Organization of locomotor synergism

1. (1) Stimulation of a definite region of the mid-brain produces locomotion in the mesencephalic cat deprived of inherent motor activity. The main features of the induced locomotion are similar to those observed previously in intact animals. 2. (2) Stimulation of the locomotor region changes certain segmental reflexes in a direction promoting optimal co-ordination of work of the muscles of the stepping limb. 3. (3) Stimulation of the mid-brain causes step movements of the deafferentated hind limbs providing the intact fore limbs perform step movements. In the curarized preparations stimulation of the locomotor region as such does not lead to synchronized rhytmic activity of the motor neurones. 4. (4) Stimulation of the locomotor region of the mid-brain in the curarized preparation activates the reflexes induced by passive cyclic movements both of the particular and the other limbs. 5. (5) It is assumed that the appearance of locomotion on stimulation of the mid-brain is due to the following processes. Firstly, the segmental apparatus is brought to a state ensuring in the presence of existing afferentation, step movements of the limb. Secondly, a system of interaction of the neural mechanisms of different limbs is formed resulting in harmonization of their movements.