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Healing Wounds, Visible and Invisible

From prosthetics to PTSD, Viterbi researchers advance the future of veterans’ care
November 12, 2012 —

War is its own kind of trauma. Days filled with strict regimented rules of behavior, constant travel, friends killed in roadside bombings and personal injuries: coming home to American life can be a great shock. Nathan Graeser, a U.S. Army National Guard Chaplain, often gets calls in the middle of the night from returning soldiers he’s seen at his Burbank office. “For one soldier, things would be frustrating that were never frustrating before,” recalls Graeser. “When he got back, things people complain about in America seemed so trivial.”

Two point four million Americans have fought in Afghanistan and Iraq since 2003; that’s 2.4 million stories, and none of them are quite the same. For some veterans, it may take years to figure out how to deal with a missing limb, chronic pain or “invisible wounds”, and oftentimes, not without dramatic disruptions to their families, careers, and even their own identity. The U.S. Department of Veterans Affairs has been dealing with reintegration issues for decades—since 1930—providing access to medical care, therapy, and amputee rehabilitation programs through offices around the country.

Now, the USC Viterbi School of Engineering is busy bringing the latest technological innovations to bear on the reintegration issues soldiers face. Things like upgraded prosthetics and virtual humans are the future of vet care, and will one day be a tremendously useful resource to places like the VA in their ongoing efforts to support returning soldiers mentally and physically.


Dr. Gerald Loeb

If you think technology and wounded soldiers, one thing that might come to mind is prosthetics. In the movie “The Empire Strikes Back,” Luke Skywalker loses his hand in battle with Darth Vader, is fitted with a futuristic prosthetic and goes on to brandish a lightsaber with great dexterity. But it’s sci-fi, not science. In reality, prosthetics are difficult to develop because there are so many steps involved in moving a limb: from the brain to the muscles to the fingertips.

“At every level, if you mess something up, other things will not work,” says Dr. Gerald Loeb, who, from a basement lab at USC Viterbi Denney Research Building, is revolutionizing the science of prosthetics. Along with other researchers that are part of the DARPA Repair Program (a new DoD technology initiative), Loeb has now set his sights on helping soldiers, veterans, and others have full use of their limbs again by modeling the way muscles work normally and making improvements on current technologies.

Loeb’s most recent triumph is tactile sensing: making prosthetics fingers feel. Dr. Loeb’s BioTacs, silicone rubber pads anchored to the end of metal prosthetic fingers, can detect pressure, temperature, and vibration on contact, which helps the arm sense what kind of material is being touched and how much grasping pressure needs to be applied. Apply too much pressure, and you crush a soda can or cell phone. Loeb’s fingertip sensors are trained to stop a grasping motion like a reflex, before it crushes an object. This is a vast improvement over other modern prosthetics with which the user has to pay an inordinate amount of visual attention to the fingers and train muscles connected to the prosthetic to pick the exact moment to stop grasping.

Loeb funded the technology’s development through SynTouch, a small Viterbi spinoff company he started with a grant from the National Institute of Health. Similar sensors are being developed at Johns Hopkins University Applied Physics lab as well. It’s cutting edge technology. But, Loeb is not new to innovation— he started his career as one of the inventors of the most successful neural prosthetic in history: the cochlear implant.

“As a medical doctor by training and an engineer by instinct, I can't resist any opportunity to fix a medical problem with technology when available,” say Dr. Loeb.

Slide-on arms and legs allow for muscle stimulations to trigger movement, but the future of prosthetics lies in wiring a part of the machine directly to the brain. Researchers at Duke University have implanted electrodes in monkeys’ brains that allow them to move a virtual prosthesis using mind-power. But, just down the hall from Dr. Loeb, Dr. Ellis Meng is revamping these electrodes so they can live in the brain permanently and provide a lasting solution for amputees.

