[Postnatal development of the scratch reflex in rabbits].
The development of the scratch reflex was studied in newborn (up to 2 months old) rabbits in norm and after elimination or activation of some parts of their nervous system (reticular formation, cerebellum, caudate nucleus, cerebral cortex, superior cervical sympathetic ganglia). The experiments with the section of the brain stem at the border between the medulla and the midbrain showed that in very young (5-10 days old) rabbits in norm the scratch reflex is controlled by the spinal cord with no influences of structures situated above the section's level. Later on the spinal mechanism of the scratch reflex becomes subject to supraspinal influences, among which in 2-3 weeks old animals facilitatory effects are predominant produced, in particular, by the reticular formation and the cerebellum, whereas in older age prevail inhibitory influences of the cerebral cortex, cerebellum, caudate nucleus and the sympathetic nervous system.