title: [Functional characteristics and topography of spinal tracts involved in low- and high-threshold startle reflexes].
abstract: Electrophysiological and topographical properties of the spinal tract systems involved in two functional types of startle reflexes were studied in chloralose anesthetized cats: a high threshold reflex evoked by intense peripheral nerve stimulation (spino-bulbo-spinal, SBS, reflex) and low threshold evoked by tactile (T-reflex) and acoustic (A-reflex) stimulation. It was found that the mean maximal conduction velocity of descending transmission of SBS-reflexes was much less (30 m/s) than that of T- (85 m/s) and A-reflexes (100 m/s). Ascending conduction velocities for SBS- and T-reflexes were 70.8 and 40.2 m/s, respectively. It was established by partial spinal cord lesions that ascending tracts for T-reflex passed in dorsal and dorso-lateral funiculi; those for SBS reflexes were found not only in the latter but also in ventro-lateral and partially in ventral funiculi. Descending pathways for SBS reflex passed mainly in ventro-lateral funiculi and partially in the ventral ones. Descending pathways of T- and A-reflexes had a similar organization and were located mainly in the ventral and ventro-lateral funiculi. Functional organization of spinal tracts of all studied types of startle reflexes is discussed.
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001933:Brain Stem / Q000502:physiology*; D002415:Cats; D004558:Electric Stimulation; D007367:Intercostal Nerves / Q000502:physiology; D009431:Neural Conduction; D009434:Neural Pathways / Q000502:physiology; D013216:Reflex, Startle / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D014110:Touch
vernacular_title: Funktsional'nye kharakteristiki i topografiia spinal'nykh provodiashchikh puteĭ nizko- i vysokoporogovykh refleksov vzdragivaniia.