Archive for the ‘traumatic brain injury’ Category

New research published in the Canadian Medical Association Journal shows that even mild concussions sustained in ordinary community settings might be more detrimental than anyone anticipated; the long-term risk of suicide increases threefold in adults if they have experienced even one concussion. That risk increases by a third if the concussion is sustained on a weekend instead of a weekday—suggesting recreational concussions are riskier long-term than those sustained on the job.

“The typical patient I see is a middle-aged adult, not an elite athlete,” says Donald Redelmeier, a senior scientist at the University of Toronto and one of the study’s lead authors. “And the usual circumstances for acquiring a concussion are not while playing football; it is when driving in traffic and getting into a crash, when missing a step and falling down a staircase, when getting overly ambitious about home repairs—the everyday activities of life.”

Redelmeier and his team wanted to examine the risks of the concussions acquired under those circumstances. They identified nearly a quarter of a million adults in Ontario who were diagnosed with a mild concussion over a timespan of 20 years—severe cases that resulted in hospital admission were excluded from the study—and tracked them for subsequent mortality due to suicide. It turned out that more than 660 suicides occurred among these patients, equivalent to 31 deaths per 100,000 patients annually—three times the population norm. On average, suicide occurred almost six years after the concussion. This risk was found to be independent of demographics or previous psychiatric conditions, and it increased with additional concussions.

For weekend concussions, the later suicide risk increased to four times the norm. Redelmeier and his fellow researchers had wondered whether the risk would differ between occupational and recreational concussions. They did not have information about how the concussions happened, so they used day of the week as a proxy. Although they do not know why weekend risk is indeed higher, they suspect it may be because on weekends medical staff may not be as available or accessible or people may not seek immediate care.

Although the underlying causes of the connection between concussion and suicide are not yet known, Redelmeier says that there were at least three potential explanations. A concussion may be a marker but not necessarily a mechanism of subsequent troubles—or, in other words, people who sustain concussions may already have baseline life imbalances that increase their risks for depression and suicide. “But we also looked at the subgroup of patients who had no past psychiatric history, no past problems, and we still found a significant increase in risk. So I don’t think that’s the entire story,” he notes. One of the more likely explanations, he says, is that concussion causes brain injury such as inflammation (as has been found in some studies) from which the patient may never fully recover. Indeed, a study conducted in 2014 found that sustaining a head injury leads to a greater risk of mental illness later in life. The other possibility is that some patients may not give themselves enough time to get better before returning to an ordinary schedule, leading to strain, frustration and disappointment—which, in turn, may result in depression and ultimately even suicide.

Lea Alhilali, a physician and researcher at the Barrow Neurological Institute who did not participate in this study, uses diffusion tensor imaging (an MRI technique) to measure the integrity of white matter in the brain. Her team has found similarities between white matter degeneration patterns in patients with concussion-related depression and noninjured patients with major depressive disorder—particularly in the nucleus accumbens, or the “reward center” of the brain. “It can be difficult to tease out what’s related to an injury and what’s related to the circumstances surrounding the trauma,” Alhilali says. “There could be PTSD, loss of job, orthopedic injuries that can all influence depression. But I do believe there’s probably an organic brain injury.”

Alhilali points to recent studies on chronic traumatic encephalopathy (CTE), a progressive degenerative brain disease associated with repeated head traumas. Often linked to dementia, depression, loss of impulse control and suicide, CTE was recently diagnosed in 87 of 91 deceased NFL players. Why, then, she says, should we not suspect that concussion causes other brain damage as well?

This new study may only represent the tip of the iceberg. “We’re only looking at the most extreme outcomes, at taking your own life,” Redelmeier says. “But for every person who dies from suicide, there are many others who attempt suicide, and hundreds more who think about it and thousands more who suffer from depression.”

More research needs to be done; this study was unable to take into account the exact circumstances under which the concussions were sustained. Redelmeier’s research examined only the records of adults who sought medical attention, it did not include more severe head injuries that required hospitalization or extensive emergency care. To that extent, his findings may have underestimated the magnitude of the absolute risks at hand.

Yet many people are not aware of these risks.

