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7 Cards in this Set
- Front
- Back
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What are symptoms of spinal cord lesions? |
1. Can't walk by themselves 2. Muscle tone goes completely down in acute stage 3. Muscle tone recovers ~5 months after injury 4. On treadmill, can generate locomotive movements |
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What was the experiment using EMG to record muscle activity of spinal cord lesion patients? |
2 experimental groups: complete spinal cord transaction & incomplete lesions - Still able to walk without support to some extent EMG activity of large number of leg muscles, trunk & shoulder were recorded Patients and controls have similar walking kinematics and with support, walking pattern looks similar But difference in actuators (EMG activity)! |
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How was EMG data from spinal cord lesion patients analyzed and what was discovered? |
PCA ~5 components found that explained variance in data - Components of patients similar to controls Component 1 (describing most variance in EMG data) represents gait cycle Weights determining how much each component explains muscle activity are very different. |
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What underlies human locomotion? |
Limited set of spinal cord pattern generators - Generates cyclic periodic components that integrate sensory inputs & central inputs to oscillatory muscle activity - Brain is only necessary for flexible alterations/feedback functions in locomotion and to increase muscle tone - Sine wave = rough approximation with phase relative to start of gait cycle - Output of the sine-wave generator is responsible of construction of a particular component. - Cycle patterns generated depend on the prefabricated spinal cord machinery |
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How does spinal cord machinery develop from birth to adult hood in terms of principal components? |
EMG patterns recorded from neonates, toddlers & adults to generate kinematic patterns. Principal components needed to generate kinematic profiles are expressed as wave coefficients Adults - 5 PCs exhibited Toddlers and onwards - Similar to adults Neonates - Kinematic patterns very different - No clear role of mature components that characterize walking behaviour - P2 & P4 exist but component 1 & 3 are lacking Conclusion: - Spinal cord pattern generating machinery still premature at time of birth - Machinery is active, but unable to generate full set of normal periodic functions needed for periodic walking - Without central input & sensory feedback from periphery, the generator is confined to default mode where speed is fixed |
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What is further evidence that spinal cord pattern generators are responsible for locomotion in humans? |
Forward & Backwards Walking - Share same kinematic templates - Same planar covariation of segmental movement elements - However, muscle activation patterns (EMG) are different - More muscles activity in backwards walking which is less efficient - Maybe because backwards walking requires more stability because it is unpracticed. |
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What did cat spinal cord lesions tell us? |
Experimental lesion causing "spinal shock" (lack of control of i.e. hind limbs) Cats show same regenerative process as humans (decrease in muscle tone, then increase) - Sensory feedback helps cat to adjust rhythm of hind leg (in absence of CNS) - Suggests locomotion generated in spinal cord mainly |
