What’s the News: Scientists have built a brain implant that can restore lost memories and reinforce new ones. The implant, tested in a recent study in rats, brings back a memory by recording and replaying the electrical activity of neurons in a part of the hippocampus, the brain’s long-term memory center. While the device is far from ready for use in humans, it’s an important step toward memory-boosting implants that could one day help patients who have developed dementia or suffered a stroke.
What’s the News: Engineers and patients dream of mechanical prosthetic limbs that can talk and listen to the brain, moving in response to thought and sending back sensory information. For that dream to become reality, electrodes from the prosthetic have to connect with nearby nerve cells—a tricky proposition, given that nerve cells in an amputated limb won’t grow without proper structural support. A new tubular scaffold, described in detail by Technology Review, has tiny grooves that fit bundles of nerve cells, which could provide the support nerves need to interface with a mechanical limb better than current designs.
What’s the News: Scientists have discovered a new technique for linking semiconducting tubes with mouse nerve cell tendrils: They let the cells do the work for them. After creating biologically friendly semiconductor tubes, they found that nerve cells’ tendril-like axons didn’t shy away. “They seem to like the tubes,” University of Wisconsin-Madison biomedical engineer Justin Williams told Science News. This represents a step toward new technology involving computer-brain networks.
How the Heck: The trick was to create tubes of layered germanium and silicone (which insulate the nerve’s electrical signals) that were big enough for the nerve cell’s threadlike projections to enter but too small for the cell body: When seeded with live mouse nerve cells, the only way the cells could interact with the tubes was be sending tendrils into it—which is just what they did.
What’s the Context:
Not So Fast: The researchers don’t yet know whether the connected nerves are actually talking with each other.
Next Up: Now they want to hook the tubes to voltage sensors that can “listen” to the cells communicating with each other. If successful, this could lead to new drug tests where doctors can actually measure how nerve cells respond to certain types of drugs, leading to further innovations in the battle against neurological diseases like Parkinson’s.
Image: Minrui Yu, University of Wisconsin–Madison
Reference: “Semiconductor Nanomembrane Tubes: Three-Dimensional Confinement for Controlled Neurite Outgrowth” Minrui Yu et al. DOI: 10.1021/nn103618d
From Carl Zimmer:
Deep in your brain there are probably several thousand neurons that will respond only to the sight of Lady Gaga. Several thousand others probably only crackle to the sight of Justin Bieber. It might be nice to reassign those neurons to loftier thoughts. For now, though, neurology can’t help you. What neurology can do for you (if you’re up for a little invasive brain surgery) is let you use those Gaga and Bieber neurons to control a computer.
A team of researchers has built on the previous discovery that specific neurons respond to the images of specific people–like Lady Gaga, or your grandmother. To harness these neurons, the researchers tried out an ingenious brain-machine interface based on images of celebrities who triggered particularly strong responses in 12 patients.
A patient could bring a digital image of a celebrity (like Marilyn Monroe) into the foreground by consciously focusing on the image, which meant that the celebrity-associated neurons were firing. As they describe in a paper in Nature, the patients quickly got the hang of it, activating patches of neurons at will. This has led researchers to wonder if people could one day control devices simply by visualizing certain people, things, or concepts.
You can get the rest of the story on this fascinating but intrusive technology, and can also see a video that Carl made about the experiments, at The Loom.
DISCOVER: Can a Single Neuron Tell Halle Berry From Grandma Esther?
80beats: New Treatment Lets Paralyzed Rats Walk Without Using Their Brains
80beats: Researcher Updates His Twitter Feed Using Only Brainwaves
80beats: Honda’s Mind-Controlled Robot Could Be Your Avatar in the Real World
80beats: Monkeys Use a Electronic Brain Interface to Move Paralyzed Limbs
Image: Moran Cerf and Maria Moon
Scientists recently used treadmill exercise, drugs, and electrical stimulation to train paralyzed rats to walk once again, demonstrating a way to possibly treat spinal injuries in humans, which at present are basically untreatable.
