In a proposed device, two of the new chips would be embedded in a chassis outside the head. Each chip could monitor electrical activity from 64 electrodes in the brain while delivering electrical stimulation to prevent seizures or tremors.

A neurostimulator developed by engineers at the University of California, Berkeley, can simultaneously listen to, record, and stimulate electric current in the brain, potentially delivering fine-tuned treatments to patients with diseases such as epilepsy and Parkinson’s.

These devices prevent tremors or seizures in patients with various neurological conditions. However, electrical signatures that precede a seizure or tremor can be subtle, and the frequency and strength of electrical stimulation required to prevent them equally touchy, often taking years for doctors to optimize.

The wireless artifact-free neuromodulation device (WAND) recognizes signs of tremors or seizures, and can automatically adjust stimulation parameters in real-time.

“We want to enable the device to figure out what is the best way to stimulate for a given patient to give the best outcomes. And you can only do that by listening and recording the neural signatures,” says Rikky Muller, assistant professor of electrical engineering and computer sciences at Berkeley.

The WAND chip’s custom integrated circuits can record the full signal from subtle brain waves and strong electrical pulses delivered by the stimulator.

Closed-loop design

WAND can record electrical activity using 128 channels, measuring 128 points in the brain, compared to eight channels in other closed-loop systems. Today’s deep brain stimulators either stop recording while delivering the electrical stimulation, or record at a different part of the brain from where the stimulation is applied.

“(To) deliver closed-loop stimulation-based therapies, which is a big goal for people treating Parkinson’s and epilepsy and a variety of neurological disorders, it is very important to perform neural recordings and stimulation simultaneously,” says former UC Berkeley postdoctoral associate Samantha Santacruz, now an assistant professor at the University of Texas in Austin.

Researchers at Cortera Neurotechnologies Inc., led by Muller, designed the WAND integrated circuits to record subtle brain waves to strong electrical pulses. So, WAND can subtract the signal from the electrical pulses, measuring a clean signal from the brain waves. Existing devices are tuned to record signals only from the smaller brain waves and are overwhelmed by large stimulation pulses.

Working with Electrical Engineering and Computer Science Professor Jan Rabaey’s lab, the team built a platform device with wireless and closed-loop computational capabilities that can be programmed for research and clinical applications.

In experiments led by Santacruz, and Electrical Engineering and Computer Science Professor Jose Carmena, subjects used a joystick to move a cursor to a specific location. After training, WAND detected the neural signatures that arose as subjects prepared to perform the motion, and delivered electrical stimulation that delayed the motion.

WAND’s custom integrated circuits.

“While delaying reaction time is something that has been demonstrated before, this is, to our knowledge, the first time that it has been demonstrated in a closed-loop system based on a neurological recording only,” Muller says.

In the future, researchers want to build intelligent devices that best treat patients, removing doctors from having to constantly intervene.

UC Berkeley