Wednesday, September 19, 2012

The Importance of Practice and Sleep for Musicians - Molly Gebrian

Musicians v. Non-Musicians - Molly Gebrian

Most of studies on changes in neuronal activity only last a week or two at the most. 

It’s not logistically feasible to have people coming into the lab for weeks or months on end to have their brains looked at, so, some neuro-scientists think musicians are an ideal population to find out what happens when you practice a motor task repeatedly for years and years.

One of the most obvious changes is that, especially in string players and keyboard players, the portion of the motor cortex devoted to the fingers is much bigger.

At the same time, the neurons in this cortical network are much more efficient.

These two things happen because, presumably, over time, lots and lots of neurons get connected by synapses that wouldn’t normally be connected, and the neuronal ensembles that result from these new connections get much better at what they do because they get to practice everyday.

A musician’s brain is so efficient at things like scales and other simple patterns that are automatic to us that entire brain areas don’t get engaged in a musician’s brain that are very active in a non-musician or amateur’s brain.

Two of these areas are the pre-motor cortex and the supplementary motor area.

These are involved in planning complex movements and coordinating timing, but when musicians play scales or simple rhythm patterns, these areas barely do anything at all.

The only other complex motor tasks that show this lack of activation are overlearned skills such as writing.

What this means is that our basic set of tools and skills as musicians are so automatic that our brain barely has to do anything to execute them.

But what this also means is that when you learn a new skill, especially something like the extended techniques used in contemporary music, there is a necessary period of days or weeks that your brain needs to rewire itself and for new neuronal ensembles and circuits to form.

The other amazing thing that happens in musicians’ brains, as new synapses form, is that our motor cortex gets connected to our auditory cortex.

Think about how strange that is. For most people, what they hear doesn’t cause them to have automatic associations with movement, and moving certainly doesn’t cause them to hear things in their heads.

But if a musician listens to a recording of a piece they know and play well, not only does their auditory cortex light up on a brain scan (fMRI), but the portion of their motor cortex devoted to their fingers does too.

Furthermore, neuroscientists have shown that the motor cortex isn’t just lighting up as a whole unit – the areas that control the individual fingers light up in the order and timing they would to execute the correct fingering (Bangert and Altenmuller, 2003).

NB: When these kinds of studies are done, measures are taken to make sure the musicians aren’t physically moving their fingers.

The opposite happens too: if you tell a pianist to play a piece silently on a tabletop, their auditory cortex lights up as it would if they were actually playing (and hearing) the piece.

These finding just serve to highlight how important it is to always keep singing in your head as you play and to be really clear about what you want to hear.

It affects what comes out of your fingers and arms and mouth, not in some strange metaphysical way, but because your auditory cortex is connected to your motor cortex.

If you aren’t clear on what you want to hear, the auditory cortex has a very limited message to send to your fingers.

The Role of Sleep in Learning

If all of these changes have to take place in your brain before you can play something fluidly and competently, is there anything you can do to speed up the process?

The answer depends on how much you want to speed it up, because it turns out that a very important component of motor (and auditory) learning is sleep.

Matthew Walker and his colleagues here in Boston have done a number of experiments on motor learning during sleep (Walker, et al, 2002, 2003, 2005).

Their basic experimental paradigm involves three groups of people. The first group gets taught a finger tapping task (4-1-2-3-4 where 4 is the pinky finger and 1 is the index finger) at 10am, which they then practice and are tested on multiple times throughout the day.

The second group gets taught and practices the same task at 10am, but they don’t get tested on it again until 10pm.

Then, they are sent home to sleep and tested the next morning at 10am. The final group is trained on the task at 10pm and has their first retest at 10am the next morning. What they found is astonishing.

The first group gets gradually better throughout the day at a rate that you can predict.

The second group shows the same linear increase during the day, but when you test them the next morning, there is a huge jump in their performance (measured by faster sequence execution without loss of accuracy).

The same goes for the group that was trained at 10pm and then retested for the first time the next day – they got much better overnight, even though all they were doing was sleeping!

NB: Everyone was instructed not to practice when they went home.

Even more surprising, there is absolutely no relationship between how much better a person got during daytime practicing and how much better they got after sleeping.

How is this possible and what does it mean? Researchers have concluded that the last result means that practice-dependent learning and sleep-dependent learning are independent processes.

This doesn’t mean, of course, that if you don’t practice, you’ll get better just by sleeping but it does mean that you shouldn’t underestimate the importance of sleep in learning, especially when it’s brand new.

Knowing this can help you use your practice time much more efficiently.

Say, for instance, you have a lot of music to learn for orchestra and not a lot of time to practice it.

You will be much better off practicing your orchestra music for 15 minutes a day until the concert, rather than “wood-shedding” the day before the concert.

Why? Because you’ll have all those nights of sleep for your brain to process the new music. So ultimately, you’ll be able to play the music better with fewer hours of actual practice.

When you’re learning a new piece that you have ample time to practice, keeping the role of sleep in mind can also help you practice more efficiently.

The primary thing that improved with sleep for the people in these studies was speed (at least that’s what the experimenters were measuring).

Since the amount of daytime improvement and learning after sleep aren’t related, spending hours and hours on a really tricky fast passage on the first few days of practicing isn’t as efficient as getting it fluent at a slower tempo and then just leaving it until the next day.

The next day, not only will you be able to play it faster, but you’ll spend much less time getting it to a faster tempo than you would’ve the day before.

No one probably would’ve guessed that just sleeping would make you better at playing your instrument, but researchers have shown that it does, over and over again.

The effects of sleep are really hard to study, but in this case, researchers think they know how it works.

Sleep is divided into two broad types: REM sleep and non-REM sleep (or NREM sleep). REM sleep is when you have dreams.

During what is called Stage 2 NREM sleep, however, electrical brain events occur that are called sleep spindles.

During a sleep spindle, there is a huge burst of electrical activity in a population of neurons that causes massive amounts of calcium to enter those cells.

Calcium is what causes all the changes discussed earlier, from strengthening and weakening synapses, to making new synapses, to synchronizing the firing of neuronal ensembles.

Sleep spindles reach peak intensity late in the night and have been shown to increase following motor learning during the day.

The study by Matthew Walker and his colleagues at Harvard Medical School also found that the percentage of improvement after sleeping strongly correlated with the amount of time the person spent in Stage 2 NREM sleep in the final quarter of the night, precisely when sleep spindle activity is at its peak.

This finding also highlights the importance of getting enough sleep while you’re learning something new.

A full night of sleep was defined as 8 hours in this study, and it was only the last two hours that were really important for learning.

Getting a full night’s sleep may be even more important that we realize.

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