In a spinal injury, the neural circuits connecting the brain to the muscles that control walking become damaged or severed, leaving an individual paralyzed. In able-bodied people, these “walking circuits” spring into action when they receive a signal from the brain, but if the spinal cord is damaged, the message from the brain never arrives. When contact with the brain is lost, the circuits shut down [The Guardian]. In the study, published in Nature Neuroscience, researchers manipulated these circuits and produced movement that was “almost indistinguishable” from normal walking. See for yourself in the embedded video.
Yesterday, Honda Research Institute revealed the latest trick from its Asimo robot: It can now respond to commands issued only as thoughts. The Japanese carmaker ran a video of a man imagining four simple movements – raising his right hand, raising his left hand, running and eating – that were then duplicated by Asimo, the company’s humanoid robot. Honda said the technology was not ready for a live demonstration because the test subject might get distracted. A previous demonstration in 2006 required the test subjects to lie motionless in an MRI scanner in order to pick up the signals [Financial Times].
The mind-reading system is non-invasive, meaning that the controller doesn’t have electrodes implanted in his head. Researchers used a specialized helmet instead, which is the first “brain-machine interface” to combine two different techniques for picking up activity in the brain. Sensors in the helmet detect electrical signals through the scalp in the same way as a standard EEG (electroencephalogram). The scientists combined this with another technique called near-infrared spectroscopy, which can be used to monitor changes in blood flow in the brain [The Guardian]. A software program then integrates the two signals and transmits a command to the robot.
Deep brain stimulation can now be used to treat obsessive compulsive disorder, or OCD, which causes uncontrollable worries and anxiety in its sufferers. Medtronic‘s Reclaim deep-brain stimulation (DBS) device received approval from the Food and Drug Administration after a study of 26 patients with severe OCD that showed a 40 percent reduction in symptoms after a year of deep brain stimulation therapy. All the patients had tried and failed other therapies [Chicago Tribune].
The Reclaim device is implanted under the skin of the chest and then connected to four electrodes in the brain. The electrodes deliver steady pulses of electricity that block abnormal brain signals [AP]; the device is controlled by a battery-run component outside the body. Hooman Azmi, a neurosurgeon at Hackensack University Medical Center, said, “This is essentially like a pacemaker for the brain” [WebMD Health News].
In a new experiment, researchers didn’t have to ask their test subjects whether they’d prefer coffee or tea; instead, they just read their minds. With a nifty bit of technical wizardry, researchers beamed near-infrared light at the volunteers’ foreheads while asking them to mentally decide which of two beverages they liked better. By examining how the light was absorbed by the volunteers’ brain tissue, researchers were able to predict a person’s preference with 80 percent accuracy.
Lead researcher Tom Chau says he hopes a similar device can one day help people with severe cerebral palsy or neuromuscular conditions that keep them paralyzed in unresponsive bodies. “Basically their mind is alert,” he said. “This is kind of the compelling argument behind the work, that these individuals are cognitively capable – they’re aware of their surroundings, they understand what’s going on – but they have no means of communicating their intentions or preferences to the outside world” [Canadian Press].
Coauthor Sheena Luu adds that the device could use simple preferences to build up to larger decisions and thoughts. “If we limit the context – limit the question and available answers, as we have with predicting preference – then mind-reading becomes possible” [The Register], she says.
IBM has won a $4.9 million government grant from DARPA to begin the first phase of research on “cognitive computing”– essentially building computers that work like living brains. The new brain-like computers will aim to process vast amounts of data to solve problems without relying on specific programmed algorithms. Mark Dean, Vice President of IBM said, “The challenge is that computers today are very good at computing, but what we really need is a more efficient way of sifting through information” [International Herald Tribune].
The inside of computers already have the look of neural networks, a static road map of electronic circuits. But the brain actually works by constantly creating, breaking, and tweaking the synaptic connections between neurons. Although today’s computers may excel at complex challenges with clear rules, like chess, they fail at simple tasks that require strategy, sensation, perception, and learning, like finding misplaced keys. IBM will partner with five universities to develop new nano-scale circuitry that has the ability to shift depending on the signals that pass through them. Free from the constraints of explicitly programmed function, computers could gather together disparate information, weigh it based on experience, form memory independently and arguably begin to solve problems in a way that has so far been the preserve of what we call “thinking” [BBC].