[Spontaneous generation of locomotor rhythmicity].

After dissection of the brain stem caudal to the rostral border of pons Varolii, a locomotor ability of the forelimbs was studied in cats with the spinal cord sectioned at the low thoracic level. Two groups of preparations were obtained. The 1st one was able to walk on the moving treadmill belt. The Horsley--Clarke coordinate of the dorsal border of the section was A3--A0 and of ventral one A5--A3.5. Preparations of the 2nd group which were not able walking and those which could walk, generated spontaneously alternating movements at a locomotor rrhythm. The 2nd group had dorsal border of the section at A2.5--P1.5 and ventral one at A4--A1.5. The spontaneous rhythm occurred in various positions of the forelimb. In the middle position the elbow flexor and extensor were activated alternatingly. The spontaneous movements seem to be related to walking on the treadmill belt. The spontaneous rhythm appears to be a locomotion component.