Posts Tagged ‘control’

Three Men Receive Bionic Hands Controlled With Their Minds

The outlook used to be pretty bleak for those who had lost movement in their limbs due to severe nerve damage, but over the last year or so, some incredible advances have been made that are restoring shattered hope for many.

The amazing breakthroughs include spinal cord stimulation that allowed paralyzed men to regain some voluntary control of their legs, a brain implant that enabled a quadriplegic man to move his fingers, and a system that allowed a paralyzed woman to control a robotic armusing her thoughts. Science has definitely been on a roll, but this winning streak isn’t showing any signs of slowing down. Now, the world’s first “bionic reconstructions” have been performed on three Austrian men to help them regain hand function. This technique enabled the newly amputated patients to control prosthetic hands using their minds, allowing them to perform various tasks that most people take for granted.

The men that underwent the procedure had all suffered serious nerve damage as a result of car or climbing accidents, which left them with severely impaired hand function. The nerves that suffered injury were those within a network of fibers supplying the skin and muscles of the upper limbs, known as the brachial plexus. As lead researcher Professor Oskar Aszmann explains in a news release, traumatic events that sever these nerves are essentially inner amputations, irreversibly separating the limb from neural control. While it is possible to operate, Aszmann says the techniques are crude and do little to improve hand function. However, his newly developed procedure is quite different, and is proving to be a success.

Before the men could be fitted with their prosthetic hands, the researchers had to do some preliminary surgical work in which leg muscle was grafted into their arms in order to improve signal transmission from the remaining nerves. After a few months, the fibers had successfully innervated the transplanted tissue, meaning it was time to start the next stage: brain training.

Using a series of sensors placed onto the arm, the men slowly began to learn how to activate the muscle. Next, they mastered how to use electrical nerve signals to control a virtual hand, before eventually moving on to a hybrid hand that was affixed to their non-functioning hand. After around nine months of cognitive training, all of the men had their hand amputated and replaced with a robotic prosthesis that, via sensors, responds to electrical impulses in the muscles.

A few months later, the men had significantly improved hand movement control, which was highlighted by a test of function known as the Southampton Hand Assessment Procedure. As reported in The Lancetbefore the procedure, the men scored an average of 9 out of 100, which soared to 65 using the prosthetic. Furthermore, the men reported less pain and a higher quality of life. For the first time since their injuries, they were able to perform avariety of tasks such as picking up objects, slicing food and undoing buttons with both hands.

“So far, bionic reconstruction has only been done in our center in Vienna,” said Aszmann. “However, there are no technical or surgical limitations that would prevent this procedure from being done in centers with similar expertise and resources.”

The above story is adopted from The Lancet and reprinted from materials provided by NewScientist.

Researchers Partially Control a Memory

Scripps Research Institute Team Wrests Partial Control of a Memory

The work advances understanding of how memories form and offers new insight into disorders such as schizophrenia and post traumatic stress disorder.

Scripps Research Institute scientists and their colleagues have successfully harnessed neurons in mouse brains, allowing them to at least partially control a specific memory. Though just an initial step, the researchers hope such work will eventually lead to better understanding of how memories form in the brain, and possibly even to ways to weaken harmful thoughts for those with conditions such as schizophrenia and post traumatic stress disorder.

The results are reported in the March 23, 2012 issue of the journal Science.

Researchers have known for decades that stimulating various regions of the brain can trigger behaviors and even memories. But understanding the way these brain functions develop and occur normally—effectively how we become who we are—has been a much more complex goal.

“The question we’re ultimately interested in is: How does the activity of the brain represent the world?” said Scripps Research neuroscientist Mark Mayford, who led the new study. “Understanding all this will help us understand what goes wrong in situations where you have inappropriate perceptions. It can also tell us where the brain changes with learning.”

On-Off Switches and a Hybrid Memory

As a first step toward that end, the team set out to manipulate specific memories by inserting two genes into mice. One gene produces receptors that researchers can chemically trigger to activate a neuron. They tied this gene to a natural gene that turns on only in active neurons, such as those involved in a particular memory as it forms, or as the memory is recalled. In other words, this technique allows the researchers to install on-off switches on only the neurons involved in the formation of specific memories.

For the study’s main experiment, the team triggered the “on” switch in neurons active as mice were learning about a new environment, Box A, with distinct colors, smells and textures.

Next the team placed the mice in a second distinct environment—Box B—after giving them the chemical that would turn on the neurons associated with the memory for Box A. The researchers found the mice behaved as if they were forming a sort of hybrid memory that was part Box A and part Box B. The chemical switch needed to be turned on while the mice were in Box B for them to demonstrate signs of recognition. Alone neither being in Box B nor the chemical switch was effective in producing memory recall.

