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. Ann Neurol 2015;77:541–546