Diamonds in the Mind
Despite decades of studying electrical brain stimulation, scientists still don’t fully understand how it affects the networks of the 100 billion neurons in the brain. One researcher at the University of Pittsburgh is building diamond-based wireless electrodes to uncover how these networks translate into sensations— and how to use that knowledge to better treat neurological conditions.
Takashi Kozai, associate professor of bioengineering and Ernest E. Roth faculty fellow at the Swanson School of Engineering, in collaboration with Michigan State University’s Wen Li, received a 5-year, $3.4M R01 grant from the National Institutes of Health (NIH) to develop advanced brain stimulation technology using lab-grown diamonds.
Kozai’s project, “Mechanisms of localized neuronal excitation with diamond Wireless Axon and electrical microstimulation,” aims to engineer both hardware and stimulation software for better understanding and treating neurological conditions by developing diamond "Wireless Axon" electrodes for use in intracortical microstimulation.
“One of our aims is to look at how electrical brain stimulation impacts different groups of neurons.” Kozai said. “When we electrically stimulate sensation in the brain, we want to know more about how the neuron groups act when we activate them. If we electrically stimulate someone’s brain and they feel pressure or cooling or warming sensations, we're trying to investigate what different groups of neurons are being activated.”
Conventional electrical brain stimulation typically activates a sparse and distributed population of neurons. To improve neuronal targeting, the team will be using photovoltaics — or light-driven stimulation — which lets them stimulate neurons with voltage rather than with electrical current. This approach allows them to activate a more specific population of neurons by selectively activating the neuron’s cell body instead of its surrounding axons.
“We've been working with a couple of folks who make diamond electrodes with various impurities and dopants, which allows us to drive their activity at different efficacies.” Kozai said. “Because the devices we’re building are wireless, they’re not moving every time someone has a heartbeat or brain movement. This gives us a new level of control and helps avoid common issues with electrodes like glial scarring in the brain.”
The diamonds are doped with the chemical element boron—a process that involves intentionally adding impurities to a material to modify its electrical conductivity—allowing the team to enhance the conductivity of the diamonds and generate voltages more efficiently. Kozai’s team will study how different amounts of boron impact the electrode’s function, and ultimately hope that these more efficient electrodes will provide deeper insights into the inner workings of the brain.
“A few groups around the world have been doing intracortical stimulation to restore sensation, but it’s amazing that despite using these tools, we still don’t fully understand what they’re actually doing to populations of neurons in the brain.” Kozai said. "Once we understand that, we can begin adapting it into therapies, treatments, and even cures for neurodegenerative conditions, sensory loss, and paralysis."