You Are the Music: How Music Reveals What it Means to be Human (10 page)

A large study of professional pianists carried out at University College London found several areas of the brain where white matter fibres were denser (a greater number of them, better aligned and with more effective myelination
^*
) and moreover this finding was associated with practice; the more someone practised, the denser the white matter. This finding hints at improved connectivity in a number of important brain regions outside the corpus callosum in musicians.

The enhanced connectivity effect is not limited to instrumental learning either. A study conducted by Gus Halwani and colleagues
¹¹
tested the integrity of a particularly large white matter pathway (or ‘tract’) known as the arcuate fasciculus (AF). The AF connects the temporal and frontal lobes and is a very important pathway for carrying information about sound. We have two AF tracts, one in the right hemisphere
and one in the left. Picture this structure as being like a hollow tube filled with rice noodles, which represent the flexible individual fibres within the tract.

Halwani and his team used a technique called tractography to measure the volume (the size of the tube) and the density of the fibres (noodles) in the AF tracts in both hemispheres in non-musicians, instrumental musicians and vocal musicians. The AF tract was larger and denser in musicians compared to non-musicians. Interestingly, in the left hemisphere, parts of the AF were bigger in singers compared to instrumentalists but were also less dense, meaning the fibres in the AF at these points were likely to be more criss-crossed or branching.

Why the difference in the left and right AF in the singers? One theory is that the right AF is more involved in understanding the relationship between sound and how we produce it, through our hands, feet or voices. In contrast, the left AF may be more responsive to how we use our vocal system to produce minute differences in sound. So the left side of the brain may be more focused on the demands of producing speech while the right side is more interested in all types of sound more generally.

The great point about this study is that it hints that you may get a boost effect in brain connectivity from singing, which is something that we can all attempt in our everyday lives without the need for an instrument. Of course, we now need research to establish whether this effect occurs in people who are new to musical training or if it is limited to highly trained musicians.

Movement

If you play a musical instrument or sing then you need to develop complex and delicate motor control skills for optimal performance. The motor feats that top-level musicians can achieve are quite staggering. The best professional pianists can produce up to 1,800 notes per minute while compensating for
tiny changes in volume and pressure, an amazing achievement for the fingers.
¹²
The presence of such incredible motor ability has consequences for the structure of the brain.

People who have developed advanced motor skills for musical performance tend to have measurable differences in the part of the brain that represents the body and its movement. This area sits roughly on the crown of the head, going down towards the brainstem, and comprises the somatosensory cortex and motor cortex. These two structures sit alongside each other and work together very closely.

The motor cortex is in charge of planning and making movements while the somatosensory cortex responds to information about our sensations of touch, including pain, as well as proprioception – our conception of where our body is located in space.

The somatosensory and motor cortices feature a logical, elongated map of the body. This map represents each part of the body to a different degree depending on the importance of fine control and regular use. Your body map would look strange if you were to see it represented visually, an image that has become known as the ‘cortical homunculus’ (see opposite); imagine a person with massive hands, feet, lips, and tongue but a tiny stomach, back, ears and neck.

The brain body map is not the same for everyone of course, as we use our bodies in different ways, and shifts in the map can occur during one person’s lifetime in response to stroke or injury (to either the brain or body). Despite this variety, we can still see general differences between the brain body maps of musicians and non-musicians.

Keyboard musicians show increased tactile sensitivity in their hands
¹³
and perform better on tasks that require motor learning, especially when they have begun musical training early in life.
¹⁴
These traits are backed up by corresponding differences in their brain body map.

Katrin Amunts and colleagues
¹⁵
used MRI to measure a part of the motor cortex where the hands are represented. The researchers found that non-musicians had a more asymmetrical structure, larger on the left compared to the right. This is the expected brain balance for right-handed people since the brain’s representation of our body is crossed over (your right hand on the left side of the brain and vice versa). Keyboard players, by comparison, had a much more symmetrical structure, reflecting a much larger representation of both hands in the brain. This was especially true of people who had started their musical lessons early in life.

More recent studies have also found a more pronounced omega (‘W’ shaped) pattern in the motor cortex of musicians
¹⁶
. Amazingly, the effects in that study were identified just by looking at the brain with the naked eye – the differences are that clear to see.

Scientists have also looked at responses in the brain’s body map. Christo Pantev and colleagues
¹⁷
studied string players who had all begun their musical training at a young age and who were still practising regularly and compared them to a group of control participants who did not play an instrument or carry out other rhythmic activity with their fingers such as typing. The researchers stimulated the participants’ thumb and little fingers on both hands with a little harmless, painless pressure. They then measured the cortical response in the somatosenory areas using a magnetoencephalography (MEG) scanner, a sensitive piece of equipment that measures brain activity by recording the magnetic fields around the head that occur in response to electrical currents.

