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Brain Stimulation, Recording Device Advances

Wand integrated circuits

Wand integrated circuits (Rikky Muller, Univ. of California in Berkeley)

2 Jan. 2019. An implanted device that both records activity and stimulates precise brain regions is shown to operate in lab monkeys, advancing its potential for neurological diseases. An engineering team at University of California in Berkeley and spin-off enterprise Cortera Neurotechnolgies describes the device in the 31 December issue of the journal Nature Biomedical Engineering (paid subscription required).

Researchers from the medical technologies lab at Berkeley led by electrical engineering and computer science professor Rikky Muller study implanted and wearable microsystems that monitor, diagnose, and treat brain disorders. To perform these functions, the lab’s devices are often miniaturized, wireless, and self- or remotely powered, with embedded intelligence. Among the conditions that these systems can address are epilepsy, where nerve cell activity in the brain is disturbed, causing seizures with symptoms ranging from blank stares to tingling sensations to loss of consciousness. Another target disorder is Parkinson’s disease that occurs when the brain produces less of the substance dopamine, a neurotransmitter that sends signals from one neuron or nerve cell to another, affecting muscle movements.

Up to now, implanted devices could either monitor or treat these disorders, but rarely do both, at least not effectively. Muller and colleagues are seeking a system that not only performs both recording and stimulating functions in the brain, but also tracks and stimulates more precise regions of the brain than current technologies. Today’s neural implants, say the authors, offer few channels and little flexibility, which limits their precision for diagnostics and stimulation. Also, sending out stimulation from implants often produces feedback that mixes with and disrupts monitoring of valid brain signals.

In addition, the researchers wanted a closed-loop device that can adjust stimulation patterns to meet the unique needs of the wearer at that moment, much like some pacemakers implanted to monitor and respond to heart rhythms. “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,” says Muller in a university statement. “And you can only do that by listening and recording the neural signatures.”

The miniaturized system designed by the Berkeley-Cortera team, known as wireless artifact-free neuromodulation device or Wand, monitors and data in 128 channels, far more than the 8 channels in most other closed-loop systems. The circuitry in Wand is trained to recognize an individual’s brain signal signatures, and respond with suitable stimulation if the signals deviate from normal patterns. At the same time, Wand can separate brain stimulation feedback from the individual’s brain signal signatures, since Wand already learned those signatures. “Because we can actually stimulate and record in the same brain region,” adds Muller, “we know exactly what is happening when we are providing a therapy.”

The researchers tested Wand devices implanted in the brains of rhesus macaques to recognize and delay specific arm movements with a joystick. In the proof-of-concept study, the rhesus macaques were first trained to move a cursor with the joystick to a specific location. At the same time, the Wand devices were trained to recognize those specific brain patterns, which then delivered electrical stimulation to delay those movements. Muller notes, “In the future we aim to incorporate learning into our closed-loop platform to build intelligent devices that can figure out how to best treat you, and remove the doctor from having to constantly intervene in this process.”

Muller, co-author and fellow Berkeley engineering professor Jan Rabaey, and others founded Cortera Neurotechnologies in 2013. Muller continues as the company’s chief technologist, while Rabaey serves on Cortera’s board. The company applied for a patent on the Wand device circuitry.

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