Thursday, 21 June 2012

A Pilot Experiment to Aid Musician's Cramp

We have all had the uncomfortable experience of involuntary eye twitching, eye lid tics or muscle spasm. Gemma Correll is a professional illustrator who often refers to these eye twitches in the series of her daily diaries, attributing them to stress, fatigue or too much caffeine intake.

Illustration belonging to Gemma Correll's daily diaries where she explains an episode of eye twitching.
 Image posted with permission of Gemma Correll 

For professionals who rely on fine motor skills such as athletes or musicians, suffering from regular and consistent muscle twitches can have a great impact in their performance and truncate their careers. Traditionally these twitches have been linked to performance anxiety, or to lack of training, but increasing evidence is pointing that it is produced by faulty neural connections. What might have started as involuntary muscle twitches or muscle incoordination could be symptoms of a complex neurological movement disorder called dystonia. According to the  Dystonia Society it is estimated that only in the UK there are over 70,000 people suffer from this condition of which 8,000 are children. 

Focal dystonia can present itself as task specific, for example when writing (writer's cramp) or when playing an instrument (musician's cramp). It is estimated that 1% of professional musicians suffer from musician's cramp. 

Gemma Correll posing next to a mural she has painted. Image posted with permission from Gemma Correll
Dr Mark Edwards from the Institute of Neurology at University College London is currently piloting an experiment using transcranial direct current stimulation (TDCS) and transmagnetic cranial stimulation (TMS) to target faulty neural connections in musicians who suffer from focal hand dystonia. 

"There are musicians out there who are struggling and giving up their careers because of dystonia" Mark explains. 


Dr Mark Edwards in the Institute of Neurology, showing an old model of TMS with one coil

So are musicians relieved to learn that they have a medical condition rather a psychological condition? 


"That’s true, it speaks to the overlap they are told that it has to do with performance anxiety, which is not exactly true. What it is true is that musicians with dystonia tend to have higher levels of anxiety who musicians who do not have dystonia.



It is a very interesting interphase, but in society as soon as something is psychological, there is a sense that it is something that you are doing yourself and that you could snap out of it, as if it is something not real, and that you are weak. Psychological conditions are also generated by the brain, so it would be quite surprising that if the brain went wrong it wouldn’t have an impact on those aspects too. It is a matter of trying to explain to people that cognitive psychological issues are involved, so treatment can help".


What do we know today about dystonia? 

"The strongest theory is that dystonia is a product of abnormal brain plasticity. There are children who have dystonia that affects their whole body and adults that only have eye and head muscles affected, previously they were classified as different conditions when we know today that they are the same condition"

Nobody is born a professional music player, it takes years of practice and learning in order to play an instrument well. "Practice makes perfect", learning to do something new eventually gets easier and performance improves after training and repetition. The neural connections in the brain of the student have to undergo changes to establish a new skill, this capacity is called brain plasticity



Brain plasticity refers to any change in the neural system, from learning to aging, from memorizing to adapting to brain damage. Brain plasticity is the result of the formation of new connections between neurons or from changes in the strength of those connections. The strength and effectiveness of a neural connection is both activity and experience dependent. The more a neural connection is in use the more efficient it will become. This implies that the more you train doing something the better you get at it.   



Hence the phrase of the 1906 Nobel Prize winner Ramon y Cajal "All man can be, if it is his purpose, be the sculpturer of his own brain".



Professional musicians present an adaptive plastic reorganization of the neural connections in the motor and sensory cortical areas in the brain which are responsible for the coordination and muscle movements required to play an instrument. This allows musicians to perform precision movements at higher speed than a normal individual can do. The activation of the neural command to move a finger will trigger the inhibition of movements of the fingers next to it, so the musician can aim precisely at a note and not at another.

Photo of the modern model of TMS with two coils 

What happens in the brain of musicians with dystonia?

"In case of the musicians, they have pushed that particular body part to an extreme, which is the way your motor system changes, but in vulnerable people to this dystonia, this system is set in a different way, it is more sensitive, so these changes trigger complexity in the neuronal communication producing a spill over of muscle control".

Musician's cramp affects different muscles depending on the instrument that is played, for example violinists and pianists may present problems with finger, hand or arm movement, and wind players frequently present tongue or lip coordination problems. Because the prevalence of musician's cramp is not equivalent among all the distribution of instrumental groups this condition might be triggered by certain movements.

Musician playing the cello. In order to avoid copyright problems, image taken from wikipedia

Why musician's who have dystonia don't improve when training?  The more you practice the more efficient those particular neural connections should be.

"TMS stimulation protocols can induce plastic changes in the motor cortex, but when they are applied to individuals that have dystonia they show that their brain plasticity is affected. The excitation gets spread outside, so areas which are topographically near get excitation as well". 

"We don’t really know how plasticity works in abnormal situations, so TMS can help us understand how the brain works in these conditions". 

"With a simple associative thing, if you are playing the piano and you want to move one finger, the excitation in the motor cortex makes you move the finger next to it, so you might not play the note that you are aiming for. Your linking sensations with movement, you are thinking that you are doing a specific movement when actually the excitability is spreading to other muscles of nearby".

Prokofiev and Rostropovich. Image taken from wikipedia
So it’s a problem of balance between excitatory and inhibitory connections?