Dr. Ellis Meng
For the past year, as a part of DARPA-funded research, Dr. Meng has been busy building electrodes that better integrate into the brain, the key to getting a long-lasting signal to a prosthesis. To do this, she constructed a device with an entirely new shape and new physical properties. In the course of research, Meng built a tiny hollow sheath of soft polymer material, tacked on tiny electrodes on its outer and inner face, and coated it with chemicals that stimulate neuron growth and discourage harmful immune responses in the brain. When the device is implanted, neurons grow around and inside of it, and their proximity helps to maintain a strong recording signal over time. All other existing electrode devices are made of a rigid core, which encourages cell death around it. Because of lost signals, most modern devices have to be replaced every one to two years. Dr. Meng’s soft polymer electrodes could potentially live there for decades.

“Hopefully, this will be the next generation of electrodes,” says Dr. Meng, named one of the Top 40 Innovators Under 40 this year by MD + DI. The new electrodes are working beautifully so far, and Dr. Meng has just begun testing in rats.
Implantable three dimensional polymer sheath neural probe
In addition to building better prosthetics systems, Dr. Loeb and Dr. Meng also both work on other realities of returning home from war: chronic pain and, at least among paralyzed vets, an increased risk of infection. Several years ago, Dr. Loeb invented a tiny electrical stimulator called a BION that can be injected into little-used muscle tissue of wheelchair patients to keep the tissue from atrophy.

“When you talk to someone who has a spinal cord injury about what really bothers them, it’s not that they can’t walk, it’s that they’re afraid of dying of infection,” says Dr. Loeb. “Chistopher Reeve essentially died of such complications.” Dr. Loeb’s BIONs lodge in the unused muscles tissue of paralyzed patients and are stimulated at regular intervals by a wireless device clipped to the patient’s wheelchair. The twitching muscles shift the weight of the patient from side to side occasionally, so they won’t develop sores from disuse. The BIONs have been tested and proved successful in a handful of patients so far.

Also, chronic pain can be a problem for injured veterans. Dr. Meng has made major improvements on existing implantable medication pumps, tiny drug chambers with pumps and tubes attached that deliver medication throughout the day to chronic pain sufferers. Dr. Meng’s pumps use wireless coupling to transmit power to the devices instead of batteries, which makes them smaller and more than doubles their lifetime. Her lab has also worked to make the pumps more reliable; commercial pain pumps never turn off, so if they malfunction, there is a risk that a large pool of drugs is dumped into the patients system at once. Dr. Meng’s pumps turn off automatically between drug dosing and so are much safer. These pumps are very important to some people’s ability to function day to day.

“Veterans are really dependent on this to live some semblance of a normal life,” says Dr. Meng. The pain pumps will enter animal studies within the next year.


Roadside bombs and enemy fire can send a soldier home with a missing arm or leg. But, living with the constant threat of violence is such a stark contrast to civilian life; like with any trauma, it’s hard to readjust mentally.

“In war, you start to live above self-preservation and you turn off the parts of you that make you a real person to do it,” says Army National Guard Chaplain Graeser. “And, that’s not how it works when you end up in the real world.”

Dr. Louis Phillipe Morency
Between 12 and 25 percent of soldiers come back from Iraq or Afghanistan with symptoms of PTSD and need professional counseling. But, they are hesitant to get help; often veterans live in rural areas, far from access to a specialist, or just feel too ashamed to get care. To fill in the gaps, Dr. Louis-Philippe Morency at USC’s Institute for Creative Technologies (ICT) is working on a virtual human for healthcare support. Called SimSensei, it aims to be a tool that veterans can access from their home computer that serves as an anonymous first step towards seeking help. The research project is a part of the DARPA Detection and Computational Analysis of Psychological Signals (DCAPS) program.

To create a believable and empathetic human interaction, Dr. Morency, a Viterbi research assistant professor in computer science, collaborates with ICT psychologist Dr. Skip Rizzo (who has a long history of partnership with Viterbi engineers) to tweak SimSensei’s questions, answers, and body language. On a computer in Dr. Morency’s office, you can see a female SimSensei listening to a participant’s story, nodding while they talk, and responding with vague yet relevant comments like “I can see that this topic upsets you,” or “Would you like to talk more about this?”

