CA1 hyperexcitability is maintained 7 days after KA insult. (A) Schematic showing electrode placement. Dotted line indicates surgical separation of CA3. (B) Example of synchronized neuronal burst firing under Mg2+-free conditions at the 7 day post KA time-point (C) IBI in cultures 7 days after KA insult and age-matched controls prior to and after surgical separation of CA3 (* p < 0.05, n = 6, ANOVA). (D) Burst duration in CA1 7 days after KA treatment, prior to and after CA3 deafferentation (* p < 0.05, n = 6, ANOVA). Closed bars are controls, open bars are 8 h KA-treated +7d.