How does the human brain, a collection of nearly 100 billion densely packed nerve cells, allow us to think, feel, act and perceive the world?

Scientists at Yale University’s Brain Function Lab are trying to better understand what happens in our brain during a conversation, using skullcaps connected to 64 cables.

At the tip of half of those fiber optic cables, weak laser beams slip through the wearers’ skulls and penetrate about 2.5 cm into their brains. There, the beams bounce off, reflect back and are picked up by the other half of the cables.

Scientists obtain detailed brain images with bright blotches of colour indicating where the action is taking place. It’s not a direct picture, like an X-ray, but rather a reconstruction.

“We want to understand the neuro circuitry that is associated with interaction between individuals,” explains neuroscientist Joy Hirsch, director of the Yale Brain Function Lab. “It’s probably one of the most fundamental functions of the human species