The New York Times published an interesting article:

"Neuron Network Goes Awry, and Brain Becomes an IPod "

Seven years ago Reginald King was lying in a hospital bed recovering from bypass surgery when he first heard the music.

It began with a pop tune, and others followed. Mr. King heard everything from cabaret songs to Christmas carols. "I asked the nurses if they could hear the music, and they said no," said Mr. King, a retired sales manager in Cardiff, Wales.

"I got so frustrated," he said. "They didn't know what I was talking about and said it must be something wrong with my head. And it's been like that ever since."

Each day, the music returns. "They're all songs I've heard during my lifetime," said Mr. King, 83. "One would come on, and then it would run into another one, and that's how it goes on in my head. It's driving me bonkers, to be quite honest."

Last year, Mr. King was referred to Dr. Victor Aziz, a psychiatrist at St. Cadoc's Hospital in Wales. Dr. Aziz explained to him that there was a name for his experience: musical hallucinations.

Dr. Aziz belongs to a small circle of psychiatrists and neurologists who are investigating this condition. They suspect that the hallucinations experienced by Mr. King and others are a result of malfunctioning brain networks that normally allow us to perceive music.

They also suspect that many cases of musical hallucinations go undiagnosed.

"You just need to look for it," Dr. Aziz said. And based on his studies of the hallucinations, he suspects that in the next few decades, they will be far more common.

Musical hallucinations were invading people's minds long before they were recognized as a medical condition. "Plenty of musical composers have had musical hallucinations," Dr. Aziz said.
Read the full article here.

Should make for an interesting read.