Theta-like activity in hippocampal formation slices: cholinergic-GABAergic interaction.

Brain slice preparations obtained from the rat were used to study cholinergic GABAergic interaction in mechanisms responsible for production of theta-like activity in hippocampal slices maintained in vitro. Bicuculline, a GABA-A antagonist, applied at 25 microM facilitated the effect of low concentration carbachol (25 microM) in inducing theta-like oscillations. At 100 microM, bicuculline increased the amplitude of carbachol-induced theta-like slow waves. This carbachol-bicuculline induced field potential was antagonized by a muscarinic blocker, atropine sulphate, and a GABA-A agonist, muscimol. These results provide in vitro evidence for cholinergic-GABAergic interaction in the production of hippocampal theta-like slow waves.