Pantev and his colleagues found larger brain responses in musicians compared to the non-musicians but only in the left hand, indicating that the representation of movement in the fingers was larger in the musicians’ brains. The fact that this effect was larger in the left hand was probably driven by
the large number of violin players in the study, who use their left hand for much finer movements than their right (bow) hand.
¹⁸

These studies tell us that musicians’ skills in fine motor control have consequences for the way that they perform on non-musical motor tasks in the lab, and that this difference shows up in the structure and activity of the brain body map that in some places you can actually see with the naked eye.

Listening skills

In the previous chapter on music in childhood we saw that one of the first changes to the brain that occurs following music lessons is a boost in hearing skills – you may recall the phrase ‘music for a smarter ear’. By adulthood we can clearly see the anatomical and functional differences in the brains of musicians who by the stage of adulthood are masters at perceiving and responding to small changes in sound, especially on their instrument/voice.

Activation levels in the primary auditory cortices of professional musicians in response to musical sound have been found to be 102 per cent larger than in non-musicians only 30 milliseconds after the onset of a tone. Furthermore, grey matter in parts of auditory cortex has been found to be 130 per cent larger.
¹⁹
Musicians also show enhanced perception of small music- and speech-like changes.
²⁰
It is fair to say that musicians’ brains are big, quick and powerful when it comes to analysing sounds.

One important point about musical experience is that it is not simply a ‘volume knob effect’
²¹
where everything gets better. Neural responses to sound are balanced to leave more resources available for processing complex aspects of sound, which professional musicians can do better. The boost that occurs in auditory processing in musicians is in that sense an optimising process.

One of the consequences of this optimisation process is that you see the biggest boosts in processing familiar sounds – a musician’s own instrument or voice – as compared to other sounds. Christo Pantev and his team demonstrated that musicians get an increased brain response (25 per cent larger) in the first milliseconds after hearing a musical tone.
²²
No such boost occurred when musicians heard ‘pure tones’, artificial pitch sounds that a traditional instrument would never produce. (These tones are composed of all the basic elements of a sound wave – frequency, wave length and amplitude – so we hear pitch but without any of the overtones that arise from natural vibration of air caused by a piano string or a clarinet reed.)

In a second study Pantev compared the brain responses of violin and trumpet players to violin and trumpet tones.
²³
The researchers measured the strength of the cortical response to the tones and found a clear pattern – a bigger boost for the more familiar instrument in both groups.

Most recently, Dana Strait and colleagues have demonstrated a similar pattern of results when looking at very early brainstem responses.
²⁴
When exposed to sounds, the brainstem emits a wave signal in response, as a result of the electrical activity in the brain, which is called an auditory evoked potential. Think of it as being like the echo of your voice when you shout into a cave. The brainstem response can be measured to determine the extent to which it is similar to the original sound, in the same way that you could record an echo and compare it to your original shout.

Strait and her colleagues recorded auditory brainstem responses in pianists and non-pianists (all accomplished adult musicians) as they listened to three different musical sounds: 200 milliseconds of piano, bassoon or tuba. The pianists’ auditory brainstem response to piano sound more closely resembled the characteristics of the sound wave compared to the
brain responses of other musicians. In essence, the pianist’s brains produced a more accurate looking brain ‘echo’ of their own instrument. In the paper the authors refer to this effect succinctly as the production of a more accurate ‘neural snapshot’ of piano sound in pianists.

All these findings suggest that the brain tunes its auditory system to a fine level, giving the musician a natural advantage when it comes to listening to music by their own instrument or voice. This likely occurs as a result of the stimulation of feedback and feedforward pathways in the brain as a musician strives to learn from their own sound and push the fine-tuning of their own performance for maximum effect.

This apparent blessing can also be a curse, however, as it puts trained musicians at a disadvantage if they are listening to their own instrument when it is slightly out of key. I have personal experience of this phenomenon, as very slight mis-tunings of the guitar used to drive me mad when I was judging competitions. This baffled me at the time as I knew that I was nowhere near as sensitive to the sound of other instruments, even though I was an avid music listener. Now I know why!

The enhancement in hearing skills that we see in musicians can get quite specific but you can also see general effects. One such effect is the processing of pitch in speech. Patrick Wong used the auditory brainstem recording technique to look at responses to Mandarin Chinese tones in musicians and non-musicians.
²⁵
He found improved pitch tracking within the brain response in musicians who did not speak Chinese, even though they were listening to linguistic tones as opposed to musical ones. The musicians’ tracking of the linguistic pitch was more robust and faithful. This finding may explain in part why musicians are often better at learning to speak a second language.
²⁶