The effects of the gamma-aminobutyric acid (GABA) receptor antagonist bicuculline on rat hippocampal neurons recorded in slices and in the intact hippocampi kept in vitro were studied using whole-cell patch-clamp recordings. Bicuculline (10 microM) evoked ictal discharges in the intact hippocampus but only interictal discharges in conventional slices. Recording from the intact hippocampus in vitro is an alternative preparation to study the organization of the hippocampal neuronal network.