It's not hard to understand why Robert Schumann was selected as the focus of a meeting called The Musical Brain, which took place last weekend in London1. Not only is it the 200th anniversary of the German composer's birth, but his particular 'musical brain' gives neuroscientists plenty to think about.

For one thing, Schumann suffered from the neurological condition called focal dystonia – a loss of muscle control that ended his hopes to be a concert pianist. And he seems also to have struggled with severe bipolar disorder, which apparently dictated the rhythm of his creativity and left him confined to an asylum for the last two years of his life.

Focal dystonia is sometimes called 'musician's cramp', but it's not primarily a muscular problem: it begins in the brain2. As neuroscientist Jessica Grahn of Cambridge University explained, it stems from the way intense musical practice can over-inflate the mental representation of the relevant part of the body (usually the fingers, although it can affect lip control in brass players). Once the neural representations of the fingers overlap, they can no longer be controlled independently.

This typically manifests itself as a painful stiffening or curling-up of some fingers. The American pianist Leon Fleisher lost the use of his right hand in this way in 1963, and only recently returned to regular concert performance. Although dystonia is a consequence of over-practice (or as Fleisher says, inappropriate practice techniques), there may also be a genetic predisposition to it – it's more common, for example, among men. It's precisely because it is a neural rather than a muscle problem that dystonia is so hard to treat, and indeed there is still no genuine cure.

Schumann succumbed to this excruciating condition in his right middle finger at the age of 213. He used a home-made contraption to stretch the finger, but it may have done more harm than good. He even composed an extremely difficult piece, his Toccata Opus 7, that avoids the use of the middle finger entirely. 'I was hoping to convince someone to play it at the meeting', says Grahn, 'but it's a bear, so no luck.'

For poor Schumann, things got even worse. Towards the end of his life, he heard voices and was tormented by visions of angels and demons. In 1854 he attempted to drown himself in the Rhine, only to be rescued by boatmen, whereupon he voluntarily entered an asylum.

Although Schumann's spells of wild creativity and sleeplessness interspersed with periods of lethargy look like a classic case of bipolar disorder, not everyone agrees: some say his mental disturbance could have been caused by syphilis4 or the mercury medication used to treat it. In any event, Schumann is by no means unique among composers in wrestling with mental illness: Mozart, Beethoven, Tchaikovsky and Leonard Bernstein all seem to have done so. But can hear their emotional turmoil in what they wrote?

There's no doubt that music can express intense emotion, which is seemingly one reason why it can be so effective in therapeutic contexts. It was an interest in the use of music in learning and therapy, says music psychologist Katie Overy of Edinburgh University, 'that forced me to get into the emotional aspects'.

While acknowledging that musical expression is multi-faceted, she argues that current neurological studies suggest that the activation of mirror neurons – 'empathy circuits' that fire both when we watch another person perform an action and when we perform it ourselves – offer a clue about how music works5.

It may be, she says, that when we hear music, we can 'read' it as we would read indicators of emotional state in another person's vocal or physical gestures. 'Happy' music is typically up-tempo and high-pitched, while 'calm' or 'sad' music tends to be soft, slow and low-pitched6, because of the way these acoustic qualities mimic the actions and voices of people in those emotional states – an observation that seems to hold across cultures, as Stefan Koelsch of Sussex University, another speaker at the meeting, and his coworkers have shown recently7.

'Music has the capacity to tap into these qualities and expand on them', says Overy. Pianist Ian Brown illustrated during her talk how, for example, musical expressivity can involve mimicry of singing with legato (smoothly connected notes) and speech-like phrasing. The composer and performer can then add to this effect by deploying culture-specific structures (such as major/minor keys) or unexpected rhythms and harmonies: Koelsch showed that musical 'surprises' can elicit the same neurological signals as other types of surprise8.

In this respect, then, support may be emerging for the suggestion of philosopher Susanne Langer that music mimics the dynamics of emotion itself – as psychologist Carroll Pratt put it in 1931, that 'music sounds the way emotions feel'.