Interneuron activity leads to initiation of low-voltage fast-onset seizures.

Seizures in temporal lobe epilepsy can be classified as hypersynchronous and low-voltage fast according to their onset patterns. Experimental evidence suggests that low-voltage fast-onset seizures mainly result from the synchronous activity of γ-aminobutyric acid-releasing cells. In this study, we tested this hypothesis using the optogenetic control of parvalbumin-positive interneurons in the entorhinal cortex, in the in vitro 4-aminopyridine model. We found that both spontaneous and optogenetically induced seizures had similar low-voltage fast-onset patterns. In addition, both types of seizures presented with higher ripple than fast ripple rates. Our data demonstrate the involvement of interneuronal networks in the initiation of low-voltage fast-onset seizures.