The living brain has always been a tricky thing to study. How do you figure out what's going on without poking, prodding, and jostling the brain so much that it's not working right? A relatively non-invasive new technique developed by neuroscientists at Stanford and Massachusetts General Hospital uses a laser and fluorescent carbon nanotubes to look at the web of tiny blood vessels in the brain.
In mice, the technique can be used to visualize blood in even the tiniest blood vessels just microns in diameter. Diseases like stroke, migraines, and Alzheimer's all affect blood flow in the brain. Current techniques for tracking blood flow are either more invasive (popping off a piece of the skull, for example) or at a lower resolution (CT, MRI).
To start, the team injected mice with carbon nanotubes. By shining a near-infrared laser that on fluorescent nanotubes, they could track blood coursing through the brain. Those nanotubes were specially designed to exhibit fluorescence at long wavelengths that could penetrate through intact bone and scalp. The mice did need a bit of a shave, but their heads stayed otherwise unharmed. The downside is, of course, that the laser still doesn't penetrate that deep, only about three millimeters, which makes imaging larger brains like humans a good deal more difficult.
For now, it's a cool new way to look at how mouse brains work—both when they're functioning normally, and when they have a mouse version of Alzheimer's or a stroke. [Stanford]
Images courtesy of Dai lab