A new thumbnail-sized microscope will give researchers a way to see what’s happening in the brain of a mouse as it moves around and goes about its business. The microscope, described earlier this week in Nature Methods, weighs less than 2 grams—little enough that it can be fitted atop a rodent’s head—and tracks the activity of up to 200 brain cells.
To watch a living brain in action, researchers usually have to make sure the animal that brain belongs to is keeping very still, be it a human in an
MRI machine or a mouse under a benchtop microscope. That’s not such a problem for researchers studying, say, vision or memory—but it’s difficult to investigate the neuroscience of movement or behavior when your subjects can’t move around and behave.
The new device is a fluorescence microscope, meaning it shines light on a sample, then captures the glow that bounces back. Despite the scope’s tiny size, the researchers fit all the necessary optical components—lenses, sensors, a mirror, an LED light, and more—inside it. In addition to being mobile, the microscope captures the activity of more cells than a traditional benchtop microscope does, letting researchers see what’s happening in a larger area of the brain.