Impairments in limb actions after dorsal funiculi section in cats.

A study of the forces exerted by cats against the ground when jumping from a platform equipped with force transducers, was carried out. The study, complemented by film analysis of the jump, attempted to disclose some of the mechanisms underlying the decrease in efficiency and accuracy in releasing a moving piece of liver observed after dorsal funiculi section above C1 level. The results showed that after the lesion, peak force and height of jump were significantly reduced. However, angle of take-off, an index of force distribution in the three axes of rectangular coordinates remained unchanged. Intact cats consistently extend their forelimbs in a smooth and progressive way toward the liver in order to release it. The distance between the tips of the forelimbs remained more or less constant during the flight. Postoperatively, instead of the regular pattern described, the extension of the limbs was interrupted by fast marked flexion movements and the distance between their tips increased significantly during the flight. Peak extension of the forelimbs was also decreased after surgery. The results are interpreted in terms of the different disruption of the various components (proprio and exteroceptive) that make up fasciculus gracilis and cuneatus of the dorsal funiculi.