EFFECT OF SEPTO-HIPPOCAMPAL DISCONNECTION UPON NEURONAL-ACTIVITY OF SEPTUM

  • 1 January 1975
    • journal article
    • research article
    • Vol. 25  (5) , 1044-1052
Abstract
Extracellular recording of neuronal activity was performed in the medial and lateral septal nuclei (MS and LS) in unanesthetized rabbits after coagulation of septo-hippocampal connections. The MS neuronal activity had many pathological features. The LS activity was normal in every respect. Spontaneous activity, reactivity to sensory stimuli and main characteristics of responses to sensory stimuli were preserved in LS (and in a part of MS neurons). Sensory effects were augmented in intensity and duration, the number of neurons in LS with .theta.-bursts increased 2-fold and .theta.-bursts were more regular than in control animals. These effects may be explained by an increase of ascending RF reticular formation influences, which is supported by the fact of outstanding similarity between sensory and reticular effects in septal neurons after hippocampal disconnection. The number of units with inhibition of activity in response to sensory stimuli decreased; habituation of responses was absent. Hippocampal influences are apparently necessary for the organization of inhibitory phenomena in the septum, and for processes of gradual habituation.

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