Mice Can Now Swim and Compete While Their Brain Cells Are Recorded

A group at Tsinghua University has built a head-mounted microscope that weighs 1.0 gram and sends its data out wirelessly, and used it to watch brain cells in mice while the animals swam, explored mazes and competed with each other. The work was published Oct. 19, 2026, in Nature.

Microscopes small enough for a mouse to carry have had to be tethered by a cable and could cover only a narrow patch of brain, which limits what an animal is allowed to do while it is being recorded. The authors state that their device, which they call Airscope, makes it practical to record from several naturally behaving animals at once.

The team reports that Airscope resolves features down to 4 micrometers across a field of view 6 millimeters wide, at 12.5 frames a second, and that its wireless link carried calcium imaging, which tracks the flashes of light cells give off as they fire, from more than 8,500 neurons in a single animal. The paper gives that count as a 25-fold increase, and credits a lens design whose optical stack is 2.84 times shorter than in previous miniaturized microscopes.

On what the instrument recorded, the authors report patterns of activity in the cortex, the brain's outer layer, that correlate with behavioral signs of social dominance, and population activity that decoded in advance which of two paired mice would win a contest. They also report activity tied to reward locations as mice explored a maze and, with two devices on one animal, a directional influence running from the spinal cord to the cortex during fear conditioning.

The first author is Yuanlong Zhang and the senior author is Qionghai Dai, both at Tsinghua University. The group also includes researchers at Fudan University, Princeton University, Northeastern University in Shenyang and the Chinese PLA General Hospital in Beijing.