A Better Way To Make Mind-Controlled Prosthetic Limbs

the_newsbeagle writes: To make a brain-machine interface, you need a way to capture neurons' electric signals. The most precise and most invasive way uses implants that are stuck in the gray matter. The least precise and least invasive way uses EEG sensors stuck to the scalp. But researchers at Johns Hopkins University say there's a third way that gets the best of both worlds, which is not too invasive and fairly precise. They use ECoG systems, in which a mesh of electrodes is placed under the skull, draped over the surface of the cortex.

They're testing their systems on epilepsy patients, who have these ECoG systems inserted anyway while they're waiting for surgery (the electrodes record the source of their seizures). The researchers are capturing these patients' movement commands from their brains, and using them to control robotic limbs. Someday such a system could be used by amputees to control their prosthetic limbs.

Comments

Not too invasive?

[opusman]

Having anything placed under my skull in direct contact with my brain sounds a little invasive to me.

Re:Not too invasive?

[i kan reed]

I'm going to guess, though I could just be acting like an insensitive clod, that you've never had to deal with the debilitation of a missing limb. I feel like it's going to be a pretty appealing option to a lot of people.

And as far as "invasive surgery" goes, amputations are pretty much top of that category too.

Re:Not too invasive?

[JoeDuncan]

The difference being that the ECoG system appears to simply lay the electrode mesh on top of your cortex, traditional direct neural links involve actually puncturing and penetrating neural tissue with many tiny pins.

Re:Not too invasive?

[Anonymous Coward]

Not that tiny, I did neuroelectrical design for over a decade. Electrodes outside the local motor nerves themselves, have a *ridicious* amount of noise from irrelevant neural material. Even electrodes *on* or in the nerve have ridiculous amounts of noise. And worse, as soon as some fumbfutz tries to digitize and sample it, they throw out most of the data. The signals are not like binary signals, on or off. They're pulse driven. state changes in the right amount, on the right nerves, trigger motion or sensation. The electrical equivalent my monitoring the brain is like monitoring an intersection by listening to the traffic. You've already spent a lot of time gathering information, and by the time you have enough data to be certain of the signal, it's too late and too gross a measurement for detailed mechanical manipulation.

Oh, and the smaller the electrode to help isolate the signals, the more electrical noise you pick up from being stuck in a saline medium, trying to read electrochemical signals in a conductive medium. It's an unavoidable problem until and unless Dr. Rosen's ar some other work succeeds in create an electrode array that transects the nerve and has the nerve cells actually feeding *through* the array.

I'm afraid similar work was done with myo-electric signals to control the original "Boston Arm", which used skin electrodes on the shoulder of the missing arm. The phase delay necessary to sample and collect a valid signal is too large: that's one of the reasons the Boston Arm never became popular.

Mind you, it was cool as futz. I talked to the engineer who did the mechanical design, who actually worked for an insurance company. When I asked him how much it could lift, he said "12 ounces". When I asked him why, he brought his beer bottle to his mouth....

Just wait until they become hackable

[denis-The-menace]

Imagine:
your limb(s) hitting you.
your hand(s) crushing everything.
Your brain getting zapped by the interface.

"good times" are coming.

Re:Just wait until they become hackable

[i kan reed]

Reminder: you're talking about trolling the physically disabled.

Socially, that's usually considered off limits.

Re:Just wait until they become hackable

[preaction]

Have you been to the internet? Do you think anything is off limits?

Re:Just wait until they become hackable

[i kan reed]

Genuinely and honestly, yes.

Re:Just wait until they become hackable

[denis-The-menace]

It is a legitimate concern not brought up in the most tactful way. Anybody in their 20s should push for this because they will have one in 30 years or so. It might even be a job requirement ( https://www.youtube.com/watch?... ) (yup, it still gets hacked in the series)

Just look at what they can do with a CAN-bus in cars today:
https://www.google.ca/search?q...

Now imagine people instead of car. Yup, that's coming. Nothing's off limits.

If it's doable, some asshole will go for it.
Whether it's for kicks or cash.

electrodes take up space in the brain regions

[wherrera]

The only way this could work is if the electrodes can be made much,much thinner than paper thin, and even then they might irritate nearby tissue. It's a huge technical challenge. Better to use a smaller electrode surface area and train the patient to signal to the electrodes.

Re:electrodes take up space in the brain regions

[Rhywden]

Are 76 micrometers thin enough? http://www.nature.com/nmat/jou...

I/O

[Iamthecheese]

I believe brain implants are the human-computer interface of tomorrow. They can offer I/O at speeds and bandwidths limited only by our very elastic brain tissues and the only downsides are the "ick" factor and the fact that we're still learning how to do it safely. For not only virtual limbs but control of any electronic device, typing, cursor movement, and other sensing I say bring it on!

Neurons aren't just in the brain

[king neckbeard]

There are also neurons in the rest of the body. Assuming these are replacement limbs instead of supplementary limbs, why wouldn't they intercae with the neurons the body was previously using to do those communications, e.g., control a replacement hand by connecting it to the neurons in the wrist?

Re:Neurons aren't just in the brain

[sumdumass]

I was wondering the same thing. A possible answer might be that if the limb isn't there long enough, the ability to send the neurons along the proper paths may be lost so capturing them closer to home might be a better solution. Or it could be because the implants are already installed for other purposes in the patients they are studying and getting the control process to work is more important at this stage than how it is eventually used. It could be that they plan on moving the control devices later and taking advantage of the others.

Something else I was thinking about, how long before something like this can control the entire body making it possible for dead people to be artificially resurrected and have a computer installed in the brain. sort of electric zombies or something. Perhaps this will end up with robots being mind controlled also- where an operator thinks about grasping an object in a hazardous area and the robot does so as naturally as a human could via a prosthetic. This might make dangerous situations like entering a burning building or a fukishima type plant disaster easier due to a lot of the controls being created for human interaction verses remote robotics.

Re:Neurons aren't just in the brain

[Mal-2]

Perhaps this will end up with robots being mind controlled also- where an operator thinks about grasping an object in a hazardous area and the robot does so as naturally as a human could via a prosthetic. This might make dangerous situations like entering a burning building or a fukishima type plant disaster easier due to a lot of the controls being created for human interaction verses remote robotics.

You just reinvented the waldo.

Re: Neurons aren't just in the brain

[bugnuts]

Maybe so it can work on those paralyzed from a spinal injury?

I wondered the same thing.

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