Speed Of Thought-to-speech Traced In Brain

In just 600 milliseconds, the human brain can think of a word, apply the rules of grammar to it and send it to the mouth to be spoken. For the first time, researchers have traced this lightning-fast sequence and broken it down into distinct steps.

Researchers got this rare glimpse into the fine-tuned workings of the brain from the signals sent by electrodes implanted in the brains of epileptics. The electrodes help surgeons locate the parts of the brain that cause epileptic seizures so they can be removed, and also help keep surgeons from removing critical parts of the brain

"If you go a few millimeters to the right or left, you might delete their piano lessons or language ability, and that would be sorely missed," said Ned Sahin of Harvard University, one of the researchers who studied the language network.

Because the electrodes are already monitoring language ability in these patients, Sahin and his colleagues can conduct simple language experiments with willing participants and see language processing in real time; essentially, the electrodes offer a more fine-grained look at neural processes than other traditional brain-monitoring technologies, such as MRIs.

The language center

The main brain region Sahin and his colleagues looked at is called the Broca's area, located in the cerebral cortex. This region was discovered to be involved in language processing by the French physician Pierre Paul Broca in 1865.

But beyond knowing that the area is important to language production, "we still have been troublingly unable to pin it down," Sahin said. Whether or not the steps of the language production process happen in parallel or sequentially has been one particularly puzzling question about the brain.

The new electrode study, detailed in the Oct. 16 issue of the journal Science, has set scientists one step closer to understanding the steps of language production in the brain, specifically word recall, the application of grammar (changing tense or number), and actually speaking the word.

By monitoring the brains of three patients while,

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