Your doctor should be able to incorporate this knowledge into your stroke protocol for spasticity.
So demand that spasticity protocol. Your doctor better have one.
http://www.alphagalileo.org/ViewItem.aspx?ItemId=145983&CultureCode=en
Stretch sensors in our muscles participate in reflexes that serve the
subconscious control of posture and movement. According to a new study published
in the Journal of Neuroscience, these sensors respond weakly to muscle stretch
caused by one's voluntary action, and most strongly to stretch that is imposed
by external forces. The ability to reflect causality in this manner can
facilitate appropriate reflex control and accurate self-perception.
“The results of the study show that stretch receptors in our muscles indicate
more than which limb is moving or how fast; these sensors also adjust their
signals according to who caused the movement,” says Michael Dimitriou, who
conducted this study and is currently a post doc at the Department of
Integrative Medical Biology, Umeå University, Sweden.
Normally, we can easily distinguish between movements we make ourselves and
movements that are imposed on our body by external forces. The ability to
discriminate between self-generated and externally generated sensory events is
crucial for accurate perception and the control of posture and movement. This
ability is also believed to form the foundation on which conscious
self-awareness is built.
Such discrimination between self and other has previously been thought to
arise as a result of complex computations performed in the brain, that use prior
knowledge or memories of the consequences of own actions. But the study by
Michael Dimitriou shows that information on the cause of a sensory effect can be
provided in real-time by so-called ‘muscle spindles’, a class of stretch
receptors found in most of our skeletal muscles.
Muscle spindles differ from other sensory receptors, such as stretch
receptors in the skin, because their sensitivity can be controlled by the
nervous system via specialized motor neurons. The purpose of this control has
been unclear. The neural data presented by Michael Dimitriou indicates that
these specialized motor neurons increase the sensitivity of stretch receptors
when the body is exposed to an externally imposed stretch stimulus, such as when
a falling ball is caught in the hand. Because amplified spindle responses mean
stronger stretch reflexes, the resulting muscle activity instantly counteracts
movement of the hand. When making a voluntary movement, however, the nervous
system ‘automatically’ reduces the sensitivity of spindles in the stretching
muscles, thereby making it possible for us to move without setting off strong
stretch reflexes that would otherwise counteract movement. Uncontrollably strong
stretch reflexes are commonly referred to as ‘spasticity’.
“These results provide an explanation of how reflexes can be functionally
adjusted to help us achieve our everyday tasks, without requiring conscious
control of reflex sensitivity or complex computations in the brain for
predicting the sensory consequences of our actions,” says Michael Dimitriou.
He believes that these new findings are important both for understanding the
neural mechanisms that underlie movement control and self-perception, but also
for understanding pathological states where these mechanisms are disturbed.
“With these findings, we also get new insights into mechanisms whose
malfunction may contribute to neuromuscular problems such as spasticity or alien
hand syndrome (also known as ‘Dr. Strangelove syndrome’), and help identify
potential treatment targets for these conditions,” says Michael Dimitriou.
No comments:
Post a Comment