David Boas, professor of biomedical engineering, Boston University

Functional magnetic resonance imaging (fMRI) is one of the great medical breakthroughs of the late 20th century. It allows doctors to track blood as it moves through the human brain, creating three-dimensional pictures of the mind as it operates. For the first time in history, doctors using fMRIs can actually see injury and illness in the brain — and hope to treat it.

However, the powerful electromagnets that power an fMRI scan make these machines heavy and immobile, not to mention expensive. Doctors can see how the brain works when it’s dressed up in a backless gown and lying on a table. But they can’t see how it lights up while trying to climb a set of stairs, remember an ATM code, or go out on a date. 

Boston University biomedical engineering professor David Boas would like to change that. And he’d like to do it with a beam of light.

“For the last 30 years, fMRI has done an amazing job of helping us understand the brain function of a person sitting inside a tube,” says Boas. “But what really makes us human is the social interactions, how we interact with the world around us. We have very little brain imaging data for those sorts of activities”

To make that happen, Boas and his team at Boston University are developing a way to scan the brain using just infrared light. Blood doesn’t tend to absorb light that shines at low- and medium-infrared wavelengths, Boas says. That makes it the perfect band for shining through skin and into the brain itself. By tracking how a patient’s blood scatters this light, a wearable brain scan can create a picture of how the brain has reacted to stimuli in the outside world.

Boas calls it functional near-infrared neurospectroscopy, or fNIRS, and he hopes that it will let doctors monitor brain activity in real time. 

“If you have a wearable imaging device, you can have a patient engage in normal behaviors,” says Boas. “While you’re trying to train a stroke survivor to walk again, you can figure out which physical therapy approaches are more effective than others. Likewise, with stroke survivors who are trying to speak again, you can have your clinical approaches to teach them to speak again while you measure the brain activity to see what works and what doesn’t.”

Boas hopes that his fNIRS techniques will help doctors, therapists, even people in their day-to-day lives. He says that this might happen in the decades to come, but is working to make it a reality today.