The Answer to Influencing Neural Activity May Be Found in the Body’s Chemistry

CAMBRIDGE, MA – Nearly 50,000 neurostimulators are implanted worldwide annually, bringing relief to many who suffer from neurological disorders ranging from Parkinson’s and epilepsy to chronic pain and depression. The current method of neurostimulation targets specific anatomical sites directly with tiny electrical impulses. Neuroscientists closely calibrate the electrical pulses and the nerves affected, but they have long sought more precise and flexible neural targeting. 

Now a team at Draper and the Massachusetts Institute of Technology (MIT) takes advantage of a well-known property of neurons—they respond to concentrations of the body’s own chemicals—to develop a novel therapeutic strategy with the potential to usher in new approaches to neurostimulation.

In their research, the engineers developed a neurostimulator with an ion-sensitive material (ISM) cuff that alters how the electrode stimulates the nerves around it. Rather than the direct electrical stimulation in a typical electrode, the ISM-coated neurostimulator changes the ion concentrations around it and elicits an electrochemical response that mimics how the body sends neural signals. 

Researchers tested the prototype on a frog’s sciatic nerve—the longest and widest single nerve in the body—and showed they could boost nerve response by adjusting calcium ion levels, and block nerve responses by adjusting potassium levels. Conventional electrodes can only block nerve responses. They also found that the device delivered a more precise targeting and needed less electrical energy for a response. 

The researchers caution that their work is still in its early stages, with ongoing proof of concept tests in frogs and rodents planned. However, the team says their work shows promise as a new type of nerve stimulation method for treating afflictions affecting the Vagus and sciatic nerves. They are interested in whether such a technique could one day be used to treat neurological conditions, such as Alzheimer’s disease and depression, and to expand the conditions treatable by Deep Brain Stimulation.

Matthew Flavin, a Draper Fellow and PhD student at MIT, said electrochemical neuromodulation shows promise as a therapy for a range of conditions. “There are techniques for blocking nerve activity using purely electrical signals, but there has long been discussion over the number of flaws related to the safety and stability of the devices. Our approach is more precise and more flexible. One of the things that makes this technology so promising is that it only requires a simple modification of any electrical stimulation platform. It could be a much more effective way of stimulating nerves that applies to a whole range of applications.”

In addition to Flavin, the research was conducted by Daniel Freeman, who is a senior research engineer at Draper, and Jongyoon Han, PhD Professor of Electrical Engineering and Professor of Biological Engineering at MIT. 

Draper’s ISM work could positively impact treatments for any condition caused by abnormal nerve response, several of which Draper is exploring within its biomedical work. Draper’s neurotechnology portfolio includes prosthetic technology that can give amputees a realistic sense of touch and limb awareness by using miniature implanted electrodes to record sensory and motor signals from individual nerve fibers of interest. Draper has also invested internal research and development funding to develop small biocompatible particles that could be implanted into the brain and body to enable non-invasive recordings of brain signals related to conditions like epilepsy, depression, and chronic pain.