[Presynaptic inhibition in the rat spinal cord in ontogeny and its relationship to depression of monosynaptic reflexes].
Cheking the parameters of potentials from the dorsal surface of the spinal cord, studies have been made on the development of depolarization in the primary afferent terminations. It was shown that during the development of animals the amplitude of N- and P components increase indicating progressive development of afferent connections in the spinal cord and maturation of presynaptic inhibition mechanisms. Parallel studies were made on the depression of monosynaptic reflexes conditioned by stimulation of antagonists. It was shown that maximum inhibition develops 20-40 ms after the conditioning coinciding with the highest amplitude of P component. In new-born rats, the recovery of the reflex takes more time than depolarization of the primary afferent terminations, this difference indicating that the depression is only partially due to presynaptic inhibition. Homosynaptic depression plays an important role, its duration and intensity being more significant in new-born animals. The duration of homosynaptic depression decreases with age. Under these conditions, the main mechanism of limitation of afferent input involves the depolarization of the primary afferent terminations.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D004558:Electric Stimulation; D005071:Evoked Potentials; D005727:Ganglia, Spinal / Q000502:physiology; D009433:Neural Inhibition; D051381:Rats; D012023:Reflex, Monosynaptic; D013116:Spinal Cord / Q000254:growth & development / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
Presinapticheskoe tormozhenie v spinnom mozge u krys v ontogeneze i ego sviaz' s depressieĭ monosinapticheskikh refleksov.