A comparison of treadmill locomotion in adults cats before and after spinal
Marc B[acute]elanger, Trevor Drew, Janyne Provencher and Serge Rossignol.
Centre de Recherche en Sciences Neurologiques, D[acute]epartement de
Physiologie, Facult[acute]e de M[acute]edecine, Universit[acute]e de
Montr[acute]eal, Montr[acute]eal, Qu[acute]ebec, CANADA.
APStracts 3:0021N, 1996.
SUMMARY AND CONCLUSIONS
1. The aim of this study was to document the kinematics and the
electromyographic activity recorded from several muscles during treadmill
locomotion in the same cat (N=4), before and after spinalisation by using a
chronic implantation method. Because identical experimental and control
conditions were used, it was possible to establish similarities and
differences in the timing and amplitude of the muscular activity and
kinematics under the intact and spinal conditions in the same animal. The data
presented in this paper were collected when the cats had fully recuperated a
stable locomotor pattern, walking at a constant speed of approximately 0.4
m/s. 2. The adult spinal cats retained many of the general locomotor features
and EMG characteristics seen before transection. However there were also
important differences. 3. There was a reduction in the step length which was
principally due to the forward placement of the paw at the onset of the
stance. Similarly, there was a decrease in the step cycle duration which was
attributed to a reduction of both the stance and swing phases. 4. The overall
angular excursions of the hip, knee and ankle were generally similar, although
joints were sometimes more flexed at all phases of the step cycle. In
contrast, the overall excursions of the metatarsophalangeal joints was much
greater in all four cats after spinalisation due to a paw drag during the
initial portion of the swing phase which exaggerated the plantarflexion. 5.
There was an increase in the EMG amplitude of the flexor muscles at two of
three joints (i.e., hip, knee and ankle) in each cat after spinalisation. The
change in the EMG amplitude of the extensors did not appear to be as
consistent as that observed in the flexor muscles. When looking at each cat
individually, the post-spinalisation extensor activity decreased at two of
three joints in two cats while the opposite was true for the other two cats.
6. There was a delay in the onset of the knee flexor (Semitendinosus) activity
while the ankle dorsiflexor (Tibialis Anterior) activity started earlier with
respect to the beginning of the swing phase. The onset of hip flexors was
somewhat more variable. This change in the timing of flexor activity was most
probably responsible for the paw drag at the onset of the swing phase. 7. The
present results reveal that despite the few differences, the spinal cord and
the hindlimbs afferents are capable of generating very good locomotor patterns
with almost normal kinematics and EMG characteristics.
Received 30 August 1995; accepted in final form 10 January 1996.
APS Manuscript Number J573-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 January 96