from the University
of Utah have found a way for severely paralyzed humans to
with their thoughts" through the use of microelectrode
implants on top of the brain.
signals of paralyzed people can be translated into words through the
use of two grids of 16 microelectrodes which are implanted above the
brain and beneath the skull. But unlike many other types of
electrodes, these microelectrode implants are much smaller than
traditional electrodes developed half a century ago and they don't
penetrate the brain at all -- they simply sit on top of it. These
microelectrodes are called microECoGs, and their ability to work
without penetrating the brain makes them safer for speech areas of
the brain, which cannot be said for penetrating electrodes up to this
microelectrode implants work
by placing the microECoGs, each spaced 1 millimeter apart, on two
different speech areas of the brain: the facial motor cortex and the
Wernicke's area. The facial motor complex controls movement of the
lips, mouth, tongue and face while Wernicke's area is a "little
understood" area in the brain that is linked to language
understanding and comprehension.
Greger, an assistant professor of bioengineering and lead author of
this study, along with his team, tested the use of the
on a volunteer with severe epileptic seizures. They were
able to place the implants between the brain and the skull due to the
volunteer's previous craniotomy, which is the temporary partial
removal of the skull in order to locate and surgically stop the
and his team then placed the microelectrodes on the man's brain and
had him repeatedly read 10 words that would be useful to him while
his brain signals were recorded. The words were repeated 31 to 96
times, and were “yes”, “no”, “goodbye”, “hello”,
“more”, “less”, “hot”, “cold”, “hungry”, and
“thirsty”. After recording the volunteer's brain signals, the
team then went to figure out which brain signals represented which of
the 10 words.
comparing brain signals for words like "yes" and "no"
or "hot" and "cold," Greger and his team were
able to recognize brain signals for each word 76 to 90 percent of the
time. When all 10 brain signals were compared at once, it was a bit
more difficult. The team could only correctly match a signal with a
word 28 to 48 percent of time, but Greger argues that these numbers
are still better than chance, which is 10 percent.
is proof of concept," said Greger. "We've proven these
signals can tell you what the person is saying well above above
chance. But we need to be able to more with words with more accuracy
before it is something a patient really might find useful."
though this new method requires a lot of improvement before it can be
used in clinical
trials, Greger and his team did find some interesting results,
such as the fact that Wernicke's area is more involved in high-level
understanding of language and that the team was able to distinguish
signals for one word from those for another 85 percent of the time
when signals were recorded from the facial motor complex. When
recorded from Wernicke's area, they were only able to distinguish
signals 76 percent of the time.
obvious next step - and this is what we are doing right now - is to
do it with bigger microelectrode grids," said Greger. "We
can make the grid bigger, have more electrodes and get a tremendous
amount of data out of the brain, which probably means more words and
study was published in the Journal
of Neural Engineering this
quote: "New smaller, impenetrable microelectrodes could help paralyzed patients communicate safely"