The mesh unrolls like a loosed parachute—not into thin air but rather into the brain of an unconscious mouse.
Delivered from the tip of a syringe, the device is woven from supple, electricity-conducting fibers half as thick as a human hair. Nestled among neurons deep within the mouse’s gray matter, this nanowire fabric gives researchers at Harvard University a way to record—and even alter—the ebb and flow of signals to individual neurons in a living brain.
To understand how the brain works, researchers need ways to measure it in action. Tracking the fine-grained firing of individual neurons is a tantalizing yet unrealized path to answering big questions about the complex workings of the brain. Electrodes in direct contact with brain cells can take precise measurements, but traditional rigid electronics are cumbersome and invasive.
The Harvard team’s flexible, 2D mesh consists of strands of polymers organized in a fishnet-like pattern. At each crisscross, there’s a tiny electrical component to send or receive signals. Unrolled, the mesh is roughly 20 times as wide as the size of the opening from which it emerged. The researchers recorded from 16 individual neurons in the hippocampus, a brain region associated with spatial recognition, to verify their device. They also used the injected mesh to send signals to individual neurons. Here’s Elizabeth Gibney, reporting for Nature News:
The implant has the potential to unravel the workings of the mammalian brain in unprecedented detail. “I think it’s great, a very creative new approach to the problem of recording from large number of neurons in the brain,” says Rafael Yuste, director of the Neurotechnology Center at Columbia University in New York, who was not involved in the work.
The Harvard group observed their wired-up mice for five weeks after the mesh injection, watching out for possible immune responses to the foreign material in the mouse brains. They are hopeful the technology may indeed be extended to record many more neurons over much longer periods of time.
At present, researchers have a direct line to a dozen or so cells in the brains of unconscious mice, but they have even bigger dreams for future developments. Though much more testing is needed, this technology may someday allow the researchers to stimulate individual neurons therapeutically, counteracting the ravages of strokes or diseases like Parkinson’s.