“We know from studies in both animals and humans that memories are not formed in isolation but are built up over years incorporating previously learned information,” Mayford said. “This study suggests that one way the brain performs this feat is to use the activity pattern of nerve cells from old memories and merge this with the activity produced during a new learning session.”

Future Manipulation of the Past

The team is now making progress toward more precise control that will allow the scientists to turn one memory on and off at will so effectively that a mouse will in fact perceive itself to be in Box A when it’s in Box B.

Once the processes are better understood, Mayford has ideas about how researchers might eventually target the perception process through drug treatment to deal with certain mental diseases such as schizophrenia and post traumatic stress disorder. With such problems, patients’ brains are producing false perceptions or disabling fears. But drug treatments might target the neurons involved when a patient thinks about such fear, to turn off the neurons involved and interfere with the disruptive thought patterns.

Notes about this memory research article

In addition to Mayford, other authors of the paper, “Generation of a Synthetic Memory Trace,” are Aleena Garner, Sang Youl Hwang, and Karsten Baumgaertel from Scripps Research, David Rowland and Cliff Kentros from the University of Oregon, Eugene, and Bryan Roth from the University of North Carolina (UNC), Chapel Hill.

This work is supported by the National Institute of Mental Health, the National Institute on Drug Abuse, the California Institute for Regenerative Medicine, and the Michael Hooker Distinguished Chair in Pharmacology at UNC.


Source: The Scripps Research Institute press release

Original Research: Abstract for “Generation of a Synthetic Memory Trace” by Aleena R. Garner, David C. Rowland, Sang Youl Hwang, Karsten Baumgaertel, Bryan L. Roth, Cliff Kentros & Mark Mayford in Science

Human Thought Can Voluntarily Control Neurons in Brain

Neuroscience research involving epileptic patients with brain electrodes surgically implanted in their medial temporal lobes shows that patients learned to consciously control individual neurons deep in the brain with thoughts.

Subjects learned to control mouse cursors, play video games and alter focus of digital images with their thoughts. The patients were each using brain computer interfaces, deep brain electrodes and software designed for the research.

Controlling Individual Cortical Nerve Cells by Human Thought

Five years ago, neuroscientist Christof Koch of the California Institute of Technology (Caltech), neurosurgeon Itzhak Fried of UCLA, and their colleagues discovered that a single neuron in the human brain can function much like a sophisticated computer and recognize people, landmarks, and objects, suggesting that a consistent and explicit code may help transform complex visual representations into long-term and more abstract memories.

Now Koch and Fried, along with former Caltech graduate student and current postdoctoral fellow Moran Cerf, have found that individuals can exert conscious control over the firing of these single neurons—despite the neurons’ location in an area of the brain previously thought inaccessible to conscious control—and, in doing so, manipulate the behavior of an image on a computer screen.

The work, which appears in a paper in the October 28 issue of the journal Nature, shows that “individuals can rapidly, consciously, and voluntarily control neurons deep inside their head,” says Koch, the Lois and Victor Troendle Professor of Cognitive and Behavioral Biology and professor of computation and neural systems at Caltech.

The study was conducted on 12 epilepsy patients at the David Geffen School of Medicine at UCLA, where Fried directs the Epilepsy Surgery Program. All of the patients suffered from seizures that could not be controlled by medication. To help localize where their seizures were originating in preparation for possible later surgery, the patients were surgically implanted with electrodes deep within the centers of their brains. Cerf used these electrodes to record the activity, as indicated by spikes on a computer screen, of individual neurons in parts of the medial temporal lobe—a brain region that plays a major role in human memory and emotion.

Prior to recording the activity of the neurons, Cerf interviewed each of the patients to learn about their interests. “I wanted to see what they like—say, the band Guns N’ Roses, the TV show House, and the Red Sox,” he says. Using that information, he created for each patient a data set of around 100 images reflecting the things he or she cares about. The patients then viewed those images, one after another, as Cerf monitored their brain activity to look for the targeted firing of single neurons. “Of 100 pictures, maybe 10 will have a strong correlation to a neuron,” he says. “Those images might represent cached memories—things the patient has recently seen.”

The four most strongly responding neurons, representing four different images, were selected for further investigation. “The goal was to get patients to control things with their minds,” Cerf says. By thinking about the individual images—a picture of Marilyn Monroe, for example—the patients triggered the activity of their corresponding neurons, which was translated first into the movement of a cursor on a computer screen. In this way, patients trained themselves to move that cursor up and down, or even play a computer game.

