Unexpected Motor Patterns for Hindlimb Muscles During Slope Walking in the
Cat.
Smith, Judith, and Patricia Carlson-Kuhta.
Laboratory of Neuromotor Control, Dept. of Physiological Science and the
Brain Research Institute, University of California, Los Angeles, California,
90095-1568.
APStracts 2:0239N, 1995.
SUMMARY AND CONCLUSIONS
1. Hindlimb kinematics and motor patterns were assessed from high-speed
cin[acute]e film synchronized with electromyographic (EMG) data from cats
trained to walk on a walkway placed at four grades (25, 50, 75, 100%). 2.
Flexor muscles of the hip (IP) and ankle (TA) had similar activity patterns
for the swing phase of up- and down-slope walking; both flexor muscles also
had stance-related activity during down-slope walking and this was unexpected.
Extensor muscles of the hip (ABF, ASM), knee (VL), and ankle (LG) were active
during the stance phase of up-slope walking. The VL and LG activity was
reduced in duration during stance of down-slope walking and centered around
paw contact. Hip extensors, however, were totally inactive during stance of
down-slope walking, and this was not expected. 3. Flexor muscles at the hip
and ankleÄnot extensor musclesÄdominated the stance phase of down-slope
walking, especially at the steeper slopes. This switch in motor patterns may
be required to counterbalance external forces that produced extension at the
hip and ankle joints during the stance phase of down-slope walking. Neural
mechanisms for programming stance-related activity of flexor muscles are
discussed.
Received 12 May 1995; accepted in final form 8 August 1995.
APS Manuscript Number J322-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.