Fig. 7

Chronically epileptic PACK and bPAC mice lack epileptiform bursts in the contralateral hippocampus. A Mice were injected with kainate in the left hippocampus and AAV9 carrying PACK, bPAC, or no virus in the contralateral hippocampus. B Two weeks later, wire electrodes were implanted into the kainate-injected ipsilateral hippocampus (HCi) and the virus-injected contralateral hippocampus (HCc). In PACK and bPAC mice, an optic fiber was implanted at a 30° angle adjacent to the electrode in HCc. C Three-hour LFP recordings with and without optogenetic manipulations were performed as previously in healthy PACK/bPAC mice. “No virus” mice were recorded only for 3-h reference recordings. D Representative section of an ihpKA PACK mouse showing hippocampal sclerosis in HCi with cell loss in CA1, CA3, and hilus regions as well as granule cell dispersion (GCD). PACK-mCherry was expressed in dorsal CA1 of HCc. Representative LFP snippets from E PACK-expressing, H bPAC-expressing, and K “no virus” kainate-injected mice in the chronic phase of epilepsy. E–M Spontaneous epileptiform bursts (hypersynchronous spiking activity, marked in green) were detected by an automated algorithm [36], and quantified as burst ratio, a fraction of recording spent in bursts. Each recording type was repeated twice and the mean of burst ratio of the two is presented for each animal. E–G PACK (n = 5) and H–J bPAC (n = 3) ihpKA mice had regularly occurring epileptiform bursts in HCi but no propagation to HCc during pre-recordings as well as during and after illumination. K In contrast, ihpKA mice without virus expression (n = 5) frequently showed burst propagation to HCc. L The burst ratio in HCi was similar in PACK, bPAC, and “no virus” mice, M whereas in HCc, the burst ratio was significantly above zero in “no virus” epileptic mice (33–36 days after ihpKA, average burst ratio during a 3-h reference recording). One-way ANOVA with Dunnett’s multiple comparison test, *p < 0.05. Mean presented with SEM as error bars. Individual data values are presented in Additional file 3