Brain (journal)

Transcription

Mrs. L was a young-looking sixty-seven year old woman. She was intelligent, but she didn’t know what “singing” meant. And she didn’t hear music like most of us do. In Oliver Saks’ book Musicophilia, Mrs. L described music to sound like pots and pans being thrown around the kitchen. She said that if she went to an opera, it all sounded like screaming. This condition isn’t unique to Mrs. L. About 4% of the population is born with “amusia”. Amusia is a deficit in the brain’s ability to process music. Sometimes it’s called tone deafness, where people can’t differentiate between pitches or distinguish musical notes. In others, amusia can present as beat deafness, the inability to move in time to a musical rhythm. In the worst cases of amusia, people can’t recognise musical information at all. A recent study looked at why beat deaf individuals are unable to keep a beat or tap along with music. (If you’d like to try a bit of the experiment yourself, get ready to tap along). The participants, two beat deaf individuals and a group of control participants, were asked to tap at their own rate, to get an idea of their internal pulse (go on!). Next, they had to listen to a regular auditory beat and tap along with a metronome. Next, they had to tap to a perturbed auditory beat, one with unexpected changes. (How did you do?) Researchers found the beat deaf participants didn’t vary significantly from the control participants when they were tapping at their natural rates. But they performed significantly worse with the auditory beat and the perturbed beat. The process of perceiving the musical beat in their auditory cortex and translating it into motion was broken. We’re not entirely certain about what’s going on inside the brains of those who suffer from amusia; a number of regions are involved in processing music. We do know that the ability to move along to a beat isn’t unique to the human brain. Other species with vocal learning abilities are able to keep a beat--think dolphins, seals, parrots and even cockatoos like Snowball, the YouTube dancing sensation. Snowball was the star participant of a study where researchers played him The Backstreet Boys’ song “Everybody” at different tempos and left him alone in a room to do his thing. It turned out Snowball was baller at keeping a beat at higher tempos; he didn’t respond when the beat was slower. And his head-bobbing moves didn’t imitate any natural movements commonly made by his species of cockatoo in their environment. Snowball was, it appears, really dancing to the beat. And if cockatoos can follow a beat, it’s certainly not out of the question that a small percentage of birds could suffer from amusia , like humans. There’s even been cases where tone-deaf birds can’t recognise a mating call and it disrupts their social structure. Like Mrs. L, the pitch and musical notes just fly over their heads. And if you haven’t already, subscribe to BrainCraft! I have a new episode out every Thursday.