A Flexible Circuit Has Been Injected Into Living Brain
by Devin Powell / June 8, 2015
What if the next gadget for sending messages to your friends wasn’t a watch strapped to your wrist or a phone stuffed in your pocket—but an electronic device embedded in your brain? Now, a new kind of flexible circuit has brought us one step closer to this science fiction future. Implanted via injection, a grid of wires only a few millimeters across can insinuate itself with living neurons and eavesdrop on their chatter, offering a way for electronics to interface with your brain activity. “We’re trying to blur the distinction between electronic circuits and neural circuits,” says Charles Lieber, a nanotechnologist at Harvard University and co-author of a study describing the device this week in Nature Nanotechnology. So far the tech has been tested only in the heads of live mice. But Lieber hopes to ultimately wire it up to humans. His backers include Fidelity Biosciences, a venture capital firm interested in new ways to treat neurodegenerative disorders such as Parkinson’s disease. The military has also taken an interest, providing support through the U.S. Air Force’s Cyborgcell program, which focuses on small-scale electronics for the “performance enhancement” of cells.
Neural electronics are already a reality for some people. Those suffering from severe tremors or uncontrollable muscle spasms can find relief via electric shocks, which are delivered by long wires threaded deep into the brain. And quadriplegics have learned to control prosthetic limbs using chips embedded in the brain or electrodes laid on the brain’s surface. But these technologies can only be used in severe cases because they require invasive procedures. “Previous devices have relied on large incisions and surgeries,” says Dae-Hyeong Kim, a nanotechnologist at the Seoul National University in South Korea. What makes the new approach different is the circuit’s exceptional pliability. Made from strands of metal and plastic woven together like fishing net, the circuit is a “hundred thousand times more flexible than other implantable electronics,” says Lieber. The net can be rolled up so that it can easily pass through a syringe needle. Once inside the body, the net unfurls of its own accord and becomes embedded in the brain. Autopsies of injected mice revealed that the wires had woven themselves into the tangled fabric of neurons over the course of weeks. Tight connections formed as plastic and brain matter knitted together with seemingly little negative impact. This compatibility is perhaps because the net was modeled after three-dimensional scaffolds used by biomedical engineers to grow tissues outside of the body.
The neurons’ activities could be monitored using microscopic sensors wired into the circuit. Voltage detectors picked up currents generated by individual brain cells firing. Those electrical signals were relayed along a wire running out of the head to a computer. “This could make some inroads to a brain interface for consumers,” says Jacob Robinson, who develops technologies that interface with the brain at Rice University. “Plugging your computer into your brain becomes a lot more palatable if all you need to do is inject something.” For neuroscientists interested in how brain cells communicate, this sensitive tool offers access to parts of the nervous system that are difficult to study with traditional technologies. Three months ago, for instance, a colleague of Lieber’s injected some of his nets into the eyes of mice, near nerve cells that gather visual information from the retina. Probing those cells typically requires cutting out a chunk of the eye. Signals collected by the injected nets have remained strong so far, and the mice remain healthy.
To be useful for humans, though, Lieber’s team will need to prove that the nets have even greater longevity. Previous neural electronics have suffered from stability problems; they tend to lose signal over time as cells near the rigid intruders die or migrate away. But the team is optimistic that Lieber’s mesh will prove to be more brain-friendly, since cells encountering it so far seem to cuddle up and grow into its gaps. Listening in on brain activity may be only the beginning—as with everyday circuits, different components can be added for different tasks. In another experiment, Lieber’s team injected circuits outfitted with pressure sensors into holes inside a soft polymer. When the polymer was squeezed, the sensors measured changes in pressure inside the cavities. That could be useful for investigating pressure changes inside the skull, such as those that occur after a traumatic head injury.
Further down the line, the net may be studded with feedback devices that deliver electrical stimulation or release packets of drugs for medical treatment. Add in a few microscopic RFID antennae, and the circuit could go wireless. And sci-fi fans should salivate at the thought of installing memory storage devices—similar to the RAM inside computers—to improve their own memories. “We have to walk before we can run, but we think we can really revolutionize our ability to interface with the brain,” says Lieber.
The rise of brain-computer interfaces
by Elizabeth Armstrong Moore / Dec. 2, 2014
In 2012, a paralyzed woman with a 96-electrode sensor the size of a baby aspirin implanted onto the surface of her brain was able to think about steering a robotic arm toward a canister with a straw in it, move the canister toward her mouth, tilt it so the straw fell into her mouth, and take a sip. It was the first time in 15 years that the woman, who was one of two patients doing experiments with the BrainGate implant, had picked up anything, let alone served herself a beverage, and the look on her face when she finished said it all. “There was a moment of true joy, true happiness,” John Donoghue, the neuroscientist who pioneered the BrainGate implant a decade ago, said in a Brown University video. “It was beyond the fact that it was an accomplishment … it was really a moment where we helped somebody do something that they had wished to do for many years.”
It was a seminal moment in the relatively new world of brain-computer interfaces, where neuroscientists and engineers are working on building implants and robotic limbs and even entire exoskeletons to allow people whose movements are limited by spinal cord injuries, or Parkinson’s disease, or strokes to override these physical limitations and have their brains communicate directly with machinery instead. Now more than 10 years into the BrainGate project, Donoghue’s team has moved from working with monkeys who used their thoughts alone to move cursors and play primitive video games to enabling actual people to engage with their surroundings, and with considerable success. (The 53-year-old woman known as S3 touched her intended target within a set time nearly 50 percent of the time using one robotic arm and 70 percent of the time using another, while a second patient known as T2 produced nearly identical results.) Lee Miller, a neuroscience professor at Northwestern University, has been enjoying some success as well with his project: implanting tiny multielectrode arrays in monkeys to help them grasp, lift, and drop a ball. These arrays are programmed to detect the activity of just 100 neurons to read the signals that lead to hand movements, even though as many as a million are involved.
