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Map of Brain’s Speech Centers May Help “Locked-In” Patients Talk

The views expressed are those of the author and are not necessarily those of Scientific American.


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Electrode placement on speech motor cortex

Wilder Penfield’s famous homonculus map of the brain had a large area on one side capped by a gaping cartoon mouth labeled simply “vocalization.”

During the 1930s,  Penfield stimulated that same area, but was unable to elicit any recognizable utterances. A group of researchers led by Edward F. Chang of the University of California San Francisco has now had better luck. The team captured brain activity from the sensorimotor cortex of three epilepsy patients undergoing surgery who were asked to pronounce syllables like “bah,” “dee,” and “goo.”

Recording with dozens of electrodes, Chang and colleagues produced a detailed map of the areas in the cortex that activate the anatomical structures involved with speech and also chronicled the synchronized firing of neurons in the various speech centers.  “What wasn’t known was how these populations of neurons were coordinated,” Chang says. “It turns out that this question is a very critical one for understanding how speech works. The vocal tract is sort of like an orchestra where you have individual players like the lips, the tongue the jaw, what we call articulators. Speech arises from the coordination of  these  players.” The research was published in the Feb. 20 Nature.

Neural codes, the electrical signals from the cortex that engage the vocal tract,  could, in theory, be used one day as inputs to an artificial speech synthesizer for “locked-in” patients unable to speak—a still elusive goal of brain-machine technology researchers.

Image source: Nature Publishing Group

NOTE: A correction was made to Penfield’s first name.

 

 

 

About the Author: Gary Stix, a senior editor, commissions, writes, and edits features, news articles and Web blogs for SCIENTIFIC AMERICAN. His area of coverage is neuroscience. He also has frequently been the issue or section editor for special issues or reports on topics ranging from nanotechnology to obesity. He has worked for more than 20 years at SCIENTIFIC AMERICAN, following three years as a science journalist at IEEE Spectrum, the flagship publication for the Institute of Electrical and Electronics Engineers. He has an undergraduate degree in journalism from New York University. With his wife, Miriam Lacob, he wrote a general primer on technology called Who Gives a Gigabyte? Follow on Twitter @@gstix1.

The views expressed are those of the author and are not necessarily those of Scientific American.





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