But, says Cerf, “we wanted to take it one step further than just brain–machine interfaces and tap into the competition for attention between thoughts that race through our mind.”

To do that, the team arranged for a situation in which two concepts competed for dominance in the mind of the patient. “We had patients sit in front of a blank screen and asked them to think of one of the target images,” Cerf explains. As they thought of the image, and the related neuron fired, “we made the image appear on the screen,” he says. That image is the “target.” Then one of the other three images is introduced, to serve as the “distractor.”

“The patient starts with a 50/50 image, a hybrid, representing the ‘marriage’ of the two images,” Cerf says, and then has to make the target image fade in—just using his or her mind—and the distractor fade out. During the tests, the patients came up with their own personal strategies for making the right images appear; some simply thought of the picture, while others repeated the name of the image out loud or focused their gaze on a particular aspect of the image. Regardless of their tactics, the subjects quickly got the hang of the task, and they were successful in around 70 percent of trials.

“The patients clearly found this task to be incredibly fun as they started to feel that they control things in the environment purely with their thought,” says Cerf. “They were highly enthusiastic to try new things and see the boundaries of ‘thoughts’ that still allow them to activate things in the environment.”

Notably, even in cases where the patients were on the verge of failure—with, say, the distractor image representing 90 percent of the composite picture, so that it was essentially all the patients saw—”they were able to pull it back,” Cerf says. Imagine, for example, that the target image is Bill Clinton and the distractor George Bush. When the patient is “failing” the task, the George Bush image will dominate. “The patient will see George Bush, but they’re supposed to be thinking about Bill Clinton. So they shut off Bush—somehow figuring out how to control the flow of that information in their brain—and make other information appear. The imagery in their brain,” he says, “is stronger than the hybrid image on the screen.”

According to Koch, what is most exciting “is the discovery that the part of the brain that stores the instruction ‘think of Clinton’ reaches into the medial temporal lobe and excites the set of neurons responding to Clinton, simultaneously suppressing the population of neurons representing Bush, while leaving the vast majority of cells representing other concepts or familiar person untouched.”

The work in the paper, “On-line voluntary control of human temporal lobe neurons,” is part of a decade-long collaboration between the Fried and Koch groups, funded by the National Institute of Neurological Disorders and Stroke, the National Institute of Mental Health, the G. Harold & Leila Y. Mathers Charitable Foundation, and Korea’s World Class University program.

Source: California Institute of Technology (Caltech)

Research suggests humans can learn to consciously control individual neurons in the brain. Image credit: Moran Cerf and Maria Moon/Caltech

Brain-Machine Interface

March 4, 2011 3 comments

Formerly only in the domain of fantasy, brain-controlled devices now exist. These complex robotic tools are made possible by past studies of nerve cell communication.

This has implications for the approximately 5.6 million Americans, about 1.9 percent of the population, who are paralyzed. While some treatments focus on ways to repair the damage, other approaches aim to restore some independence by helping patients control a device, such as a robotic arm or computer cursor.

The Discovery

Finding out how the brain controls movement

Every handshake or footstep is the result of the brain exchanging information with an arm or leg. But what if that link is severed? Research shows function may be restored with mechanical limbs. Such brain-machine connections are now possible because of experiments that examined nerve cell communication.

Strength in Numbers of Neurons

In the 1920s, researchers investigating electrical activity in the brain noticed the signals they recorded varied with a person’s behavior. Nerve cells in the brain called neurons communicate with each other via chemicals and bursts or “spikes” of electricity. Using instruments attached to the outside of the scalp, the researchers found evidence that these signals are related to behavior.

(Left: Image Description (above): Microwire arrays such as the one shown have made brain-controlled devices possible. The arrays are implanted into the brain’s motor region to record the electrical signals of individual neurons simultaneously. Credit: Miguel Nicolelis, MD, PhD; Duke University.)

Years later, scientists recorded signals from individual nerve cells by implanting tiny rigid wires in the brains of macaque monkeys. They found each cell in the motor cortex, the brain’s movement control center, responded differently when the monkey moved its arm in certain directions. This led researchers to believe single neurons controlled behavior.

However, subsequent research showed the collective effort of nerve cells working together directs behavior. In the early 1990s, arrays of implanted electrodes with flexible wires allowed researchers to record almost 50 neurons at once in a conscious animal. As the animal moved, each cell’s electrical signal changed and was logged. These studies suggested brain cells compute in clusters, not in isolation. This was a surprising finding.

