This is an excerpt from Neuromechanics of Human Movement 5th Edition eBook by Roger M. Enoka.
Example 7.7 Capabilities of Spinal Pathways
The existence of locomotor CPGs in the spinal cord has considerable significance for individuals with spinal cord injuries. The observations of Graham Brown (1911) have been extended to demonstrate a number of details about the control of locomotion: (1) A decerebrated cat (CPG disconnected from higher centers at the level of the midbrain) can walk on a treadmill when a specific region in the brain stem is stimulated electrically; (2) spinalized (CPG disconnected from higher centers at the spinal level) cats can be trained to walk; (3) electrical stimulation of the lumbosacral cord in paraplegic mammals can produce a locomotor rhythm; and (4) a human with no supraspinal control below a low thoracic lesion can learn to stand and initiate steps. These achievements are possible due to the interactions between the spinal locomotor system, including the CPGs that produce the rhythm, and afferent feedback from sensory receptors.
A series of studies by Reg Edgerton and colleagues on the speed and specificity of the learning response has remarkably demonstrated the capabilities of the spinal cord (Roy et al., 2012). For example, a spinalized cat stepping on a treadmill can learn within a single step cycle to flex the limb more during the swing phase in order to avoid an obstacle. Similarly, spinalized rats quickly learn to alter the locomotor rhythm to accommodate a disturbing force applied to the hindlimbs. The specificity of these adaptations is indicated by improvements in the stepping ability of spinalized cats trained to step and the standing ability of those trained to stand. These capabilities have implications for the rehabilitation strategies prescribed for individuals with spinal cord injuries (Edgerton & Roy, 2012).
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