[Reticular structures and reticulospinal pathways participating in initiation and inhibition of spino-bulbo-spinal activity].

Efferent discharges in intercostal nerves and activity of reticulospinal fibres during stimulation of the brain stem reticular formation, intercostal splanchnic nerves were recorded in cats anesthetized with chloralose (50 mg/kg). It is found that the structures involved in the transmission of spino-bulbo-spinal activity are located in the medial bulbar and pontine reticular formation as well as in its lateral regions. The structures producing long-lasting (300-800 ms) inhibition of spino-bulbo-spinal reflexes are also wide distributed in the brain stem, especially in the pontine region. Recording of activity of single reticulospinal fibres in the ventral (conduction velocity 16-120 m/s) and lateral (17-100 m/s) funiculi during spino-bulbo-spinal reflexes showed that both medial and lateral reticulospinal tracts may be involved into this reflex mechanism. New evidence is obtained that the inhibition of spino-bulbo-spinal reflexes may be located at supraspinal level.