Sensorimotor Models Flashcards
Limitations of the vicious cycle?
Some studies show increased muscle activity. Other studies show decreased or no change. Clinical improvement has been seen with no change in muscle activity suggesting possible cognitive aspects rather than motor adaptation.
What is the pain adaptation model (lunds)?
Changes in voluntary movement argue in activity of muscle that is painful is uniformly inhibited and he antagonist is facilitated
Limitations of lunds pain adaptation model?
Combinations of reduced and increased muscle activity have been shown in dynamic movements of the leg.
Some study on mastoid process muscles showed increased excitability innverating both painful muscle and antagonist.
Constant force pain vs no pain can be maintained.
What does hodge propose as a new model instead of vicious cycle and lunds model?
That there is activity within and between muscles that is redistributed,
Changes mechanical behaviour such as modified movement and stiffness that leads to protection from further pain or injury,
is not explained by simple excitation but multiple levels of motor system that can be complementary, additive or competitive.
Has short term benefit but potential long term consequence due to increased load, decreased movement and variability.
How is constant force mainteind despite inhibitation of some motor units in states of induced pain?
- Distribution of activity between abdominal muscles with experimental back pain showing obliques to become more responsive.
- Force output maintained by recruitment of additional units that were not active during contractions without pain.
Voluntary reflex control of human back muscles during induced pain study was for what purpose?
To examine the motor output of the erector spinae muscles during pain in the lumbar region.
What theories did the flexion relaxation study test?
Lunds theory and vicious cycle theory.
What is the flexion relaxation phenomenon
Any pain from the lumbar structures causes muscles to tense and not relax
What is meant by pain mode? What does it explain?
Es contraction protecting any injured structure deep somatic thus absence of relaxation in back muscles at full flexion. Protects spine from deep movement without distinguishing the tissue of origin.
What evidence supports/refutes the stretch reflex as a mechanism for increased activity?
Deep muscle pain didn’t change the reflex at all, pain in muscle itself had no effect on the stretch reflex. It was only cutaneous pain that had an effect on sr.
What might explain the decreased activation observed extension?
May reflect voluntary avoidance of pain and belief of pain in strong muscle contract. Or segmental inhibibition by nociceptive input of descending voluntary commands to motoneurons.
What changes were observed during trunk flexion?
Even though pain on the right there was some influence of the other Es. Pain spread from one side to the other, maybe overloaded. Overall the left Es was deprived, like the right Es of relaxation to the same extent,
What is the vicious cycle theory?
Increase in activity of painful muscles which induces ischemia from vascular compromise. Becoming the source of further pain by accumulating pain metabolites.
