Interaction of symmetrical limbs during controlled locomotion

We have studied the controlled locomotion of the mesencephalic cat on a treadmill with two belts-left and right-the speed of which may be independently changed. For a two- and threefold difference in speeds of the belt the symmetrical limbs of the animal perform stepping movements with the same rhythm (with identical duration of the cycles). The structure of the stepping cycle of the limbs remains the same as for the corresponding speed of locomotion with the belts "tied". For a considerable difference in the speed the interaction of the limbs changes and stepping movements may appear with a ratio of the duration of the cycles of 1:2.