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New surgery may help amputees control muscles and sense their 'phantom limb'
Reconnecting muscle pairs allows for better sensory feedback from the limb.
This restored sense of proprioception should translate to better control of prosthetic limbs, as well as a reduction of limb pain, the researchers say.
In most amputations, muscle pairs that control the affected joints, such as elbows or ankles, are severed. However, the MIT team has found that reconnecting these muscle pairs, allowing them to retain their normal push-pull relationship, offers people much better sensory feedback.
"Both our study and previous studies show that the better patients can dynamically move their muscles, the more control they're going to have. The better a person can actuate muscles that move their phantom ankle, for example, the better they're actually able to use their prostheses," says Shriya Srinivasan, an MIT postdoc and lead author of the study.
In a study that will appear this week in the Proceedings of the National Academy of Sciences, 15 patients who received this new type of surgery, known as agonist-antagonist myoneural interface (AMI), could control their muscles more precisely than patients with traditional amputations. The AMI patients also reported feeling more freedom of movement and less pain in their affected limb.
"Through surgical and regenerative techniques that restore natural agonist-antagonist muscle movements, our study shows that persons with an AMI amputation experience a greater phantom joint range of motion, a reduced level of pain, and an increased fidelity of prosthetic limb controllability," says Hugh Herr, a professor of media arts and sciences, head of the Biomechatronics group in the Media Lab, and the senior author of the paper.
Other authors of the paper include Samantha Gutierrez-Arango and Erica Israel, senior research support associates at the Media Lab; Ashley Chia-En Teng, an MIT undergraduate; Hyungeun Song, a graduate student in the Harvard-MIT Program in Health Sciences and Technology; Zachary Bailey, a former visiting researcher at the Media Lab; Matthew Carty, a visiting scientist at the Media Lab; and Lisa Freed, a Media Lab research scientist.
Most muscles that control limb movement occur in pairs that alternately stretch and contract. One example of these agonist-antagonist pairs is the biceps and triceps. When you bend your elbow, the biceps muscle contracts, causing the triceps to stretch, and that stretch sends sensory information back to the brain.
During a conventional limb amputation, these muscle movements are restricted, cutting off this sensory feedback and making it much harder for amputees to feel where their prosthetic limbs are in space or to sense forces applied to those limbs.
"When one muscle contracts, the other one doesn't have its antagonist activity, so the brain gets confusing signals," says Srinivasan, a former member of the Biomechatronics group now working at MIT's Koch Institute for Integrative Cancer Research. "Even with state-of-the-art prostheses, people are constantly visually following the prosthesis to try to calibrate their brains to where the device is moving."
A few years ago, the MIT Biomechatronics group invented and scientifically developed in preclinical studies a new amputation technique that maintains the relationships between those muscle pairs. Instead of severing each muscle, they connect the two ends of the muscles so that they still dynamically communicate with each other within the residual limb. In a 2017 study of rats, they showed that when the animals contracted one muscle of the pair, the other muscle would stretch and send sensory information back to the brain.
Since these preclinical studies, about 25 people have undergone the AMI procedure at Brigham and Women's Hospital, performed by Carty, a surgeon in the Division of Plastic and Reconstructive Surgery at Brigham and Women's Hospital. In the new PNAS study, the researchers measured the precision of muscle movements in the ankle and subtalar joints of 15 patients who had AMI amputations performed below the knee. These patients had two sets of muscles reconnected during their amputation: the muscles that control the ankle, and those that control the subtalar joint, which allows the sole of the foot to tilt inward or outward. The study compared these patients to seven people who had traditional amputations below the knee.
Each patient was evaluated while lying down with their legs propped on a foam pillow, allowing their feet to extend into the air. Patients did not wear prosthetic limbs during the study. The researchers asked them to flex their ankle joints — both the intact one and the "phantom" one — by 25, 50, 75, or 100 percent of their full range of motion. Electrodes attached to each leg allowed the researchers to measure the activity of specific muscles as each movement was performed repeatedly.
The researchers compared the electrical signals coming from the muscles in the amputated limb with those from the intact limb and found that for AMI patients, they were very similar. They also found that patients with the AMI amputation were able to control the muscles of their amputated limb much more precisely than the patients with traditional amputations. Patients with traditional amputations were more likely to perform the same movement over and over in their amputated limb, regardless of how far they were asked to flex their ankle.
"The AMI patients' ability to control these muscles was a lot more intuitive than those with typical amputations, which largely had to do with the way their brain was processing how the phantom limb was moving," Srinivasan says.
In a paper that recently appeared in Science Translational Medicine, the researchers reported that brain scans of the AMI amputees showed that they were getting more sensory feedback from their residual muscles than patients with traditional amputations. In work that is now ongoing, the researchers are measuring whether this ability translates to better control of a prosthetic leg while walking.