Redelmeier is adamant that people should take concussions seriously. “We need to do more research about prevention and recovery,” he says. “But let me at least articulate three things to do: One, give yourself permission to get some rest. Two, when you start to feel better, don’t try to come back with a vengeance. And three, even after you’re feeling better, after you’ve rested properly, don’t forget about it entirely. If you had an allergic reaction to penicillin 15 years ago, you’d want to mention that to your doctor and have it as a permanent part of your medical record. So, too, if you’ve had a concussion 15 years ago.”

http://www.scientificamerican.com/article/a-single-concussion-may-triple-the-long-term-risk-of-suicide1/


Over the past 15 years, more than 330,000 US soldiers have suffered a traumatic brain injury. Many were evacuated by air for further treatment. A new study has found evidence that such air evacuations may pose a significant added risk, potentially causing more damage to already injured brains.

Over the past 15 years, more than 330,000 U.S. soldiers have suffered a traumatic brain injury (TBI). It is one of the leading causes of death and disability connected to the country’s recent conflicts in Afghanistan and Iraq. Many of these patients were evacuated by air from these countries to Europe and the U.S. for further treatment. In general, these patients were flown quickly to hospitals outside the battle zone, where more extensive treatment was available.

But now a new study by researchers at the University of Maryland School of Medicine has found evidence that such air evacuations may pose a significant added risk, potentially causing more damage to already injured brains. The study is the first to suggest that air evacuation may be hazardous for TBI patients. The study was published in the Journal of Neurotrauma.

“This research shows that exposure to reduced barometric pressure, as occurs on military planes used for evacuation, substantially worsens neurological function and increases brain cell loss after experimental TBI — even when oxygen levels are kept in the normal range. It suggests that we need to carefully re-evaluate the cost-benefit of air transport in the first days after injury,” said lead researcher Alan Faden, MD, the David S. Brown Professor in Trauma in the Departments of Anesthesiology, Anatomy & Neurobiology, Neurology, and Neurosurgery, and director, Shock, Trauma and Anesthesiology Research Center (STAR) as well as the National Study Center for Trauma and Emergency Medical Services.

About a quarter of all injured soldiers evacuated from Afghanistan and Iraq have suffered head injuries.

Faden and his colleagues tested rats that were subjected to TBI, using a model that simulates key aspects of human brain injury. Animals were exposed to six hours of lowered air pressure, known as hypobaria, at levels that simulated conditions during transport; control animals were exposed to normal pressure. All the animals received extra oxygen to restore normal oxygen concentrations in the blood. In another study, animals received oxygen, either as in the first study or at much higher 100 percent concentration, which is often used during military air evacuations. On its own, low air pressure worsened long-term cognitive function and increased chronic brain inflammation and brain tissue loss. Pure oxygen further worsened outcomes.

Faden and his colleagues believe the findings raise concerns about the increased use of relatively early air evacuation, and suggest that this potential risk should be weighed against the benefits of improved care after evacuation. It may be necessary, he says, to change the current policy for TBI patients and delaying air evacuation in many cases.

In an accompanying editorial, Patrick Kochanek, MD, a leading expert on TBI and trauma care at the University of Pittsburgh, called the findings “highly novel and eye-opening,” and said that they could have “impactful clinical relevance for the field of traumatic brain injury in both military and civilian applications.”

Faden and colleagues believe that one of the mechanisms by which hypobaria worsens TBI is by increasing persistent brain inflammation after injury. They are currently examining how this process occurs and have tested treatments that can reduce the risks of air evacuation. Early results are promising. Scientists suspect that breathing pure oxygen could worsen TBI by increasing production of dangerous free radicals in the brain. After brain injury, these free radicals flood the site of injury, and pure oxygen may further boost these levels. Several recent studies from trauma centers, including from the R Adams Cowley Shock Trauma Center at the University of Maryland Medical Center, have found evidence that using 100 percent oxygen in trauma patients may be counterproductive.

