LONGITUDINAL COORDINATION BETWEEN VESTIBULAR AND SPINAL REFLEX SYSTEMS UNDERLYING BULBAR RETICULAR FORMATION

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Experiments were performed on chloralose anesthetized cats to analyze longitudinal vestibulo-spinal coordinations. Stimulation of vestibular afferent nerves elicited two reflex responses from bilateral spinal outflows, early and late, from spinal ventral and dorsal roots and cord dorsum. The early part of the spinal response may be due to the relatively direct bypasses the bulbar reticular formation. In contrast the bulbar reticular formation may be underlying the late part of the spinal responses. Alternately, asphyxia and Nembutal anesthesia affected the late part of spinal responses more easy to abolished than the early ones. Prolonged blocking interaction was obtained between the late part of the vestibular evoked spinal responses and other reflex responses, i.e., spino-bulbo-spinal, spino-bulbo-cranial and cortically evoked extrapyramidal activities.These reflexes were relaying the bulbar reticular formation, thus, these blocking may be obtained at the bulbar level.