Freedom of movement
The researchers also discovered an effect they did not anticipate: AMI patients reported much less pain and a greater sensation of freedom of movement in their amputated limbs.
"Our study wasn't specifically designed to achieve this, but it was a sentiment our subjects expressed over and over again. They had a much greater sensation of what their foot actually felt like and how it was moving in space," Srinivasan says. "It became increasingly apparent that restoring the muscles to their normal physiology had benefits not only for prosthetic control, but also for their day-to-day mental well-being."
The research team has also developed a modified version of the surgery that can be performed on people who have already had a traditional amputation. This process, which they call "regenerative AMI," involves grafting small muscle segments to serve as the agonist and antagonist muscles for an amputated joint. They are also working on developing the AMI procedure for other types of amputations, including above the knee and above and below the elbow.
"We're learning that this technique of rewiring the limb, and using spare parts to reconstruct that limb, is working, and it's applicable to various parts of the body," Herr says.
The research was funded by the MIT Media Lab Consortia; the National Institutes of Health's National Institute of Child Health and Human Development and National Center for Medical Rehabilitation Research; and the Congressionally Directed Medical Research Programs of the U.S. Department of Defense.
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Inventions with revolutionary potential made by a mysterious aerospace engineer for the U.S. Navy come to light.
- U.S. Navy holds patents for enigmatic inventions by aerospace engineer Dr. Salvatore Pais.
- Pais came up with technology that can "engineer" reality, devising an ultrafast craft, a fusion reactor, and more.
- While mostly theoretical at this point, the inventions could transform energy, space, and military sectors.
The U.S. Navy controls patents for some futuristic and outlandish technologies, some of which, dubbed "the UFO patents," came to life recently. Of particular note are inventions by the somewhat mysterious Dr. Salvatore Cezar Pais, whose tech claims to be able to "engineer reality." His slate of highly-ambitious, borderline sci-fi designs meant for use by the U.S. government range from gravitational wave generators and compact fusion reactors to next-gen hybrid aerospace-underwater crafts with revolutionary propulsion systems, and beyond.
Of course, the existence of patents does not mean these technologies have actually been created, but there is evidence that some demonstrations of operability have been successfully carried out. As investigated and reported by The War Zone, a possible reason why some of the patents may have been taken on by the Navy is that the Chinese military may also be developing similar advanced gadgets.
Among Dr. Pais's patents are designs, approved in 2018, for an aerospace-underwater craft of incredible speed and maneuverability. This cone-shaped vehicle can potentially fly just as well anywhere it may be, whether air, water or space, without leaving any heat signatures. It can achieve this by creating a quantum vacuum around itself with a very dense polarized energy field. This vacuum would allow it to repel any molecule the craft comes in contact with, no matter the medium. Manipulating "quantum field fluctuations in the local vacuum energy state," would help reduce the craft's inertia. The polarized vacuum would dramatically decrease any elemental resistance and lead to "extreme speeds," claims the paper.
Not only that, if the vacuum-creating technology can be engineered, we'd also be able to "engineer the fabric of our reality at the most fundamental level," states the patent. This would lead to major advancements in aerospace propulsion and generating power. Not to mention other reality-changing outcomes that come to mind.
Among Pais's other patents are inventions that stem from similar thinking, outlining pieces of technology necessary to make his creations come to fruition. His paper presented in 2019, titled "Room Temperature Superconducting System for Use on a Hybrid Aerospace Undersea Craft," proposes a system that can achieve superconductivity at room temperatures. This would become "a highly disruptive technology, capable of a total paradigm change in Science and Technology," conveys Pais.
High frequency gravitational wave generator.
Credit: Dr. Salvatore Pais
Another invention devised by Pais is an electromagnetic field generator that could generate "an impenetrable defensive shield to sea and land as well as space-based military and civilian assets." This shield could protect from threats like anti-ship ballistic missiles, cruise missiles that evade radar, coronal mass ejections, military satellites, and even asteroids.
Dr. Pais's ideas center around the phenomenon he dubbed "The Pais Effect". He referred to it in his writings as the "controlled motion of electrically charged matter (from solid to plasma) via accelerated spin and/or accelerated vibration under rapid (yet smooth) acceleration-deceleration-acceleration transients." In less jargon-heavy terms, Pais claims to have figured out how to spin electromagnetic fields in order to contain a fusion reaction – an accomplishment that would lead to a tremendous change in power consumption and an abundance of energy.
