[Influence of the efferent vestibular system on the vestibulo-spinal reflexes in the guinea pig]

Influence of the efferent vestibular system on the vestibulo-spinal activity was investigated in the decerebrated, decerebellated guinea pigs. The efferent vestibular system was excited by electrical stimulation of the domain of efferent neurons in the medulla. Electromyographic activity of left and right triceps brachii was used as a test reaction. Muscle activity was initiated by means of the crossed extensor reflex and locomotion evoked by mesencephalic locomotor region stimulation. Adequate vestibular stimulation was performed by static shifts and cyclic tilting of an animal about a longitudinal axis. It has been demonstrated that the efferent system bilaterally inhibits the vestibulo-spinal activity. The stimulation of vestibular efferents decreases the intensity of vestibular influences, but does not change dynamics of vestibulo-spinal reflexes. Mechanisms of the vestibular efferent action on the vestibular control of the spinal motor activity are discussed.