Contrôle de l'activité des fibres fusimotrices dynamiques et statiques par la formation réticulée mésencéphalique chez le chat

Abstract

Effects of repetitive stimulation of the mesencephalic reticular formation (MRF) on the static discharge and dynamic sensitivity of muscle spindle primary endings (soleus muscle) were studied in cats anaesthetized with Halothane (Fluothane). By progressive increasing the depth of anaesthesia three different fusimotor effects could be observed: 1. A static effect; the static discharge of the primary endings was strongly increased; the response to phasic stretch was decreased or remained unaltered. 2. A dynamic effect; the dynamic sensitivity of the primary endings was powerfully increased while the rate of discharge under static conditions was only slightly augmented. 3. A depressant effect; the static discharge and the dynamic sensitivity of primary endings were decreased. A static effect; the static discharge of the primary endings was strongly increased; the response to phasic stretch was decreased or remained unaltered. A dynamic effect; the dynamic sensitivity of the primary endings was powerfully increased while the rate of discharge under static conditions was only slightly augmented. A depressant effect; the static discharge and the dynamic sensitivity of primary endings were decreased. Repeated stimulation elicited successive static and dynamic effects. No specific regions within the MRF could be related to a particular effect.

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