For reasons we'll soon explain, turning on a light inside a mouse's head can help scientists map brain function. It's easy to implant an LED in a mouse's brain, but how to power it? Until now, the mice either needed to be tethered to a fiberoptic cable or fitted with heavy wireless charging devices. However, Stanford scientists managed to build an implant that's not only lightweight, but able to receive consistent amounts of wireless energy.
How can light change brain function? Using "optogenetics," scientists can genetically alter neurons with green algae genes to make them responsive to light. By modifying only select parts of the brain, researchers can see how those regions affect behavior. The Stanford team created peppercorn-sized implants that contain a power receiving coil, circuit and LED, all weighing a nearly negligible 20 to 50 milligrams. When the mouse is placed in an electromagnetic chamber, the implant coil harvests RF energy to power the light, which in turn stimulates the targeted brain region.
To prove that the wireless implants worked, the researchers tested them on neurons and spinal cord nerves. When the system is powered on, the mouse walks in circles, as shown in the video below. When the power is shut off, the behavior stops, proving that the concept works. Further experiments could lead to insight on neurological conditions like Parkinson's disease, blindness or mental health issues. The research also gives new meaning to the term "wireless mouse" (sorry).