The rare human can taste their words, quite literally. Now, a group of British scientists is trying to figure out how this unusual cross talk occurs in the brain.
Julia Simner of the University of Edinburgh and Jamie Ward of University College London identified 10 people who can taste words - a sensory experience that is as real to that person as Bolognese sauce over spaghetti sprinkled with hot pepper. Only there is no food. And the word has nothing whatsoever to do with Italy.
Researchers had to travel 9,000 miles around the world to find 10 people who have the rare neurological anomaly that causes it. However rare, unraveling the mystery could yield some very important clues about how the brain regulates sensory information, Simner said.
In a study published in the journal Nature last week, the researchers recount how they designed a study to test the series of neural events that takes place when a person with this syndrome, called synesthesia, sees a word.
To accomplish this, they found unusual objects that people would immediately know but not so easily identify - a platypus, for instance, or castanets. They wanted to elicit a tip-of-the-tongue response so that they could figure out whether the tastes are triggered by the sound of the word or its meaning. Almost 100 unusual words were presented to the subjects, who were then asked about the "taste" that was evoked by the word.
They discovered that tastes are linked to the part of the brain that stores the meaning of the word - and not the sound itself. The taste actually came to the person before the sound, during the search for the word. Words can taste like Caesar salad with too much garlic or hot chocolate.
Simner said that all of the people studied had specific tastes for specific words - and they didn't change over time. (They were re-tested a year later.)
What's happening is that the sensory cross talk - the misfiring of information from one brain region to the next - is leaving the person with the experience of tasting a certain food when he or she hears a word. "It's like an open connection," said Simner, who admitted that it is very frustrating to study synesthesia without being able to experience it herself.
Last year, Swiss researchers also identified a young woman who can taste sounds. She is a musician who can't play a note without a feast of foods filling her taste buds.
Although the taste-word link is rare, scientists say as many as one in 2,000 people may have some other form of more common synesthesia, such as sensing colors when hearing, seeing or reading words, she said.
"Synesthesia is not a mere curiosity," said Dr. Richard Cytowic, a neurologist based in Washington, D.C., who has spent two decades studying the phenomenon.
Researchers said they believe these crossed sensations originate in a primitive region of the brain called the limbic system, associated with behavior and emotion. It is also the relay station for the five senses.
Cytowic, who has written two books on the subject, said it isn't a short-circuit in the system, but perhaps a more primitive mechanism that most people have lost.
