Researchers at the University of Arizona have developed an advanced optogenetics device that can stimulate multiple areas of the brain at once and control the intensity of emitted light. The miniaturized device is wireless and battery-free, and the researchers hope that it will pave the way to treating severe neurological disorders and controlling chronic pain.

Optogenetics involves loading specific neurons with proteins called opsins, which can stimulate a neuron to fire when exposed to light. At present, the technique is primarily a research tool to help scientists work out how the brain operates. “We’re making these tools to understand how different parts of the brain work,” said Philipp Gutruf, a researcher involved in the study. “The advantage with optogenetics is that you have cell specificity: You can target specific groups of neurons and investigate their function and relation in the context of the whole brain.”

However, the technique also has enormous therapeutic potential. For instance, in the future clinicians could use it to activate neurons to restore movement in paralyzed patients, or deactivate neurons that cause pain. However, accurately and conveniently administering light to the brain has posed a hurdle.

To date, optogenetic devices have been bulky, visibly protruding from the skull, and have only allowed researchers to stimulate one area of the brain at a time. In addition, altering the frequency or intensity of the administered light has not been possible, limiting the level of control that a clinician might exert.

This new optogenetic device addresses those shortcomings, and could help pave the way for clinical applications. “We were able to implement digital control over intensity and frequency of the light being emitted, and the devices are very miniaturized, so they can be implanted under the scalp,” said Gutruf. “We can also independently stimulate multiple places in the brain of the same subject, which also wasn’t possible before.”

By tuning the intensity of the light emitted by the device, the researchers can control which neurons it affects, as more intense light will penetrate deeper into the tissue. The device is wire- and battery-free, is powered by external oscillating magnetic fields, and can be implanted during a simple surgical procedure.

The researchers claim that the device shouldn’t fail over time in the body, meaning it wouldn’t need to be replaced regularly, unlike existing implantable devices such as pacemakers. “In the future, this technique could provide battery-free implants that provide uninterrupted stimulation without the need to remove or replace the device, resulting in less invasive procedures than current pacemaker or stimulation techniques,” said Gutruf.