Journal of Neuroscience, Vol 5, 1276-1282, Copyright © 1985 by Society for Neuroscience
Development and characteristics of airstepping in chronic spinal cats
CA Giuliani and JL Smith
Airstepping, walking-like movements of the hindlimbs, is a commonly
observed behavior in chronic spinal animals when they are held vertically.
The purpose of this study was to: describe the development of airstepping
after spinalization and compare it to the onset of segmental reflexes,
characterize the EMG pattern of muscle activity during spontaneous
airstepping, and examine the effects of sensory perturbation on the
characteristic pattern. Airstepping was analyzed during three conditions of
tonic sensory perturbation which included: tail pinching, tape applied to
one hindpaw, and immobilization of the ankle and knee in a plaster cast.
Seven adult cats were spinalized at T- 12, and bipolar electrode wires were
surgically implanted in selected hindlimb muscles at the hip, knee, and
ankle. Testing began within 48 hr of transection. Segmental reflexes and
paw-shake responses were present in the first week; however, the earliest
observed airstepping occurred during tail pinching at 2 weeks after
surgery, and the average onset of spontaneous airstepping (without
exteroceptive stimuli) was at 33 days. The average cycle period of
spontaneous airstepping (691 msec) was comparable to the shortest periods
reported for fictive rhythms and to treadmill walking between 1 and 2
m/sec. Intralimb coordination was characterized by flexor and extensor
synergies typical of locomotion, while interlimb coordination was
characterized by alternating cycles similar to that reported for treadmill
walking and fictive locomotion. Neither intralimb nor interlimb patterns of
coordination were altered by conditions of sensory perturbation, although
cycle period and EMG recruitment level were variable. Many characteristics
of airstepping are similar to those of treadmill and fictive
locomotion.(ABSTRACT TRUNCATED AT 250 WORDS)
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