Journal Reference:

Jacob W Skovira, Shruti V Kabadi, Junfang Wu, Zaorui Zhao, Joseph DuBose, Robert E Rosenthal, Gary Fiskum, Alan I Faden. Simulated Aeromedical Evacuation Exacerbates Experimental Brain Injury. Journal of Neurotrauma, 2015; DOI: 10.1089/neu.2015.4189

http://www.sciencedaily.com/releases/2015/11/151130110013.htm

brain

The many documented cases of strange delusions and neurological syndromes can offer a window into how bizarre the brain can be.

It may seem that hallucinations are random images that appear to some individuals, or that delusions are thoughts that arise without purpose. However, in some cases, a specific brain pathway may create a particular image or delusion, and different people may experience the same hallucination.

In recent decades, with advances in brain science, researchers have started to unravel the causes of some of these conditions, while others have remained a mystery.

Here is a look at seven odd hallucinations, which show that anything is possible when the brain takes a break from reality.

1. Alice-in-Wonderland syndrome
This neurological syndrome is characterized by bizarre, distorted perceptions of time and space, similar to what Alice experienced in Lewis Carroll’s “Alice’s Adventures in Wonderland.”

Patients with Alice-in-Wonderland syndrome describe seeing objects or parts of their bodies as smaller or bigger than their actual sizes, or in an altered shape. These individuals may also perceive time differently.

The rare syndrome seems to be caused by some viral infections, epilepsy, migraine headaches and brain tumors. Studies have also suggested that abnormal activity in parts of the visual cortex that handle information about the shape and size of objects might cause the hallucinations.

It’s also been suggested that Carroll himself experienced the condition during migraine headaches and used them as inspiration for writing the tale of Alice’s strange dream.

English psychiatrist John Todd first described the condition in an article published in the Canadian Medical Association Journal in 1955, and that’s why the condition is also called Todd’s syndrome. However, an earlier reference to the condition appears in a 1952 article by American neurologist Caro Lippman. The doctor describes a patient who reported feeling short and wide as she walked, and referenced “Alice’s Adventures in Wonderland” to explain her body image illusions.

2. Walking Corpse Syndrome
This delusion, also called Cotard’s Syndrome, is a rare mental illness in which patients believe they are dead, are dying or have lost their internal organs.

French neurologist Jules Cotard first described the condition in 1880, finding it in a woman who had depression and also symptoms of psychosis. The patient believed she didn’t have a brain or intestines, and didn’t need to eat. She died of starvation.

Other cases of Cotard’s syndrome have been reported in people with a range of psychiatric and neurological problems, including schizophrenia, traumatic brain injury and multiple sclerosis.

In a recent case report of Cotard’s syndrome, researchers described a previously healthy 73-year-old woman who went to the emergency room insisting that she was “going to die and going to hell.” Eventually, doctors found the patient had bleeding in her brain due to a stroke. After she received treatment in the hospital, her delusion resolved within a week, according to the report published in January 2014 in the journal of Neuropsychiatry.

3. Charles Bonnet syndrome
People who have lost their sight may develop Charles Bonnet syndrome, which involves having vivid, complex visual hallucinations of things that aren’t really there.

People with this syndrome usually hallucinate people’s faces, cartoons, colored patterns and objects. It is thought the condition occurs because the brain’s visual system is no longer receiving visual information from the eye or part of the retina, and begins making up its own images.

Charles Bonnet syndrome occurs in between 10 and 40% of older adults who have significant vision loss, according to studies.

4. Clinical lycanthropy
In this extremely rare psychiatric condition, patients believe they are turning into wolves or other animals. They may perceive their own bodies differently, and insist they are growing the fur, sharp teeth and claws of a wolf.

Cases have also been reported of people with delusional beliefs about turning into dogs, pigs, frogs and snakes.

The condition usually occurs in combination with another disorder, such as schizophrenia, bipolar disorder or severe depression, according to a review study published in the March issue of the journal History of Psychiatry in 2014.

5. Capgras delusion
Patients with Capgras delusion believe that an imposter has replaced a person they feel close to, such as a friend or spouse. The delusion has been reported in patients with schizophrenia, Alzheimer’s disease, advanced Parkinson’s disease, dementia and brain lesions.

One brain imaging study suggested the condition may involve reduced neural activity in the brain system that processes information about faces and emotional responses.

