[Effect of acetylcholine and glutamate on septal neurons in vitro].

The activity of neurones of the medial septal nucleus was recorded in guinea pig brain slices in vitro during injection of acetylcholine (ACh) and glutamate (Gl) into the incubating medium. Gl produced stereotype initial activating influence, but in many units (12 out of 31) the activating phase was followed by a decrease of discharge frequency and an increase of spike amplitude. The effects of ACh depended upon the type of spontaneous neuronal activity. In units with a regular pacemaker-like activity it produced an increase of discharge frequency with slow, gradual onset and offset of response. In neurones with an irregular and burst activity ACh application evoked rhythmic bursts or increased their regularity with variable changes of the mean frequency in different units. The two functional types of the units in medial septum are discussed.