Scientists inserted a window in a man's skull to read his brain with ultrasound

A close up on a brain scan with one portion highlighted in red, indicating the location of an implant.

In a first, scientists have used ultrasound waves to peer inside a person's brain. The man's brain activity was recorded as he completed tasks outside a medical facility, including playing a video game. 

To achieve this feat, researchers implanted a material into the man's skull that allowed ultrasound waves to pass into his brain.