6. Othello syndrome
Named after Shakespeare’s character, Othello syndrome involves a paranoid belief that the sufferer’s partner is cheating. People with this condition experience strong obsessive thoughts and may show aggression and violence.

In one recent case report, doctors described a 46-year-old married man in the African country Burkina Faso who had a stroke, which left him unable to communicate and paralyzed in half of his body. The patient gradually recovered from his paralysis and speaking problems, but developed a persistent delusional jealousy and aggression toward his wife, accusing her of cheating with an unidentified man.

7. Ekbom’s syndrome
Patients with Ekbom’s syndrome, also known as delusional parasitosis or delusional infestations, strongly believe they are infested with parasites that are crawling under their skin. Patients report sensations of itching and being bitten, and sometimes, in an effort to get rid of the pathogens, they may hurt themselves, which can result in wounds and actual infections.

It’s unknown what causes these delusions, but studies have linked the condition with structural changes in the brain, and some patients have improved when treated with antipsychotic medications.

http://www.livescience.com/46477-oddest-hallucinations.html

When Anthony Gonzales received a hard tackle while playing rugby in 2011, he didn’t know if he had a concussion — despite showing possible symptoms. His story is a common one among young athletes — a dangerous prospect if you consider the potential consequences of an undetected head injury.

The Centers for Disease Control and Prevention report that each year, American emergency departments treat an estimated 173,285 sports- and recreation-related traumatic brain injuries (TBIs), including concussions, among athletes aged 19 and younger. Though symptoms can be subtle and difficult to detect, these head injuries can lead to lifelong cognitive problems that affect memory, behavior, and emotions. If repeated within a short period of time, head trauma can cause more serious brain problems or even death.

To help reduce the number of athletes who return to play too early and risk worsening an existing injury, Gonzales and fellow Arizona State University alum Bob Merriman developed the FITGuard, a mouthguard that indicates when a blow to the head is serious enough to warrant further attention.

The FITGuard has a green LED strip on the front that turns blue when it detects a medium force impact and red when there’s an above-50 percent chance the athlete has suffered a concussion. The athlete can then use an app to download a data log showing why the guard is displaying a given color. The data will also be uploaded to a central database to help the FIT team improve the device.

“[The FITGuard] will allow parents, coaches and leagues to follow their normal concussion protocol while having some quantitative data to support their conclusion,” Gonzales said in the video above. “We want to provide them with the tools to make informed decisions about the safety of athletes and reduce the traumatic effects of brain injury.”

The company has so far won several thousand dollars in grant funding, begun software development and produced several prototypes. If it works as planned, the FITGuard could be a big step forward in the proper treatment and diagnosis of head injuries, protecting athletes and helping relieve anxious parents and coaches.

While the issue of concussion prevention has received increased attention in recent years, including a $30 million donation by the NFL to the National Institutes of Health for medical research, sports-related brain injuries remain common, with the majority of cases involving young athletes. President Obama even hosted a summit on youth sports concussions this week at the White House to call attention to the issue.

The FITGuard is one of many recent strategies to limit the effects of head trauma, including new and improved helmets and stricter enforcement of concussion protocol, which generally consists of a medical examination for any changes in a player’s behavior, thinking, or physical functioning.

Though they haven’t brought their product to market yet, Gonzales has high hopes for his product: “Our device, made right here in the good old U.S.A., is the next step in sports evolution.”

http://www.huffingtonpost.com/2014/06/03/concussion-mouth-guard-fitguard_n_5399966.html?ncid=fcbklnkushpmg00000063

In 2002, two men savagely attacked Jason Padgett outside a karaoke bar, leaving him with a severe concussion and post-traumatic stress disorder. But the incident also turned Padgett into a mathematical genius who sees the world through the lens of geometry.

Padgett, a furniture salesman from Tacoma, Wash., who had very little interest in academics, developed the ability to visualize complex mathematical objects and physics concepts intuitively. The injury, while devastating, seems to have unlocked part of his brain that makes everything in his world appear to have a mathematical structure.

“I see shapes and angles everywhere in real life” — from the geometry of a rainbow, to the fractals in water spiraling down a drain, Padgett told Live Science. “It’s just really beautiful.”