Although basic tools had been developed to tap into the brain’s electrical signals, the full potential of that discovery was still unknown. Researchers needed a way to apply those extracted signals to restore motor function; they needed an interface between neurons and artificial devices.

New Application

Animals control machines with their brains

Researchers worked to create a system that could continuously tap into diverse populations of neurons, convert their signals into commands a robot could understand, and then immediately transmit those commands to the machine. Basic science research in animals helped identify three essential components to a brain-machine interface: simply thinking of an action activates motor-control neurons; the signals from hundreds but not thousands of motor neurons are needed to imitate natural movement; and sensory feedback is necessary for proper control of a brain-directed prosthetic.

Movement Without Flexing a Muscle

Remarkably, researchers found that thinking about a motion activates neurons in the same pattern that actually making the movement does. In one early experiment, a rat was trained to expect a reward when it pressed a lever. Researchers then disconnected the lever from the reward and equipped the rat with an electrode array that collected and processed data from about 50 neurons in the motor cortex involved in lever pressing. Even then, the rat still attained the reward, despite never physically touching the lever.

(Left: A simplified schematic shows how signals from nerve cells in the brain’s motor cortex can control a prosthetic device. Electrical communications between neurons are recorded, processed through a machine interface, and used to control a motorized arm. Credit: Reprinted by permission from Macmillan Publishers Ltd: Nature Reviews Neuroscience 4(5):417–422, © 2003.)

Scientists then attempted to design a robotic arm that mimicked the motions of a monkey’s arm. The researchers found that to accurately reproduce motion, they had to record many, but not all neurons involved in arm movement. They sampled 50 to 100 neurons throughout the arm sensation and movement control areas in a monkey’s brain at any given time. Signals from those neurons were processed and rerouted to control a robotic arm. When the monkey

reached for a piece of fruit, so did the machine. This finding suggests that people who are injured or ill can still make use of brain-directed prosthetics even with nerve cell loss.

(Left: Basic science research in animals has led to important advances in technologies like brain-controlled machines that could help individuals with central nervous system disorders. A rhesus monkey feeds itself by operating a prosthetic arm through a brain-machine interface. Credit: Motorlab, University of Pittsburgh School of Medicine.)

Also during these landmark experiments, researchers found when they displayed a visual indicator of a neuron’s activity, a monkey could learn to move its limbs to control the cell firing rate. This discovery suggested that, with training and proper sensory feedback, people could learn to control brain signals to operate complex robotic devices. In this way, machines could act in lieu, not in imitation, of a hand or an arm.

Health Implications

New solutions for paralyzed people

Thanks to the success of animal studies, pieces are in place to apply brain-machine systems to the most complex organ: the human brain. Human tests of brain-controlled prosthetics have already begun. In carefully monitored clinical trials, paralyzed people have had sensors surgically implanted in their brains to allow them to move a glass of water or use a computer.

Building a Better Machine

Privately held companies are teaming up with government agencies and academic institutions to develop viable brain-operated robotic devices and computers. In one early trial, a participant controlled a cursor on a computer screen, an activity he had been unable to do since an accident severely damaged his spinal cord. One paralyzed volunteer with an implant recently demonstrated her ability to move a robotic arm with her thoughts. The woman directed the arm to pick up a glass and set it back down.

Similar systems also have given new voices to people unable to speak. The most well-known user of communication technology is the physicist Stephen Hawking, who has a slowly progressing form of amyotrophic lateral sclerosis. Although Hawking uses two fingers to construct sentences on a speech-capable computer, researchers aim to develop such communication systems to act on thought only.

(Left: Basic science research in animals has led to important advances in technologies like brain-controlled machines that could help individuals with central nervous system disorders. A rhesus monkey feeds itself by operating a prosthetic arm through a brain-machine interface. Credit: Motorlab, University of Pittsburgh School of Medicine.)

So far individuals have largely received implants that physically plug into machines. Although implants are most effective at reading brain signals, non-invasive interfaces for humans are in development to avoid risk of infection and tissue damage. Even small advances are huge improvements for people who are “locked in” to their bodies due to paralysis.

New Scale of Science

Brain-machine research has given scientists new insight into how the brain works. Before such research, scientists were uncertain how strokes or injuries alter the brain’s ability to control the body. Now, thanks to brain-machine connections that track neuron activity in exquisite detail, scientists know that if a lost connection is restored, the brain may still be able to relay motor commands. This finding has profound implications for both machine-assisted recovery and spinal cord repair.


Source: Society for Neuroscience