DARPA Wants to Jolt the Nervous System with Electricity, Lasers, Sound Waves, and Magnets

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Illustration: Getty Images

Viewing the body as a chemical system and treating maladies with pharmaceuticals is so 20th century. In 21st century medicine, doctors may consider the body as an electrical system instead, and prescribe therapies that alter the electrical pulses that run through the nerves.

That’s the premise of DARPA’s newest biomedical program, anyway. The ElectRx program aims to treat disease by modulating the activity of the peripheral nerves that carry commands to all the organs and muscles of the human body, and also convey sensory information back to the brain.

Yesterday, DARPA announced the first seven grants under the ElectRx program. The scientists chosen are doing fairly fundamental research, because we’re still in the early days of electric medicine; they’ll investigate mechanisms by which to stimulate the nerves, and map nerve pathways that respond to that stimulation. They’re working on treatments for disorders such as chronic pain, post-traumatic stress, and inflammatory bowel disease.

The proposed stimulation methods are fascinating in their diversity. Researchers will not only stimulate nerves with jolts of electricity, they’ll also use pulses of light, sound waves, and magnetic fields.

Three research teams using electrical stimulation will target the vagus nerve, which affects many different parts of the body. IEEE Spectrum explored the medical potential of vagus nerve hacking in a recent feature article, writing: 

Look at an anatomy chart and the importance of the vagus nerve jumps out at you. Vagus means “wandering” in Latin, and true to its name, the nerve meanders around the chest and abdomen, connecting most of the key organs—heart and lungs included—to the brain stem. It’s like a back door built into the human physiology, allowing you to hack the body’s systems.

The light-based stimulation research comes from the startup Circuit Therapeutics. The company was cofounded by Stanford’s Karl Deisseroth, one of the inventors of optogenetics, the new technique that inserts light-sensitive proteins into neurons and then uses pulses of light to turn those neurons “on” and “off.” Under the DARPA grant, the researchers will try to use pulses of light to alter neural circuits involved in neuropathic pain.

To tweak the nervous system with sound waves, Columbia University’s Elisa Konofagou will use a somewhat mysterious ultrasound technique. In an e-mail, Konofagou explains that it’s already known that ultrasound can be used to stimulate neurons, but with the DARPA grant, she hopes to figure out how it works. Her hypothesis: As ultrasound propogates through biological tissue, it exerts mechanical pressure on that tissue, which stimulates specific mechanosensitive channels in neurons and causes them to “turn on.”

The final project will rely on magnetic fields to activate neurons, using a technique that could be called “magnetogenetics.” An MIT team led by Polina Anikeeva will insert heat-sensitive proteins into neurons, and will then deploy magnetic nanoparticles that bind to the surface of those neurons. When exposed to a magnetic field, these nanoparticles heat up and activate the neurons to which they’re attached.

Figuring out how to alter the activity of the nervous systems with these various tricks will be a pretty impressive accomplishment. But in the DARPA world, achieving that understanding is just step one. Next, the agency wants its grantees to develop “closed-loop” systems capable of detecting biomarkers that signal the onset of disease, and then respond automatically with neural stimulation. Spectrum covered the first such closed-loop neural stimulators in a recent feature article, stating: 

The goal of all these closed-loop systems is to let doctors take their expert knowledge—their ability to evaluate a patient’s condition and adjust therapy accordingly—and embed it in an implanted device.

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The Human OS

IEEE Spectrum’s biomedical blog, featuring the wearable sensors, big data analytics, and implanted devices that enable new ventures in personalized medicine.

 
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