“We are capturing a very impoverished amount of the motor ability humans are capable of,” he said, “so even though we could get the monkey to reach out and grasp the ball with reasonable dexterity, there is no way the monkey would be playing the piano.” Miller’s research builds on similar work out of the University of Washington that, back in 2008, used an algorithm based on the activity of just 12 neurons to get monkeys to bypass paralysis by controlling their muscles using these “artificial” connections, as bioengineer Eberhard Fetz told me. “The brain controls normal muscles and the brain computer interface simply picks up these control signals in the brain and activates artificial muscles or artificial limbs,” Fetz said. “So instead of controlling with our fingers, we control it with the cells that control our fingers.”
Other teams around the world are looking to take brain-machine interfaces further – from controlling helicoptersto controlling the expression of our very DNA. Miguel Nicolelis, a neuroscience professor at Duke, is hailed by many as one of the true pioneers in the field of brain-computer interfaces. He was the first to both propose and demonstrate that animals (including humans) can control prosthetic devices via brain-machine interfaces, and his development of what are called chronic, multisite, multielectrode recordings is behind scientists’ ability today to measure the activity and interactions of large populations of single neurons in the brain. Nicolelis’ Walk Again project was on one of the world’s biggest stages this past summer when a 29-year-old paraplegic in a metal vest and a blue cap dotted with electrodes kicked off the World Cup in Nicolelis’ native Brazil. The man used his own thoughts to control the neuroscientist’s exoskeleton. Nicolelis told CNN at the time that the kick was meant to “shock the world,” and added: “[One day] we’ll be walking in New York and we’ll see a person walking on the streets that could not walk before. I think in our lifetime we’ll see that.”
These are still the early days. The sheer volume of neurons in the brain is so large, and the complexity so mind boggling, that researchers in the fields of neuroscience and neurorehabilitation are celebrating every baby step forward, including the simple grasping and lifting of objects – and so are the participants themselves, for whom these actions represent life-changing advances. “I remember once we were discussing the project with several potential participants,” Donoghue of BrainGate told The New York Times in 2010. “‘Would you like to walk again?’ someone asked an interested candidate. ‘No, I’d just like to be able to scratch my own nose,’ he answered.”
Brain-to-brain interfaces: the science of telepathy
by Kristyn Bates / March 8, 2015
“Recent advances in brain-computer interfaces are turning the science fantasy of transmitting thoughts directly from one brain to another into reality. Studies published in the last two years have reported direct transmission of brain activity between two animals, between two humans and even between a human and a rat. These “brain-to-brain interfaces” (BBIs) allow for direct transmission of brain activity in real time by coupling the brains of two individuals. So what is the science behind this? Brain-to-brain interface is made possible because of the way brain cells communicate with each other. Cell-to-cell communication occurs via a process known as synaptic transmission, where chemical signals are passed between cells resulting in electrical spikes in the receiving cell. Synaptic transmission forms the basis of all brain activity, including motor control, memory, perception and emotion. Because cells are connected in a network, brain activity produces a synchronised pulse of electrical activity, which is called a “brain wave”.
Brain waves change according to the cognitive processes that the brain is currently working through and are characterised by the time-frequency pattern of the up and down states (oscillations). For example, there are brainwaves that are characteristic of the different phases of sleep, and patterns characteristic of various states of awareness and consciousness.
Brainwaves are detected using a technique known as electroencephalography (EEG), where a swimming-cap like device is worn over the scalp and electrical activity detected via electrodes. The pattern of activity is then recorded and interpreted using computer software. This kind of brain-machine interface forms the basis of neural prosthesis technology and is used to restore brain function. This may sound far-fetched, but neural prostheses are actually commonplace, just think of the Cochlear implant!
The electrical nature of the brain allows not only for sending of signals, but also for the receiving of electrical pulses. These can be delivered in a non-invasive way using a technique called transcranial magnetic stimulation (TMS). A TMS device creates a magnetic field over the scalp, which then causes an electrical current in the brain. When a TMS coil is placed over the motor cortex, the motor pathways can be activated, resulting in movement of a limb, hand or foot, or even a finger or toe. Scientists are now working on ways to sort through all the noise in brainwaves to uncover specific signals that can then be used to create an artificial communication channel between animals. The first demonstration of this was in a 2013 study where a pair of rats were connected through a BBI to perform a behavioural task. The connection was reinforced by giving both rats a reward when the receiver rat performed the task correctly. Hot on the heels of this study was a demonstration that a human could control the tail movements of a rat via BBI.
We now know that BBIs can work between humans too. By combining EEG and TMS, scientists have transmitted the thought of moving a hand from one person to a separate individual, who actually moved their hand. The BBI works best when both participants are conscious cooperators in the experiment. In this case, the subjects were engaged in a computer game. The latest advance in human BBIs represents another leap forward. This is where transmission of conscious thought was achieved between two human beings in August last year. Using a combination of technologies – including EEG, the Internet and TMS – the team of researchers was able to transmit a thought all the way from India to France. Words were first coded into binary notation (i.e. 1 = “hola”; 0 = “ciao”). Then the resulting EEG signal from the person thinking the 1 or the 0 was transmitted to a robot-driven TMS device positioned over the visual cortex of the receiver’s brain. In this case, the TMS pulses resulted in the perception of flashes of light for the receiver, who was then able to decode this information into the original words (hola or ciao). Now that these BBI technologies are becoming a reality, they have a huge potential to impact the way we interact with other humans. And maybe even the way we communicate with animals through direct transmission of thought. Such technologies have obvious ethical and legal implications, however. It is important to note that the success of BBIs depends upon the conscious coupling of the subjects.”
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