[Effect of complete basal undercutting of the septum on the activity of its neurons].

Spontaneous and evoked by sensory stimuli neuronal activity of medial and lateral septal nuclei deprived of basal connections, was investigated in chronic unanaesthetized rabbits. After basal undercutting of septum many neurones in both nuclei produced highly regular "pacemaker-like" activity. The proportion of neurones with rhythmic bursts of spontaneous activity did not change, but the frequency of bursts decreased to 2.8--3.9 per second. Reactivity of neurones to sensory stimuli was low in both nuclei. Electric stimulation of the hippocampus was highly effective. The majority of septal neurones responded to each stimulus by a short (30--150 msec) inhibition. The problems in connection with possible organization of rhythmic theta-activity of septal neurones are discussed.