Padgett, who just published a memoir with Maureen Seaberg called “Struck by Genius” (Houghton Mifflin Harcourt, 2014), is one of a rare set of individuals with acquired savant syndrome, in which a normal person develops prodigious abilities after a severe injury or disease. Other people have developed remarkable musical or artistic abilities, but few people have acquired mathematical faculties like Padgett’s.

Now, researchers have figured out which parts of the man’s brain were rejiggered to allow for such savant skills, and the findings suggest such skills may lie dormant in all human brains.

Before the injury, Padgett was a self-described jock and partyer. He hadn’t progressed beyond than pre-algebra in his math studies. “I cheated on everything, and I never cracked a book,” he said.

But all that would change the night of his attack. Padgett recalls being knocked out for a split second and seeing a bright flash of light. Two guys started beating him, kicking him in the head as he tried to fight back. Later that night, doctors diagnosed Padgett with a severe concussion and a bleeding kidney, and sent him home with pain medications, he said.

Soon after the attack, Padgett suffered from PTSD and debilitating social anxiety. But at the same time, he noticed that everything looked different. He describes his vision as “discrete picture frames with a line connecting them, but still at real speed.” If you think of vision as the brain taking pictures all the time and smoothing them into a video, it’s as though Padgett sees the frames without the smoothing. In addition, “everything has a pixilated look,” he said.

With Padgett’s new vision came an astounding mathematical drawing ability. He started sketching circles made of overlapping triangles, which helped him understand the concept of pi, the ratio of a circle’s circumference to its diameter. There’s no such thing as a perfect circle, he said, which he knows because he can always see the edges of a polygon that approximates the circle.

Padgett dislikes the concept of infinity, because he sees every shape as a finite construction of smaller and smaller units that approach what physicists refer to as the Planck length, thought to be the shortest measurable length.

After his injury, Padgett was drawing complex geometric shapes, but he didn’t have the formal training to understand the equations they represented. One day, a physicist spotted him making these drawings in a mall, and urged him to pursue mathematical training. Now Padgett is a sophomore in college and an aspiring number theorist.

Padgett’s remarkable abilities garnered the interest of neuroscientists who wanted to understand how he developed them.

Berit Brogaard, a philosophy professor now at the University of Miami, in Coral Gables, Fla., and her colleagues scanned Padgett’s brain with functional magnetic resonance imaging (fMRI) to understand how he acquired his savant skills and the synesthesia that allows him to perceive mathematical formulas as geometric figures. (Synesthesia is a phenomenon in which one sense bleeds into another.)

“Acquired savant syndrome is very rare,” Brogaard said, adding that only 15 to 25 cases have ever been described in medical studies.

Functional magnetic resonance imaging measures changes in blood flow and oxygen use throughout the brain. During scans of Padgett, the researchers showed the man real and nonsense mathematical formulas meant to conjure images in his mind.

The resulting scans showed significant activity in the left hemisphere of Padgett’s brain, where mathematical skills have been shown to reside. His brain lit up most strongly in the left parietal cortex, an area behind the crown of the head that is known to integrate information from different senses. There was also some activation in parts of his temporal lobe (involved in visual memory, sensory processing and emotion) and frontal lobe (involved in executive function, planning and attention).

But the fMRI only showed what areas were active in Padgett’s brain. In order to show these particular areas were causing the man’s synesthesia, Brogaard’s team used transcranial magnetic stimulation (TMS), which involves zapping the brain with a magnetic pulse that activates or inhibits a specific region. When they zapped the parts of Padgett’s parietal cortex that had shown the greatest activity in the fMRI scans, it made his synesthesia fade or disappear, according to a study published in August 2013 in the journal Neurocase.

Brogaard showed, in another study, that when neurons die, they release brain-signaling chemicals that can increase brain activity in surrounding areas. The increased activity usually fades over time, but sometimes it results in structural changes that can cause brain-activity modifications to persist, Brogaard told Live Science.

Scientists don’t know whether the changes in Padgett’s brain are permanent, but if he had structural changes, it’s more likely his abilities are here to stay, Brogaard said.