"Yes. Dystonia as a group they don’t have enough activity of their inhibitory circuits, so you can show that at cortical level, spinal cord level, brainstem level. There is a loss of inhibitory control. This was the idea but it seems that the problem is more complex. When observing people with dystonia caused by genetic problems, it is quite common to find people that carry the genetic mutation but do not have dystonia, they also have a similar loss of inhibition but they are clinically unaffected. So the argument is that the loss of inhibition is not enough".

Surround inhibition

"When moving just one finger, the contractions of the muscles are never really isolated, the whole forearm and hand also have certain degree of muscle contractions, to produce a fine movement, some degree of control over the excitability over these body parts is needed. When you are doing a small movement with one finger, the excitability of the surrounding fingers is reduced. People who suffer from focal hand dystonia seem to loose this surround inhibition, so the muscles from the neighbor fingers also contract" Mark explains.

The nervous system is capable of generating focused neural activity through a physiological mechanism called surround inhibition. Surround inhibition or lateral inhibition seems to result from a general organization pattern in neural connectivity, where excitatory neurons are surrounded by local inhibitory neurons, so the activation of one area also produces the inhibition of the neighboring areas.

The cytoarchitectonic structure of the mammal brain cortex presents a matrix of excitatory and inhibitory neurons. Mice cortex. Stained in green are pyramidal neurons which are excitatory and on the back stained in red, GABA-ergic neurons which are inhibitory.  Image taken from wikipedia.


People who suffer from dystonia show an abnormal surround inhibition, where activation of certain motor commands produce an involuntary activation of other movements resulting in poor motor control. The abnormal surround inhibition observed in the motor cortex might be derived by abnormal motor signals coming other motor regions in the brain, such as the basal ganglia.


Pilot treatment of hand dystonia targeting muscles


Surround inhibition is also present in sensorimotor interaction, so moving one finger while stimulating adjacent fingers enhances surround inhibition. Mark and his team have applied this protocol to people who suffer from hand dystonia.


"A postdoctoral researcher Dr Panagiotis Kassaveti has studied nerve periphery issues in dystonia. He has given subjects stimulation in the surrounding muscle spindles at the same time they were performing the task related to their dystonia. The effect was short lived, but the surrounding inhibition of these subjects was enhanced improving their symptoms".

Dr Mark Edwards with a TMS (unplugged) device.

Pilot treatment of hand dystonia targeting the cerebellum.

Mark and his team are targeting faulty neural connections in the cerebellum that underlie the involuntary muscle twitches and block them with TDCS while the musicians are playing their instrument. Mark and his team expect that this protocol will allow the system to form a new adaptive neural network.


"When you are playing an instrument you are recalling a memory of the motor pattern necessary to play that instrument. During recollection, the memory becomes vulnerable to change. That is the basic idea", Mark says. 


Mark's first subject, a classic guitarist whos hand dystonia has affected his career, reported some mild shortlived benefit from the TDCS treatment. Encouraged by this, Mark and his team are working on a longer TDCS treatment that could produce changes in the long term.  


"We are currently doing a pilot, the first subject reported benefit after applying a stimulation protocol to his cerebellum. We might have found a effect but it is still short lived. We need to start running proper placebo controls" Mark explains.


"We don’t really know how plasticity works in abnormal situations, so TMS can help us understand how the brain works in these conditions".

Dr. Andrew Spence ( see previous post) who works in robots says that the cockroach is able to move better than any other robot that the NASA has been capable of designing ...

"If you think about robots and artificial intelligence, they can learn how they can play chess but when it comes to basic motor skills, they can hardly perform simple motor movements. 

In the video of the final of the robots playing football, the States against Japan, which is the pinnacle of technology, they display such a low level of performance when compared to a professional football player like Ronaldinho. Ronaldinho's skills are beyond what a robot can ever do".





I would like to thank Mark Edwards for his time and for sharing his work with the curious neuron's readers, and hope his pilot treatment can aid musician's with dystonia.  I would also like to thank Gemma Correll for letting me publish her work in this post. Without them this post wouldn't have been possible.

References

Altenm├╝ller E, Baur V, Hofmann A, Lim V.K., Jabush H.C. "Musician's cramps as a manifestation of maladaptative brain plasticity: arguments from instrumental differences" Ann N YAcad Sci. 2012 Apr; 1252:259-65.

Beck S and Hallet M "Surround inhibition in the motor cortex" Exp Brain Res 2011; 210:165-172. 

Berlucchi G and Butchel H.A. "Neuronal plasticity: historical roots and evolution of meaning" Exp Brain Res 2009; 192:07-319

Edwards MJ, Talelli P,  Rothwell JC "Clinical applications of transcranial magnetic stimulation in patients with movement disorders". Lancet Neurol 2008; 7: 827–40

Galea JM,Vazquez A, Pasricha N, Orban de Xivry J.J. And Celnik P. “Dissociating the roles of the cerebellum and motor cortex during adaptative learning: the motor cortex retains what the cerebellum does” Cereb Cortex 2011;21:1761-1770

3 comments:

  1. He is the best creative person today. After seeing this website http://gemmacorrell.com/ any web designer would be shocked with the work. Sample Contracts

    ReplyDelete
  2. that is so much good work nice to see all these things.. bestkreative thanks for sharing..

    ReplyDelete
  3. Oh that's great information you have to sharing everyone! and i appreciate for you thanks for sharing! BestKreative

    ReplyDelete