Consequences of cortical dysplasia during development in rats.
OBJECTIVE
To determine whether focal cortical dysplasia alters excitability in regions distant to the region of the dysplasia.


METHODS
We studied the physiological consequences of cortical dysplasia induced by either one or three freeze lesions at birth. Seizure susceptibility was assessed at age 35 days by amygdala kindling. c-fos immunostaining was performed after kainic acid-induced seizures at 10, 20, or 30 days to evaluate the patterns of neuronal activation.


RESULTS
Freeze lesions consistently produced uniform regions of dysplasia. No significant differences in seizure susceptibility, as measured by afterdischarge threshold and kindling rate, were seen between controls and rats receiving either one or three freeze lesions. c-fos activation after kainic acid injection was not observed in the region of the dysplasia. However, rats with freeze lesions at age 30 days demonstrated asymmetric c-fos staining with greater staining in CA1 ipsilateral, than contralateral, to the lesion.


CONCLUSIONS
Focal cortical dysplasia results in enhancement of c-fos activation in regions outside the borders of the dysplasia. However, as indicated by kindling rate, the functional consequences of these alterations do not appear to be robust.
Holmes
G L
GL
Department of Neurology, Harvard Medical School, Children's Hospital, Boston, Massachusetts 02115, USA.
Sarkisian
M
M
Ben-Ari
Y
Y
Liu
Z
Z
Chevassus-Au-Louis
N
N
D000679:Amygdala / Q000187:drug effects / Q000503:physiopathology; D000818:Animals; D002540:Cerebral Cortex / Q000002:abnormalities* / Q000254:growth & development* / Q000503:physiopathology; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004827:Epilepsy / Q000139:chemically induced / Q000209:etiology / Q000503:physiopathology*; D005615:Freezing; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000494:pharmacology; D007696:Kindling, Neurologic / Q000502:physiology*; D019599:Mossy Fibers, Hippocampal / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013238:Stereotaxic Techniques
D016760:Proto-Oncogene Proteins c-fos; D007608:Kainic Acid