To make the virtual human an effective tool, Dr. Morency has designed an algorithm on the backend of the software that can measure veterans’ behavioral cues and correlates them with their likely psychological state. For instance, Morency’s team has found that when people are distressed, they express smiles less prominently and for shorter durations, fidget with their hands more, often and look down for longer periods of time. SimSensei automatically recognizes these cues while the participant is telling their story. The techs operating SimSensei have access to graphs of the participant’s behavioral metrics, which they can watch change as he or she speaks. Currently, eight of these metrics, taken together, can provide feedback to the veteran, including recommendations to seek counseling.
ICT's SimSensei, a virtual human for health care support
“The real goal is you want the soldier, if they have any kind of distress, see a clinician, at least call someone, do something, so we’re trying to build some steps so that they get there,” says Dr. Morency, who was named one of IEEE’s “10 to Watch for the Future of Artificial Intelligence” in 2008. SimSensei is currently tested on videos of veterans telling war stories, sourced from the U.S. Veterans site in Long Beach, but evidently, it’s been very popular in the office, too. Dr. Morency has caught many test subjects divulging more of their personal thoughts to it than they anticipated.

Dr. Shrikanth Narayanan
Dr. Shrikanth Narayanan, Andrew J. Viterbi Professor of Engineering, who helped pioneer the development of algorithms for behavioral signal processing from his former post at AT&T Bell Labs, is now at USC Viterbi working on technology-mediated counseling, too. Here, his Signal Analysis and Interpretation Laboratory has won three major InterSpeech Challenge awards in the last four years, an impressive feat. Dr. Narayanan focuses on detecting and gathering information about people’s psychological state from not only video, but physiological cues and audio, as well.

The telephone is an easy way for veterans to get access to a professional between visits, but without visual cues, it’s often more difficult for a counselor or VA worker to assess a veteran’s state of mind. Dr. Narayanan’s algorithms can pick up on fine details in a person’s speech that counselors would miss. For example, how long someone speaks belies how engaged they are, pauses at certain times can indicate a feeling of discomfort, heightened loudness of the voice can betray anger, and a more monotone rhythm in speech can indicate withdrawal. Also, the content of what people actually say can be analyzed by what’s called lexical analysis, where words like “no” and repeated questions might indicate frustration, for example. Dozens of variables, taken together, can provide a clinician an exact quantitative measure of distress to supplement any personal judgment they might make about an encounter. When possible, such information from audio, when combined with video can offer further insights into a person’s behavioral state.

“Can these technologies replace psychologists? The answer is a big no,” says Narayanan. “They’re meant to fill in the dots between formal clinical encounters.” To test his algorithm, Narayanan works with distressed families in general rather than veterans specifically, but looks forward to working with this population in the near future.

There is some question as to how comfortable veterans will be with using technology for mental health purposes. Privacy is of the utmost importance; soldiers will want to be reassured that their digital encounters are theirs and will only be shared at their discretion. But, Army National Guard Chaplain Graeser thinks the technology could catch on.

“If I had a dollar for every time I tried to call a soldier and they texted me an issue,” says chaplain Graeser. “They are products of their generation as well. I think you meet people where they’re at, that’s the point of help.”


For the USC Viterbi School, technology is all about “meeting people where they’re at.” Technology is becoming more and more pervasive in American life. And, with their long history of collaboration and entrepreneurship within and outside of USC, Viterbi engineers are focused on getting their technologies out in the world so they can help people as soon as possible.

“I want to make sure that technologies that I work on are not orphaned in the academic lab and make it into the hands of patients,” says Dr. Meng. “So I spend a great deal of time making sure that my research is relevant to and well-matched with the needs of tough, unsolved medical problems.”

With roughly 500 veterans in the existing USC student population, veterans issues have long been a part of university history, going back to the thousands of enrollees in the post World War II era. Just last March, USC trustee William J. Schoen ’60, MBA ’63 and his wife, Sharon, made a $10 million gift to the university in support of military veteran scholarships. The gift provides additional support for veterans studying at the USC Marshall School of Business, as well as the USC Viterbi School of Engineering.

As their research shows, Viterbi engineers are committed to bringing these helpful technologies to fruition for veterans, specifically.

“I think all patients who have suffered an injury or disease deserve the best society has to offer,” says Dr. Loeb. “This is especially true for those who have become disabled in the course of contributing directly to our society."