scholarly journals Altered activation patterns by triceps surae stretch reflex pathways in acute and chronic spinal cord injury

2011 ◽  
Vol 106 (4) ◽  
pp. 1669-1678 ◽  
Author(s):  
Alain Frigon ◽  
Michael D. Johnson ◽  
C. J. Heckman
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Stretch Reflex ◽  
Triceps Surae ◽  
Stretch Reflexes ◽  
Activation Patterns ◽  
Intact State ◽  
Hindlimb Muscles ◽  
Reflex Pathways ◽  
Cord Injury

Spinal reflexes are modified by spinal cord injury (SCI) due the loss of excitatory inputs from supraspinal structures and changes within the spinal cord. The stretch reflex is one of the simplest pathways of the central nervous system and was used presently to evaluate how inputs from primary and secondary muscle spindles interact with spinal circuits before and after spinal transection (i.e., spinalization) in 12 adult decerebrate cats. Seven cats were spinalized and allowed to recover for 1 mo (i.e., chronic spinal state), whereas 5 cats were evaluated before (i.e., intact state) and after acute spinalization (i.e., acute spinal state). Stretch reflexes were evoked by stretching the left triceps surae (TS) muscles. The force evoked by TS muscles was recorded along with the activity of several hindlimb muscles. Stretch reflexes were abolished in the acute spinal state due to an inability to activate TS muscles, such as soleus (Sol) and lateral gastrocnemius (LG). In chronic spinal cats, reflex force had partly recovered but Sol and LG activity remained considerably depressed, despite the fact that injecting clonidine could recruit these muscles during locomotor-like activity. In contrast, other muscles not recruited in the intact state, most notably semitendinosus and sartorius, were strongly activated by stretching TS muscles in chronic spinal cats. Therefore, stretch reflex pathways from TS muscles to multiple hindlimb muscles undergo functional reorganization following spinalization, both acute and chronic. Altered activation patterns by stretch reflex pathways could explain some sensorimotor deficits observed during locomotion and postural corrections after SCI.

scholarly journals Changes in Locomotor Muscle Activity After Treadmill Training in Subjects With Incomplete Spinal Cord Injury

2009 ◽  
Vol 101 (2) ◽  
pp. 969-979 ◽  
Author(s):  
Monica A. Gorassini ◽  
Jonathan A. Norton ◽  
Jennifer Nevett-Duchcherer ◽  
Francois D. Roy ◽  
Jaynie F. Yang
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Treadmill Training ◽  
Emg Activity ◽  
Incomplete Spinal Cord Injury ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Cord Injury

Intensive treadmill training after incomplete spinal cord injury can improve functional walking abilities. To determine the changes in muscle activation patterns that are associated with improvements in walking, we measured the electromyography (EMG) of leg muscles in 17 individuals with incomplete spinal cord injury during similar walking conditions both before and after training. Specific differences were observed between subjects that eventually gained functional improvements in overground walking (responders), compared with subjects where treadmill training was ineffective (nonresponders). Although both groups developed a more regular and less clonic EMG pattern on the treadmill, it was only the tibialis anterior and hamstring muscles in the responders that displayed increases in EMG activation. Likewise, only the responders demonstrated decreases in burst duration and cocontraction of proximal (hamstrings and quadriceps) muscle activity. Surprisingly, the proximal muscle activity in the responders, unlike nonresponders, was three- to fourfold greater than that in uninjured control subjects walking at similar speeds and level of body weight support, suggesting that the ability to modify muscle activation patterns after injury may predict the ability of subjects to further compensate in response to motor training. In summary, increases in the amount and decreases in the duration of EMG activity of specific muscles are associated with functional recovery of walking skills after treadmill training in subjects that are able to modify muscle activity patterns following incomplete spinal cord injury.

The tonic stretch reflex and spastic hypertonia after spinal cord injury

2006 ◽  
Vol 174 (2) ◽  
pp. 386-396 ◽  
Author(s):  
Adam J. Woolacott ◽  
John A. Burne
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Stretch Reflex ◽  
Cord Injury

Effect of spinal cord injury and its lesion level on stretch reflex modulation by cold stimulation in humans

2011 ◽  
Vol 122 (1) ◽  
pp. 163-170 ◽  
Author(s):  
H. Ogata ◽  
D.G. Sayenko ◽  
E. Yamamoto ◽  
T. Kitamura ◽  
S. Yamamoto ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Stretch Reflex ◽  
Reflex Modulation ◽  
Cold Stimulation ◽  
Cord Injury ◽  
Lesion Level

scholarly journals The recovery of standing and locomotion after spinal cord injury does not require task-specific training

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jonathan Harnie ◽  
Adam Doelman ◽  
Emmanuelle de Vette ◽  
Johannie Audet ◽  
Etienne Desrochers ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Specific Activity ◽  
Weight Bearing ◽  
Triceps Surae ◽  
Full Weight Bearing ◽  
Specific Training ◽  
Spinal Transection ◽  
Cord Injury ◽  
Complete Spinal Cord Injury

After complete spinal cord injury, mammals, including mice, rats and cats, recover hindlimb locomotion with treadmill training. The premise is that sensory cues consistent with locomotion reorganize spinal sensorimotor circuits. Here, we show that hindlimb standing and locomotion recover after spinal transection in cats without task-specific training. Spinal-transected cats recovered full weight bearing standing and locomotion after five weeks of rhythmic manual stimulation of triceps surae muscles (non-specific training) and without any intervention. Moreover, cats modulated locomotor speed and performed split-belt locomotion six weeks after spinal transection, functions that were not trained or tested in the weeks prior. This indicates that spinal networks controlling standing and locomotion and their interactions with sensory feedback from the limbs remain largely intact after complete spinal cord injury. We conclude that standing and locomotor recovery is due to the return of neuronal excitability within spinal sensorimotor circuits that do not require task-specific activity-dependent plasticity.

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