Scientists Use Brain Waves to Eavesdrop on the
WEDNESDAY, Feb. 1 (HealthDay News) -- Scientists may one day be
able to read the minds of people who have lost the ability to
speak, new research suggests.
In their report, published in the Jan. 31 online edition of the
PLoS Biology, University of California, Berkeley researchers describe how they have found a way to analyze a person's brain waves in order to reconstruct words the person hears in normal conversation.
This ability to decode electrical activity in an area of the
auditory system called the superior temporal gyrus may one day
enable neuroscientists to hear the imagined speech of stroke or
other patients who can't speak, or to eavesdrop on the constant,
internal monologues that run through people's minds, the
researchers explained in a journal news release.
"This is huge for patients who have damage to their speech mechanisms because of a stroke or Lou Gehrig's disease [amyotrophic lateral sclerosis] and can't speak," Robert Knight, a professor of psychology and neuroscience, said in the news release. "If you could eventually reconstruct imagined conversations from brain activity, thousands of people could benefit."
However, the study's first author, post-doctoral researcher
Brian Pasley, noted that "this research is based on sounds a person
actually hears, but to use this for a prosthetic device, these
principles would have to apply to someone who is imagining
He explained that "there is some evidence that perception and
imagery may be pretty similar in the brain. If you can understand
the relationship well enough between the brain recordings and
sound, you could either synthesize the actual sound a person is
thinking, or just write out the words with a type of interface
For the study, Pasley's team tested two different computational
models that were designed to match spoken sounds to the pattern of
activity in the electrodes when a patient heard a single word. The
better of the two models reproduced a sound that was close enough
to the original word so that the researchers could correctly guess
The aim of the research was to reveal how the human brain
encodes speech, and to then pinpoint the aspects of speech that are
necessary for understanding.
"At some point, the brain has to extract away all that auditory information and just map it onto a word, since we can understand speech and words regardless of how they sound," Pasley said. "The big question is, what is the most meaningful unit of speech? A syllable, [or an even smaller unit of language, such as the sound of each letter]? We can test these hypotheses using the data we get from these recordings."
The American Speech-Language-Hearing Association has more about
adults speech and language difficulties.
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