Phantom Melodies Yield Real Clues to Brain’s Workings

I wouldn't be surprised if these elegantly done experiements supporting the theory that "our brains are prediction-generating machines," also applies to those with visual hallucinations and eye disease...

Uvealblues

In 2011, a 66-year-old retired math teacher walked into a London neurological clinic hoping to get some answers. A few years earlier, she explained to the doctors, she had heard someone playing a piano outside her house. But then she realized there was no piano.

The phantom piano played longer and longer melodies, like passages from Rachmaninov’s Piano Concerto number 2 in C minor, her doctors recount in a recent study in the journal Cortex. By the time the woman — to whom the doctors refer only by her first name, Sylvia — came to the clinic, the music had become her nearly constant companion. Sylvia hoped the doctors could explain to her what was going on.

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Dr. Kumar argues that these results support a theory developed by Karl Friston of the Wellcome Trust Center for Neuroimaging. (Dr. Friston is a co-author of the new study.) Dr. Friston has proposed that our brains are prediction-generating machines.

Our brains, Dr. Friston argues, generate predictions about what is going to happen next, using past experiences as a guide. When we hear a sound, for example — particularly music — our brains guess at what it is and predict what it will sound like in the next instant. If the prediction is wrong — if we mistook a teakettle for an opera singer — our brains quickly recognize that we are hearing something else and make a new prediction to minimize the error.

Scientists have long known that people with musical hallucinations often have at least some hearing loss. Sylvia, for example, needed hearing aids after getting a viral infection two decades ago.

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