Researchers at the University of Glasgow have, for the first time in history, passed a photon of light through the brain of an adult human—from one temple to the other. This was made possible by using the cerebrospinal fluid as a kind of light-guiding “corridor.” The study opens the way to new, non-invasive diagnostic methods for deep brain areas.
Until now, optical methods could only “look” into the head by a few centimeters, and only the brains of infants were amenable to such analysis. The Glasgow team assembled a setup including an ultrafast laser and a sensitive detector, and recorded the passage of light through the skull. One photon per second was enough to prove that light reaches even the deeper, previously inaccessible layers of the brain.
The method is currently applicable only to light-skinned volunteers with no hair and requires complete darkness and long data collection sessions. Nevertheless, it is the first step toward a future where diagnosis of strokes or tumors could become available directly in an ambulance or at home—without a CT scanner and without operations.
