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Map of Brain's Speech Centers May Help `Locked-In' Patients Talk

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


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.


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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.

 

 

 

Gary Stix, Scientific American's neuroscience and psychology editor, commissions, edits and reports on emerging advances and technologies that have propelled brain science to the forefront of the biological sciences. Developments chronicled in dozens of cover stories, feature articles and news stories, document groundbreaking neuroimaging techniques that reveal what happens in the brain while you are immersed in thought; the arrival of brain implants that alleviate mood disorders like depression; lab-made brains; psychological resilience; meditation; the intricacies of sleep; the new era for psychedelic drugs and artificial intelligence and growing insights leading to an understanding of our conscious selves. Before taking over the neuroscience beat, Stix, as Scientific American's special projects editor, oversaw the magazine's annual single-topic special issues, conceiving of and producing issues on Einstein, Darwin, climate change, nanotechnology and the nature of time. The issue he edited on time won a National Magazine Award. Besides mind and brain coverage, Stix has edited or written cover stories on Wall Street quants, building the world's tallest building, Olympic training methods, molecular electronics, what makes us human and the things you should and should not eat. Stix started a monthly column, Working Knowledge, that gave the reader a peek at the design and function of common technologies, from polygraph machines to Velcro. It eventually became the magazine's Graphic Science column. He also initiated a column on patents and intellectual property and another on the genesis of the ingenious ideas underlying new technologies in fields like electronics and biotechnology. Stix is the author with his wife, Miriam Lacob, of a technology primer called Who Gives a Gigabyte: A Survival Guide to the Technologically Perplexed (John Wiley & Sons, 1999).

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