Carbachol-induced EEG ‘theta’ activity in hippocampal brain slices

Application of the cholinergic agonist carbachol (50 μM) produced θ-like rhythmical waveforms, recorded in the stratum moleculare of the dentate gyrus. Atropine sulfate (50 μM) antagonized the carbachol-induced θ-like activity, consistent with this action of atropine in vivo. These results provide the first direct evidence that hippocampal neurons are capable of producing synchronized slow- wave activity when isolated from pulsed rhythmic inputs of the medial septum and other brain regions.