Implanted Brain Grid Reads Minds

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Implanted Brain Grid Reads Minds

Accurately gathers motor signals to let people control machines

Betterhumans Staff

6/10/2004 3:28 PM

An implanted brain grid has been found to accurately read motor signals, a step

towards using it for thought-controlled wheelchairs and prosthetics.

The grid, studied by researchers at Washington University in St. Louis, uses

electrocorticographic (ECoG) activity rather than electroencephalographic (EEG)

activity, the latter of which is commonly used to study the brain.

This gives it a higher resolution and broader bandwidth, allowing for faster and

more accurate mind reading.

" To put this in perspective, " says researcher Leuthardt, " the previous

EEG-based systems are equivalent to a 1908 brothers airplane in regards

to speed of learning to achieve control. Right now with our results we're flying

around in an F-16 jet. "

While better than EEG in many ways, ECoG requires taking data invasively

directly from the brain.

Leuthardt and colleagues therefore tested the system on four people with

epilepsy who had ECoG implants so that doctors could find brain regions

responsible for their seizures.

While waiting for a seizure so that their brain could be measured, the patients

consented to being connected to a computer linked to the ECoG grid.

The researchers then asked them to perform motor and speech tasks—such as

moving their hands, talking and imagining—and used this to correlate parts of

their brain to movements.

They then asked the patients to play a simple computer game in which they moved

a cursor up or down towards one of two targets.

By imagining movements or imagining saying the word " move, " the patients were

able to control the cursor with thought alone.

" We closed the loop, " says researcher Moran. " After a brief training

session, the patients could play the game by using signals that come off the

surface of the brain. They achieved between 74 and 100% accuracy, with one

patient hitting 33 out of 33 targets correctly in a row. "

The researchers say that the system is faster to learn than those using EEG.

" It takes many months to train using EEG, whereas our approach was done

basically in an hour or so, " says Moran. " That's because we got the signals from

the surface of the brain rather than having to go through the skull. "

The researchers next aim to have patients try 2D games and to implant ECoG grids

into monkeys to see how long they derive reliable data.

The long-term goal is to create a brain-machine interface that lasts at least a

decade, making it practical to implant such a system to allow new types of

prosthetics for people who are paralyzed.

" We are pretty confident that we can get signals from these for many years, "

says Moran. " There will have to be a rigorous study on monkeys for an

indeterminate number of years before we can consider permanent implants in human

subjects, but we're really excited about this advance. "

The research was reported in the Journal of Neural Engineering.