So do abilities like Padgett’s lie dormant in everyone, waiting to be uncovered? Or was there something unique about Padgett’s brain to begin with?

Most likely, there is something dormant in everyone that Padgett tapped into, Brogaard said. “It would be quite a coincidence if he were to have that particular special brain and then have an injury,” she said. “And he’s not the only [acquired savant].”

In addition to head injuries, mental disease has also been known to reveal latent abilities. And Brogaard and others have done studies that suggest zapping the brains of normal people using TMS can temporarily bring out unusual mathematical and artistic skills.

Yet Padgett wouldn’t change his new abilities if he could. “It’s so good, I can’t even describe it,” he said.

It’s always possible that having savant skills may come with trade-offs. In Padgett’s case, he developed fairly severe post-traumatic stress disorder and obsessive-compulsive disorder, and he still finds it difficult to appear in public.

http://news.discovery.com/human/life/brain-injury-turns-man-into-math-genius-1405061.htm

 

 

Stanford researchers have designed the fastest, most accurate mathematical algorithm yet for brain-implantable prosthetic systems that can help disabled people maneuver computer cursors with their thoughts. The algorithm’s speed, accuracy and natural movement approach those of a real arm.

 

 

On each side of the screen, a monkey moves a cursor with its thoughts, using the cursor to make contact with the colored ball. On the left, the monkey’s thoughts are decoded with the use of a mathematical algorithm known as Velocity. On the right, the monkey’s thoughts are decoded with a new algorithm known as ReFITT, with better results. The ReFIT system helps the monkey to click on 21 targets in 21 seconds, as opposed to just 10 clicks with the older system.

 

 

When a paralyzed person imagines moving a limb, cells in the part of the brain that controls movement activate, as if trying to make the immobile limb work again.

Despite a neurological injury or disease that has severed the pathway between brain and muscle, the region where the signals originate remains intact and functional.

In recent years, neuroscientists and neuroengineers working in prosthetics have begun to develop brain-implantable sensors that can measure signals from individual neurons.

After those signals have been decoded through a mathematical algorithm, they can be used to control the movement of a cursor on a computer screen – in essence, the cursor is controlled by thoughts.

The work is part of a field known as neural prosthetics.

A team of Stanford researchers have now developed a new algorithm, known as ReFIT, that vastly improves the speed and accuracy of neural prosthetics that control computer cursors. The results were published Nov. 18 in the journal Nature Neuroscience in a paper by Krishna Shenoy, a professor of electrical engineering, bioengineering and neurobiology at Stanford, and a team led by research associate Dr. Vikash Gilja and bioengineering doctoral candidate Paul Nuyujukian.

In side-by-side demonstrations with rhesus monkeys, cursors controlled by the new algorithm doubled the performance of existing systems and approached performance of the monkey’s actual arm in controlling the cursor. Better yet, more than four years after implantation, the new system is still going strong, while previous systems have seen a steady decline in performance over time.

“These findings could lead to greatly improved prosthetic system performance and robustness in paralyzed people, which we are actively pursuing as part of the FDA Phase-I BrainGate2 clinical trial here at Stanford,” said Shenoy.

The system relies on a sensor implanted into the brain, which records “action potentials” in neural activity from an array of electrode sensors and sends data to a computer. The frequency with which action potentials are generated provides the computer important information about the direction and speed of the user’s intended movement.

The ReFIT algorithm that decodes these signals represents a departure from earlier models. In most neural prosthetics research, scientists have recorded brain activity while the subject moves or imagines moving an arm, analyzing the data after the fact. “Quite a bit of the work in neural prosthetics has focused on this sort of offline reconstruction,” said Gilja, the first author of the paper.

The Stanford team wanted to understand how the system worked “online,” under closed-loop control conditions in which the computer analyzes and implements visual feedback gathered in real time as the monkey neurally controls the cursor toward an onscreen target.

The system is able to make adjustments on the fly when guiding the cursor to a target, just as a hand and eye would work in tandem to move a mouse-cursor onto an icon on a computer desktop.

If the cursor were straying too far to the left, for instance, the user likely adjusts the imagined movements to redirect the cursor to the right. The team designed the system to learn from the user’s corrective movements, allowing the cursor to move more precisely than it could in earlier prosthetics.

