What is the brain up to when we listen to music? Until recently that question had to be answered indirectly, for example by using psychological tests or in particular by seeing how damage to or dysfunction of particular areas of the brain affect a person’s experience of music. Some of these deficits are quite general—a small proportion of the population (much smaller than you probably think) is genuinely tone-deaf, unable to process pitch properly and therefore to hear the difference between one note and another. But other cognitive problems are remarkably, even bizarrely specific. There are people who, because of damage to their brain, have become unable to blend several notes together into a harmonious chord, or who can hear music perfectly well but can’t identify familiar tunes, or who have developed an obsession for polkas.
Recently, medical imaging techniques such as MRI and PET scanning have made it possible to look inside the brain: to see which bits of it we use when we listen to music. These are still somewhat crude tools—even if a part of the brain comes to life, for example, we can’t be sure precisely what it is doing. But these methods are supplying important clues about our mental processing, for example by showing that music may activate a part of the brain known to be involved in language processing, or parts that deal with emotion and reward, or parts that connect to our muscle movements. One clear message from this work is that music can be a gymnasium for the mind, able to stimulate perhaps more different functions than any other activity we know of.