DIFFERENT PATTERNS OF FORE-HINDLIMB COORDINATION DURING OVERGROUND LOCOMOTION IN CATS WITH VENTRAL AND LATERAL SPINAL LESIONS

The effect of large, low thoracic (T10-T11), partial spinal lesions in volving the ventral quadrants of the spinal cord and, to a different e xtent, the dorsolateral funiculi, on fore-hindlimb coordination was ex amined in cats walking overground at moderate speeds (40-100 cm/s). Th ree different forms of impairment of fore-hindlimb coordination depend ing on the extent of the lesions, were observed. Lesions sparing the d orsolateral or the ventral funiculus on one side preserved the equalit y of the fore- and hindlimb locomotor rhythms but changed the coupling between the movements of both girdles as compared to intact animals. Larger lesions in which, in addition to the ventral quadrants of the s pinal cord, also major parts of the dorsolateral funiculi were destroy ed elicited episodes of rhythm oscillations in both girdles, which app eared at the background of a small difference in these rhythms. Lesion s destroying almost the whole spinal cord induced a permanent differen ce (about 200 ms) in the step cycle duration of the fore- and the hind limbs. However, even in these animals some remnant form of fore-hindli mb coordination was found. The results suggest that dorsolateral funic uli play a major role in preserving the equality of rhythms in the for e- and the hindlimbs, while lesions of the ventral quadrants change th e coupling between limbs.