Abstracts

Rationale: We previously created a novel rat model of focal cortical dysplasia (FCD) using prenatal freeze lesioning. These rats, which had FCD in the left hemisphere, showed vulnerability for developing kindling. However, they lacked spontaneous seizures. In this study, we created a model with FCD in the bilateral hemispheres and investigated whether this bilateral prenatal freeze-lesion rat model shows spontaneous seizures. Methods: At 18 days post-conception, a frozen probe was placed on the bilateral scalps of Sprague-Dawley rat embryos, for 4 seconds, through the uterus wall, producing bilateral cortical dysplasia. We also created unilateral freeze-lesion rats (2 points of the lesions). EEG (1 hr/day, 5 days/week, for 6 weeks) recordings were made from both frontal cortices and the hippocampi of postnatal day 42 (P42) bilaterally freeze-lesion (n=9), unilateral freeze-lesion (n=6), and non-freeze-lesion (n=7) rats. Results: Four bilateral freeze-lesion rats showed spontaneous seizures, which arose from the bilateral hippocampi and evolved to the bilateral hemispheres. Spontaneous seizures were not observed in unilateral freeze-lesion and non-freeze-lesion rats. Conclusions: Prenatal freeze-lesion rat models might have spontaneous seizures when bilateral cortical dysplasia is produced.