Last May, a 34-year-old paralysed man was able to drink from a cup unaided using a robotic arm that he controlled with a brain implant. Brain implants are becoming more sophisticated — they can allow the deaf to hear, the blind to see, and stave off the debilitating effects of neurological illnesses like Parkinson’s.
All of these technologies are made possible by brain implants: electrical devices inserted into or attached to the brain. These implants have sensors or electrodes that can monitor activity, block or electrically stimulate processes in the neural network.
Applying these technologies to already-healthy people may even give us superpowers by enhancing our senses. Brain implants may be able to help people sharpen focus and improve moods, and external brain stimulation has already shown some success in helping people learn maths faster.
But implants right now require invasive surgery, and are often made of steel or other metals that cause scarring. Brain implant technology is hampered by how long implants can stay in the brain without causing damage or losing functionality.
A game-changing implant
Now a tiny new brain implant makes two big strides in this technology: It can be injected directly into the brain from a syringe, minimising damage to brain tissue and can be applied without invasive surgery.
Not only that, but the flexible mesh imitates the interconnecting structure of the neural network and the softness of brain tissue, and is made of materials that the immune system is less likely to reject, so it seems to create less scarring in the brain when it has been inserted.
That’s important because when the body detects one of today’s brain implants, the brain tissue surrounds the foreign object with scar tissue, causing it to malfunction. The scarring can also cause damage and neuron loss in the area where the implant sits.
The researchers described the innovation in the journal Nature Nanotechnology on June 8. They were able to inject the mesh into the brains of anesthetized mice through a tiny hole in the skull and record brain activity with electrodes and sensors on the mesh.
“If you look at implanted electronics in the brain over the past 10 to 20 years, all suffer from a common problem,” said study author Charles Lieber, of Harvard University. “Electronic probes, in research and in medicine, create scarring in brain tissues. There’s a mismatch if they’re stiff and this leads to an immune response… [they are] not stable over time.”
How it works
The incredibly small mesh implant has “very fine metal lines” of circuitry embedded, with electrodes and sensors mounted at the intersections of the wires. By curling the flexible implant, the researchers were able to fit a 1.5 centimeter wide square of mesh up into a syringe with an opening less than half a millimetre wide.
Once injected into the brain, the mesh unfolds to about 80% of its original shape without loss of function. The external wires of the mesh can then be plugged to a computer to monitor and stimulate individual neurons.
Lieber said the secret to the immune system’s acceptance of the implant is because of its flexible and open structure. Up to 95% of the mesh is open space, allowing individual neurons to communicate with adjacent neurons uninterrupted. The implant’s design was inspired by another 2012 study published in Nature Materials where Lieber was able to grow cells on a tiny mesh-like scaffold.
“The idea was this material is an open structure… which allows the three dimensional interconnection of the brain to work right, and without doing massive surgery,” he said.
The study showed that the mesh didn’t trigger an immune response in a five-week period after injection.
The future of brain implants
Lieber hopes that this mesh might someday be used in humans to treat neurological illness or brain damage caused by strokes, but said the next step is to test it for a longer period of time, maybe up to a year.
“We’re up to three months so far in this ongoing study,” he said. “There’s been no change in the response and it still has good recording behaviour, unlike other devices where they either lose the signal or there is so much scarring over time that you have to move the implant’s position.”
If the implants are successful they would be a better option for people who get long-term implants to treat the symptoms of Parkinson’s Disease.
This treatment, called deep brain stimulation, delivers stimulation from implants to regulate the electrical misfirings in the brain that cause these involuntary movements. But like many implants, the probes used in deep brain stimulation can trigger the development of scar tissues.
Developing long-term implants that don’t get rejected by the immune system could pave the way to using the technology for enhancement, rather than just treatment. Artist Neil Harbisson has an antenna implanted that treats his colorblindness, but it allows him to experience colour in a way that no one ever has — he says he can hear it.
The implanted antenna detects colours and assigns a tone to each colour, allowing Harbisson to “hear” colour through bone conduction.
This type of enhancement might be common in just a few more years. The Defence Advanced Research Projects Agency is already working on brain implants that could restore memories and treat brain damage. Having a brain implant to remember facts would greatly enhance our abilities to take tests and perform everyday work.
That might be possible in the future, when tiny brain implants can give us abilities that extend beyond our biological limits. Ray Kurzweil believes we’ll able to access the internet with our minds using DNA nanobots in just 15 short years.
As brain implants shrink and become safer, that might not be such a crazy prediction.
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