro does not share all the characteristics recorded intraoperatively, and that altered potassium homeostasis may underlie abnormal activity in epileptic tissue. Supported by NIH-NINDS 51614, NIH-NHLBI 18895, NIH-NINDS 02046.