Embedding minuscule glass tubes inside a mouse brain allows neuroscientists to monitor brain activity over long periods of time, watching neurons and tissue change with illness or aging. The method, developed at Stanford University, opens a porthole into the brain's deepest recesses.

Whole-brain scans like functional magnetic resonance imaging allow scientists to watch brain activity unfold, but they don’t provide the level of detail you might need to watch degenerative diseases or cancer at work. Traditional light microscopes can only go so far, however, penetrating about 1/32 of an inch of tissue before it’s too dark to see. Scientists have been able to peer deeper by using micro-optics, but this is also just a snapshot of one moment in time, and it’s almost impossible to return to the same spot twice. What’s more, the act of taking a peek — shoving a micro-optical device deep into the brain — can cause injury or infection.