Non convulsive spike-wave discharges do not induce Fos in cerebro-cortical neurons.

Immunohistochemical localisation of Fos was used as a marker of neuronal activity to demonstrate neurons active during non-convulsive spike-wave epilepsy. Fos-positive neurons in cortex and several subcortical areas were counted. In undisturbed animals. Fos counts were not related to spike-wave in any region. With the electroencephalographic (EEG) recording procedure. Fos induction occurred in all regions, even after habituation. However, in central cortex, counts were found to be inversely related to spike-wave duration. This suggests that neuronal activity is not increased during spike-wave and that the central cortex in these animals is less responsive to arousal than in non-epileptic animals.