Sleepy rat

Cocaine-addled rats sobered up with wireless brain implant

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Researchers from the Korea Advanced Institute of Science and Technology (KAIST) have developed a brain implant that can be recharged and controlled wirelessly using a smartphone.

The brain implant can be used to control brain circuits for long periods of time without a battery replacement thanks to wireless charging.

The device is constructed from ultra-soft, bio-compliant (will not degrade after being surgically implanted into the body) polymers, providing long-term compatibility with brain tissue. They are fitted with micrometre-scale LEDs on ultra-thin probes, which can manipulate target neurons in the deep brain using light stimuli.

The device is a significant leap forward from the 2019 wireless head-mounted brain implant which preceded it.

Both are designed to deliver various types of drug and light stimulation treatments wirelessly via smartphone. Wireless implantable devices address a major limitation of current brain implants; tethered implants cause stress and inflammation in freely-moving animals during studies, shortening the lifetime of the devices. However, these devices require regular surgeries to replace depleted batteries or bulky and inconvenient wireless power setups.

“This powerful device eliminates the need for additional painful surgeries to replace an exhausted battery in the implant, allowing seamless chronic neuromodulation,” said Professor Jae-Woong Jeong, who developed both devices.

“We believe that the same basic technology can be applied to various types of implants, including deep brain stimulators, and cardiac and gastric pacemakers, to reduce the burden on patients for long-term use within the body.”

Jeong and his colleagues enabled wireless charging and controls using a tiny circuit which integrates a wireless energy harvester with a coil antenna and Bluetooth low-energy chip. Alternating magnetic fields harmlessly penetrate tissue, charging the battery. The battery-powered Bluetooth implant can then deliver programmable patterns of light to neurons via a smartphone app, allowing real-time control of brain circuitry.

“This device can be operated anywhere and anytime to manipulate neural circuits, which makes it a highly versatile tool for investigating brain functions,” said Choong Yeon Kim, lead author of the Nature Communications study.

The researchers tested their newest device in rats, demonstrating their ability suppress erratic behaviour after the rats were injected with cocaine with precise light stimulation of relevant target neurons. The batteries were charged multiple times while the rats were roaming freely, minimising interruptions to the experiment.

“The fact that we can control a specific behaviour of animals, by delivering light stimulation into the brain just with a simple manipulation of smartphone app, watching freely moving animals nearby, is very interesting and stimulates a lot of imagination,” said Professor Jeong-Hoon Kim, a physiologist at Yonsei University. “This technology will facilitate various avenues of brain research.”

The researchers hope that the brain implant could open up new opportunities for brain research and therapeutic intervention to treat disease in the brain.

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