According to his bio in a recently published paper on a new Plasma Compression Fusion Device, which could transform energy production, Dr. Pais is a mechanical and aerospace engineer working at the Naval Air Warfare Center Aircraft Division (NAWCAD), which is headquartered in Patuxent River, Maryland. Holding a Ph.D. from Case Western Reserve University in Cleveland, Ohio, Pais was a NASA Research Fellow and worked with Northrop Grumman Aerospace Systems. His current Department of Defense work involves his "advanced knowledge of theory, analysis, and modern experimental and computational methods in aerodynamics, along with an understanding of air-vehicle and missile design, especially in the domain of hypersonic power plant and vehicle design." He also has expert knowledge of electrooptics, emerging quantum technologies (laser power generation in particular), high-energy electromagnetic field generation, and the "breakthrough field of room temperature superconductivity, as related to advanced field propulsion."
Suffice it to say, with such a list of research credentials that would make Nikola Tesla proud, Dr. Pais seems well-positioned to carry out groundbreaking work.
A craft using an inertial mass reduction device.
Credit: Salvatore Pais
The patents won't necessarily lead to these technologies ever seeing the light of day. The research has its share of detractors and nonbelievers among other scientists, who think the amount of energy required for the fields described by Pais and his ideas on electromagnetic propulsions are well beyond the scope of current tech and are nearly impossible. Yet investigators at The War Zone found comments from Navy officials that indicate the inventions are being looked at seriously enough, and some tests are taking place.
If you'd like to read through Pais's patents yourself, check them out here.
Laser Augmented Turbojet Propulsion System
Credit: Dr. Salvatore Pais
Our love-hate relationship with browser tabs drives all of us crazy. There is a solution.
A lot of ideas that people had about the internet in the 1990s have fallen by the wayside as technology and our usage patterns evolved. Long gone are things like GeoCities, BowieNet, and the belief that letting anybody post whatever they are thinking whenever they want is a fundamentally good idea with no societal repercussions.
While these ideas have been abandoned and the tools that made them possible often replaced by new and improved ones, not every outdated part of our internet experience is gone. A new study by a team at Carnegie Mellon makes the case that the use of tabs in a web browser is one of these outdated concepts that we would do well to get rid of.
How many tabs do you have open right now?
We didn't always have tabs. Introduced in the early 2000s, tabs are now included on all major web browsers, and most users have had access to them for a little over a decade. They've been pretty much the same since they came out, despite the ever changing nature of the internet. So, in this new study, researchers interviewed and surveyed 113 people on their use of — and feelings toward — the ubiquitous tabs.
Most people use tabs for the short-term storage of information, particularly if it's information that is needed again soon. Some keep tabs that they know they'll never get around to reading. Others used them as a sort of external memory bank. One participant described this action to the researchers:
"It's like a manifestation of everything that's on my mind right now. Or the things that should be on my mind right now... So right now, in this browser window, I have a web project that I'm working on. I don't have time to work on it right now, but I know I need to work on it. So it's sitting there reminding me that I need to work on it."
You suffer from tab overload
Unfortunately, trying to use tabs this way can cause a number of problems. A quarter of the interview subjects reported having caused a computer or browser to crash because they had too many tabs open. Others reported feeling flustered by having so many tabs open — a situation called "tab overload" — or feeling ashamed that they appeared disorganized by having so many tabs up at once. More than half of participants reported having problems like this at least two or three times a week.
However, people can become emotionally invested in the tabs. One participant explained, "[E]ven when I'm not using those tabs, I don't want to close them. Maybe it's because it took efforts [sic] to open those tabs and organize them in that way."
So, we have a tool that inefficiently saves web pages that we might visit again while simultaneously reducing our productivity, increasing our anxiety, and crashing our machines. And yet we feel oddly attached to them.
Either the system is crazy or we are.
Skeema: The anti-tab revolution
The researchers concluded that at least part of the problem is caused by tabs not being an ideal way of organizing the work we now do online. They propose a new model that better compartmentalizes tabs by task and subtask, reflects users' mental models, and helps manage the users' attention on what is important right now rather than what might be important later.
To that end, the team also created Skeema, an extension for Google Chrome, that treats tabs as tasks and offers a variety of ways to organize them. Users of an early version reported having fewer tabs and windows open at one time and were better able to manage the information they contained.
Tabs were an improvement over having multiple windows open at the same time, but they may have outlived their usefulness. While it might take a paradigm shift to fully replace the concept, the study suggests that taking a different approach to tabs might be worth trying.
And now, excuse me, while I close some of the 87 tabs I currently have open.
Seek pleasure and avoid pain. Why make it more complicated?
- The Epicureans were some of the world's first materialists and argued that there is neither God, nor gods, nor spirits, but only atoms and the physical world.
- They believed that life was about finding pleasure and avoiding pain and that both were achieved by minimizing our desires for things.
- The Epicurean Four Step Remedy is advice on how we can face the world, achieve happiness, and not worry as much as we do.