To test the new system, the team gave monkeys the task of mentally directing a cursor to a target – an onscreen dot – and holding the cursor there for half a second. ReFIT performed vastly better than previous technology in terms of both speed and accuracy.

The path of the cursor from the starting point to the target was straighter and it reached the target twice as quickly as earlier systems, achieving 75 to 85 percent of the speed of the monkey’s arm.

“This paper reports very exciting innovations in closed-loop decoding for brain-machine interfaces. These innovations should lead to a significant boost in the control of neuroprosthetic devices and increase the clinical viability of this technology,” said Jose Carmena, an associate professor of electrical engineering and neuroscience at the University of California-Berkeley.

Critical to ReFIT’s time-to-target improvement was its superior ability to stop the cursor. While the old model’s cursor reached the target almost as fast as ReFIT, it often overshot the destination, requiring additional time and multiple passes to hold the target.

The key to this efficiency was in the step-by-step calculation that transforms electrical signals from the brain into movements of the cursor onscreen. The team had a unique way of “training” the algorithm about movement. When the monkey used his arm to move the cursor, the computer used signals from the implant to match the arm movements with neural activity.

Next, the monkey simply thought about moving the cursor, and the computer translated that neural activity into onscreen movement of the cursor. The team then used the monkey’s brain activity to refine their algorithm, increasing its accuracy.

The team introduced a second innovation in the way ReFIT encodes information about the position and velocity of the cursor. Gilja said that previous algorithms could interpret neural signals about either the cursor’s position or its velocity, but not both at once. ReFIT can do both, resulting in faster, cleaner movements of the cursor.

Early research in neural prosthetics had the goal of understanding the brain and its systems more thoroughly, Gilja said, but he and his team wanted to build on this approach by taking a more pragmatic engineering perspective. “The core engineering goal is to achieve highest possible performance and robustness for a potential clinical device,” he said.

To create such a responsive system, the team decided to abandon one of the traditional methods in neural prosthetics.

Much of the existing research in this field has focused on differentiating among individual neurons in the brain. Importantly, such a detailed approach has allowed neuroscientists to create a detailed understanding of the individual neurons that control arm movement.

But the individual neuron approach has its drawbacks, Gilja said. “From an engineering perspective, the process of isolating single neurons is difficult, due to minute physical movements between the electrode and nearby neurons, making it error prone,” he said. ReFIT focuses on small groups of neurons instead of single neurons.

By abandoning the single-neuron approach, the team also reaped a surprising benefit: performance longevity. Neural implant systems that are fine-tuned to specific neurons degrade over time. It is a common belief in the field that after six months to a year they can no longer accurately interpret the brain’s intended movement. Gilja said the Stanford system is working very well more than four years later.

“Despite great progress in brain-computer interfaces to control the movement of devices such as prosthetic limbs, we’ve been left so far with halting, jerky, Etch-a-Sketch-like movements. Dr. Shenoy’s study is a big step toward clinically useful brain-machine technology that has faster, smoother, more natural movements,” said James Gnadt, a program director in Systems and Cognitive Neuroscience at the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health.

For the time being, the team has been focused on improving cursor movement rather than the creation of robotic limbs, but that is not out of the question, Gilja said. Near term, precise, accurate control of a cursor is a simplified task with enormous value for people with paralysis.

“We think we have a good chance of giving them something very useful,” he said. The team is now translating these innovations to people with paralysis as part of a clinical trial.

This research was funded by the Christopher and Dana Reeve Paralysis Foundation, the National Science Foundation, National Defense Science and Engineering Graduate Fellowships, Stanford Graduate Fellowships, Defense Advanced Research Projects Agency (“Revolutionizing Prosthetics” and “REPAIR”) and the National Institutes of Health (NINDS-CRCNS and Director’s Pioneer Award).

Other contributing researchers include Cynthia Chestek, John Cunningham, Byron Yu, Joline Fan, Mark Churchland, Matthew Kaufman, Jonathan Kao and Stephen Ryu.

http://news.stanford.edu/news/2012/november/thought-control-cursor-111812.html

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community