Changes of the afterdischarge threshold during the limbic or neocortical kindling in cats

The afterdischarge threshold (ADT) in the limbic foci is reduced during limbic kindling. However, the changes of the ADT in the remote brain regions which receives no kindling stimuli remain unknown. To investigate the progressive neuronal changes during kindling, changes of the DAT were observed in the primary kindled sites and seconday unstimulated sites (pyriform cortex : PC and entorhinal cortex : EC) in amygdala (AM), hippocampal (HIPP) or neocortical (anterior portion of the suprasylvian gyrus : SS) kindled cats. The seizur threshold rapidly decreased, not only in the primary focus (AM or HIPP) but also in the remote brain regions (PC and EC), in the early process of acquisition of the limbic epileptogenesis and that the reduction of the ADT was closely related to the development of seconday epileptogenesis. In perticular, the PC could acquire the neuronal hypere xcitability during limbic kindling. However, in contrast to limbic foci, no signgificant changes of the ADT in either primary focus (SS) or secondary focus (PC and EC) was observed. This suggest-ed that the necortical seizure develops due to another neuronal mechanism which differs from the mechanism of the limbic seizure