A multi-campus research team has developed a new device to noninvasively measure cervical nerve activity in humans. The device, described in an article by Scientific reportshas potential applications to support more personalized treatments for sepsis and mental health conditions such as post-traumatic stress disorder (PTSD).
“With this newly developed device, we (for the first time) identified cervical electroneurographic evidence of autonomic biotypes (fight or flight versus rest and digest) that were remarkably consistent across different autonomic or involuntary nervous system challenges,” said the lead author of the study. Imanuel Lerman of the Qualcomm Institute, UC San Diego Jacobs School of Medicine and Engineering, and the VA Center of Excellence for Stress and Mental Health.
The device features a flexible array of electrodes that stretch from the lower front to the upper back of the neck, allowing researchers to capture electrical activity on different nerves. Other features include an integrated user interface to visualize data in real time and a custom algorithm to group people based on their nervous system response to stress.
A safer, less invasive way to study the nervous system
In the past, the most reliable ways to measure nerve activity in the neck required surgically implanted microelectrodes.
Lerman and Todd Coleman of the Jacobs School at UC San Diego and Stanford University set out to create a less risky and invasive way to monitor this part of the nervous system by adapting existing technology that Coleman had developed with co -author Jonas Kurniawan, now a postdoctoral fellow at Stanford. The new flexible array can be worn for up to a day and moves easily with the movements of the patient’s head and neck for longer, painless monitoring.
To explore human autonomic biotypes, or groups of patients whose involuntary nervous systems responded similarly to stress, the researchers performed a series of tests that asked study participants to place and hold their hand in water, followed by a timed breathing exercise. The electrode array recorded cervical nerve signaling, called cervical electroneurography by the team, and heart rate in the subjects before and after the ice-water challenge and during the breathing exercise.
The researchers found that study participants consistently fell into two distinct biotype groups: those whose neural firing and heart rate increased during both tests, and those who exhibited the opposite trend. The device’s unique algorithm also provides the ability to identify differences in the response of specific nerve groups to stressors such as ice-water challenge-induced pain and physical symptoms including sweating. and increased heart rate, associated with the timed respiratory challenge.
“The results are exciting. Our newly developed sensor array has been shown to be able to record autonomic nervous system activity,” Coleman said. “We were pleasantly surprised to observe a consistent autonomic response across all stress test challenges, i.e. the cold presser test and the deep breath challenge. More work is needed to demonstrate our sensor capabilities in larger populations.”
Towards a future of personalized medicine
Although the electrode array can’t pinpoint the exact nerves that fire in response to stress and pain from the cold water challenge, researchers hope it will one day help diagnose and treat conditions like this. as PTSD and sepsis.
The vagus nerve, for example, triggers inflammation in response to injury or infection in the body, a mechanism that can be disrupted by PTSD. Lerman and his colleagues hope their new device may one day help clinicians measure patient response to PTSD treatment, such as deep breathing exercises used during mindfulness meditation, by monitoring neural firing in the vagus nerve. Already, Lerman is one of several researchers using electrical stimulation of the vagus nerve to test whether stimulating these neural structures can reduce inflammation and pain in people with PTSD.
In a related application, the network can also be used to promote the safety of pilots flying military aircraft by detecting bursts of nerve activity that cause dizziness or nausea.
In a hospital setting, the device could help flag patients at risk of life-threatening conditions like sepsis by identifying people who react strongly to physical stress. Sepsis occurs when the body’s immune system overreacts to an infection, damaging its own tissues. The risk of death increases by seven percent every hour. Technology that helps detect and flag at-risk hospital patients would provide doctors advance notice of antibiotic administration, improving a patient’s chances of avoiding or surviving sepsis.
As a next step, the researchers plan to integrate the network with additional hardware for a portable wireless sensor that can be deployed outside the lab. The researchers are now moving forward with a clinical trial to detect sepsis in the hospital.
This study was a multi-pronged effort between researchers at UC San Diego Qualcomm Institute, School of Medicine, Jacobs School of Engineering (Departments of Electrical and Computer Engineering, Materials Science and Engineering, Nanoengineering, and Bioengineering), Department of Physics and Herbert Wertheim School of Public Health and Human Longevity Science, Stanford University and San Diego Veterans Health System. Funding was made possible by the Biomedical Advanced Research and Development Authority and the David and Janice Katz Neural Sensor Research Fund in Memory of Allen E. Wolf.