Network interactions in the limbic system and epileptiform synchronization

Neuronal networks in the hippocampal and parahippocampal regions are damaged in patients affected by temporallobe epilepsy (TLE). The consequences of the lesions are still poorly understood, but evidence suggests thatinteractions between the entorhinal cortex (EC) and hippocampus are changed from polysynaptic to monosynaptic,bypassing the CA3 region. In addition, the perirhinal/postrhinal cortex (PC), which normally filters the signalsentering the hippocampal formation, may lose its capacity to inhibit the paroxysmal neuronal activity directed to orleaving the EC. Finally, emphasis has recently been placed on the epileptogenic role of the subiculum that isdisinhibited both in epileptic animals and in TLE patients.