EEG and seizure threshold in normal and lissencephalic ferrets.
Changes in EEG and susceptibility to electrically induced seizures were examined in the ferret with lissencephaly produced by exposure to a single injection of methylazoxymethanol acetate (MAM Ac) given to the pregnant jill on gestation day 32. Ten lissencephalic and 11 normal ferrets were chronically implanted with 14 cortical stainless steel electrodes. EEG records were sampled from various stages of the sleep/awake cycle. Six of each group were subjected to electrical stimulation for seizure threshold. Although the number of stimulations and the current intensity required to produce epileptiform afterdischarges (AD) and seizures were not different between the two groups, the lissencephalic ferrets had significantly longer AD and seizures, and a greater number of generalized seizures, indicating an enhanced seizure susceptibility. The EEG of the lissencephalic ferrets was characterized by increased slow wave activity within the low theta band range, extreme spindle activity, focal or multifocal slow and sharp waves, spikes, or spike and slow wave complexes. The differences in the EEG were more pronounced during drowsiness and sleep stages. The brains of all of the treated animals were lissencephalic and hydrocephalic, and weighed significantly less than those of the normals. The cerebral cortex was thin and flattened, with the parieto-occipital region most severely affected. Heterotopic foci were found in the cerebellum as well as in the cerebral cortex. Abnormalities in the configuration of the cerebellar folia were also seen. Comparison between the electrophysiological and neuropathological data suggests that the extent of the extreme spindle activity, and longer AD and seizure duration depended on the degree of cerebellar dysplasia, whereas the EEG focal abnormalities were related to lesions in the cerebral hemispheres.
D000818:Animals; D002540:Cerebral Cortex / Q000002:abnormalities* / Q000473:pathology; D004558:Electric Stimulation; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005289:Ferrets; D008297:Male; D008746:Methylazoxymethanol Acetate / Q000031:analogs & derivatives; D012890:Sleep / Q000502:physiology; D013577:Syndrome
D008746:Methylazoxymethanol Acetate; C030667:methylazoxymethanol