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Epileptic Disorders

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Dissociation between in vitro and in vivo epileptogenicity in a rat model of cortical dysplasia Volume 9, issue 1, March 2007

Figure 1 Macroscopic and microscopic appearance of the neocortical freeze-induced microsulcus. A) The microsulcus is clearly visible macroscopically on the surface of the hemispheric convexity (open arrow) and on coronal cross sections (filled arrow). B) Microsulcus in a coronal brain slice from a freeze-lesioned rat, while in vitro field potential recordings were performed. The white star shows the position of the recording glass micropipette at the rim of the lesion. C) Low-magnification photomicrograph of a cresylecht violet (CV) Nissl substance-stained coronal section from a freeze-lesioned hemisphere. D) Low-magnification photomicrograph of a CV-stained coronal section from a sham-operated (control) rat.

Figure 2 Representative normal EEG recordings at resting stage at approximately day 10 after PTZ-injection: A) freeze-lesioned rat, B) control rat. LF = left frontal, RF = right frontal, LP = left parietal, RP = right parietal, REF = reference electrode (frontal sinus).

Figure 3 Zero-magnesium-induced epileptiform field potentials (EFP) recorded from coronal brain slices from freeze-lesioned rats (FL slices; A), compared to control animals (CTRL slices; B); 10 min periods depicting EFP repetition rate (left traces); single EFP bursts displayed at a higher time resolution (right traces).A) Field potentials (FP) recorded from a FL slice. FP were simultaneously recorded from the perilesional cortex in the immediate vicinity of the microsulcus (LES), and from a site 8 mm lateral of the microsulcus (LAT). Zero-magnesium-induced EFP were ictal-like, with an initial negative spike, followed by a prolonged repolarization phase with superimposed afterdischarges. EFP recorded from LES and LAT positions did not differ in terms of repetition rate, maximum amplitude, or burst integral.B) FP recorded from a CTRL slice. Zero-magnesium-induced EFP were of the interictal-like type, consisting of an initial negative spike and a slow repolarization phase which was significantly shorter than in FL slices. Calibration bars in B apply to all traces.