Self-help books are consistently on the best-seller lists across the world. We can't seem to get enough of happiness advice, wellness gurus, and life coaches. But, as the Book of Ecclesiastes says, there is nothing new under the sun. The Ancient Greeks were into the self-help business millennia before the likes of Dale Carnegie and Mark Manson.
Four schools of ancient Greek philosophy
From the 3rd century BCE until the birth of Jesus, Greek philosophy was locked into an ideological war. Four rival schools emerged, each proclaiming loudly that they — alone — had the secret to a happy and fulfilled life. These schools were: Stoicism, Cynicism, Skepticism, and Epicureanism. Each had their advocates and even had a kind of PR battle to get people to sign up to their side. They were trying to sell happiness.
Epicurus's guide to living is noticeably different from a lot of modern self-help books in just how little day-to-day advice it gives.
Many of us are familiar with Stoicism, a topic I covered recently, because it forms the foundation of cognitive behavioral therapy. Skepticism and Cynicism have become watered down or warped variations of their original forms. (I will cover these in future articles.) Today, we focus on the most underappreciated of these schools, the Epicureans. In their philosophy, we can find a surprisingly modern and easy-to-follow "Four Part Remedy" to life.
Epicureans: The first atheists
The Epicureans were some of history's first materialists. They believed that the world was made up only of atoms (and void), and that everything is simply a particular composition of these atoms. There were no gods, spirits, or souls (or, at most, they're irrelevant to the world as we encounter it). They thought that there was no afterlife or immortality to be had, either. Death is just a relocation of atoms. This atheism and materialism was what the Christian Church would later come to despise, and after centuries of being villainized by priests, popes, and church doctrine, the Epicureans fell out of fashion.
In the atomistic, worldly philosophy of the Epicureans, all there is to life is to get as much pleasure as you can and avoid pain. This isn't to become some rampant hedonist, staggering from opium dens to brothels, but concerns the higher pleasures of the mind.
Epicurus, himself, believed that pleasure was defined as the satisfying of a desire, such as when we drink a glass of water when we're really thirsty. But, he also argued that desires themselves were painful since they, by definition, meant longing and anguish. Thirst is a desire, and we don't like being thirsty. True contentment, then, could not come from creating and indulging pointless wants but must instead come from minimizing desire altogether. What would be the point of setting ourselves new targets? These are just new desires that we must make efforts to satisfy. Thus, minimizing pain meant minimizing desires, and the bare minimum desires were those required to live.
The Four Part Remedy
Given that Epicureans were determined to maximize pleasure and minimize pain, they developed a series of rituals and routines designed to help. One of the best known (not least because we've lost so much written by the Epicureans) was the so-called "Four Part Remedy." These were four principles they believed we ought to accept so that we might find solace and be rid of existential and spiritual pain:
1. Don't fear God. Remember, everything is just atoms. You won't go to hell, and you won't go to heaven. The "afterlife" will be nothingness, in just the same way as when you had no awareness whatsoever of the dinosaurs or Cleopatra. There was simply nothing before you existed, and death is a great expanse of the same timeless, painless void.
2. Don't worry about death. This is a natural corollary of Step 1. With no body, there is no pain. In death, we lose all of our desires and, along with them, suffering and discontent. It's striking how similar in tone this sounds to a lot of Eastern, especially Buddhist, philosophy at the time.
3. What is good is easy to get. Pleasure comes in satisfying desires, specifically the basic, biological desires required to keep us alive. Anything more complicated than this, or harder to achieve, just creates pain. There's water to be drunk, food to be eaten, and beds to sleep in. That's all you need.
4. What is terrible is easy to endure. Even if it is difficult to satisfy the basic necessities, remember that pain is short-lived. We're rarely hungry for long, and sicknesses most often will be cured easily enough (and this was written 2300 years before antibiotics). All other pains often can be mitigated by pleasures to be had. If basic biological necessities can't be met, then you die — but we already established there is nothing to fear from death.
Epicurus's guide to living is noticeably different from a lot of modern self-help books in just how little day-to-day advice it gives. It doesn't tell us "the five things you need to do before breakfast" or "visit these ten places, and you'll never be sad again." Just like it's rival school of Stoicism, Epicureanism is all about a psychological shift of some kind.
Namely, that psychological shift is about recognizing that life doesn't need to be as complicated as we make it. At the end of the day, we're just animals with basic needs. We have the tools necessary to satisfy our desires, but when we don't, we have huge reservoirs of strength and resilience capable of enduring it all. Failing that, we still have nothing to fear because there is nothing to fear about death. When we're alive, death is nowhere near; when we're dead, we won't care.
Practical, modern, and straightforward, Epicurus offers a valuable insight to life. It's existential comfort for the materialists and atheists. It's happiness in four lines.