Evidence for a sensitive period in the musical brain

Hello dear reader, I very much hope that your January is going well. We have had some snow here in London which was nice but everyone is getting a little tired of the freezing conditions by now.

This week I am trying to do some testing but it is going very slowly as people are frequently not turning up for sessions (grrrr). One advantage of this is that I have some extra reading time and thanks to this I came across a new paper that is all about the issue of whether there is a ‘sensitive period’ for musical training.

lang langDoes earlier musical training have greater effects on the brain and behaviour? Does that explain why most really amazing musicians, such as Lang Lang and Oscar Peterson, started training when they were very small? Their superior ability could of course be down to the fact that they have just been playing for longer. Does an early start really make a difference?

It seems a lot harder to start musical training as an adult as compared to as a young child. I, for example, tried to teach myself clarinet as an adult and it was a lot harder than when I taught myself to play flute at the age of 12, which was in turn harder than learning the guitar, which I started playing when I was 6. The most common explanation for this is that the brain is more malleable when we are children and just ‘learns faster’ than the adult brain – our mind at this age is more ‘sensitive’ to training.

There is evidence for sensitive periods in other domains such as second language learning and cortical reorganization after early blindness.

Studies of sensitive periods use cross sectional studies, where you compare a population who started training young vs. one who started training later in life.  Evidence already gathered using this technique suggests that musicians who begin earlier show differences in some brain structures; their anterior corpus callosum tends to be larger and there tends to be more extensive representation of motor movements in the cortex. However, no previous study has compensated for the problem that we mentioned right at the start; musicians who start early typically have simply MORE training under their belts – might this explain the differences we find?

A new study by Christopher Steele and colleagues has answered this criticism by pairing two groups of highly trained musicians, one early trainers (ET; began training before the age of 7) and one later trainers (LT; began training after 7). Both groups had around 16 years of experience, meaning of course that the early training group were younger (about 23 vs. 28). There was also a matched group of controls who had minimal musical training experience.

The groups performed a temporal motor sequencing task where they had to tap in synchrony with a ten-note rhythm that was represented visually. They did this task over two consecutive days so the researchers could get a learning score. The researchers then scanned using Diffusion Tensor Imagining (DTI) to identify which white matter regions might differ between the groups.

Steele resultsResults: All 3 groups improved on the tapping task over time. The ETs performed the task better than the LTs, a result which is supported by previous research into synchronisation ability. The DTI data was analysed by looking for unique white matter activation in the ETs that was not present in the LTs or controls. The researchers highlighted a large difference in the posterior midbody/isthmus of the Corpus Callosum.

Once again, the corpus callosum is a region where early musical training makes a difference. The researcher showed that the volume of this area correlated with how long an individual had been training; the earlier people started the larger the difference.

Taken together the evidence suggests that early musical training is associated with larger brain changes and with improved performance on a musical synchronisation test. The authors argue that this data provide evidence for the existence of a sensitive period for musical training – no matter how many years people train, you will find larger differences in this particular brain region in those who begin earlier.

Mri_brain_side_view-emphasizing-corpus-callosumWhat is the corpus callosum and what does it do for a musician, I hear you cry! The corpus callosum (latin for ‘tough body’) is essentially a thick band of nerve fibres right in the middle of the brain that helps to hold the right and left cerebral hemispheres together. It is theorised that the CC allows ‘cross talk’ between the brains two hemispheres.

Particularly important for music is the CC’s potential role in bimanual coordination, very important if you need both hands to play an instrument (most do to some degree). It contains fibres that connect to the sensory motor system and, crucially, undergoes a lot of development between the ages of 6-8.

From this study we can conclude that early musical training (before age 7) has a special impact on the brain which could potentially facilitate musical ability.  However, this study does not say that the ETs are better musicians overall. There is no measure of actual musical performance in the study, other than a quite abstract tapping task.

Armstrong in motionWe must be very careful not to assume that someone who wishes to begin musical training later in life can’t achieve an impressive level of musicality. There are many examples of wonderful musicians who began training as older children or even adults. Louis Armstrong reportedly did not start learning trumpet until his early teens and Andrea Bocelli didn’t start singing opera seriously until the age of 34.

It is important to understand ‘sensitive periods’ but not to be ruled by them. Our brains are capable of music making at any age. 

Paper: Early Musical Training and White-Matter Plasticity in the Corpus Callosum: Evidence for a Sensitive Period by Christopher J. Steele, Jennifer A. Bailey, Robert J. Zatorre, and Virginia B. Penhune. Journal of Neuroscience (2013). 

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