New optical approach

This new approach to brain scanning is ideally suited for children and for patients with electronic implants, such as pacemakers, cochlear implants and deep brain stimulators.

Scientists have advanced a brain-scanning technology that tracks what the brain is doing by shining dozens of tiny LED lights on the head. This new generation of neuroimaging compares favorably, while avoiding the radiation exposure and bulky magnets other approaches require, according to School of Medicine research.

The new optical approach to brain scanning is ideally suited for children and for patients with electronic implants, such as pacemakers, cochlear implants and deep brain stimulators (used to treat Parkinson’s disease). The magnetic fields in magnetic resonance imaging (MRI) often disrupt either the function or safety of implanted electrical devices, whereas there is no interference with the optical technique.

The new technology is called diffuse optical tomography (DOT). While researchers have been developing it for more than 10 years, the method had been limited to small regions of the brain. The new DOT instrument covers two-thirds of the head and for the first time can image brain processes taking place in multiple regions and brain networks such as those involved in language processing and self-reflection (daydreaming).

“When the neuronal activity of a region in the brain increases, highly oxygenated blood flows to the parts of the brain doing more work, and we can detect that,” said senior author Joseph Culver, PhD, associate professor of radiology. “It’s roughly akin to spotting the rush of blood to someone’s cheeks when they blush.”

The technique works by detecting light transmitted through the head and capturing the dynamic changes in the colors of the brain tissue.

Although DOT technology now is used in research settings, it has the potential to be helpful in many medical scenarios as a surrogate for functional MRI, the most commonly used imaging method for mapping human brain function. Functional MRI also tracks activity in the brain via changes in blood flow.

Another common method for mapping brain function is positron emission tomography (PET), which involves radiation exposure. Because DOT technology does not use radiation, multiple scans performed over time could be used to monitor patients treated for brain injuries, developmental disorders such as autism, neurodegenerative disorders such as Parkinson’s, and other diseases.

Unlike fMRI and PET, DOT technology is designed to be portable, so it could be used at a patient’s bedside or in the operating room.

While DOT doesn’t let scientists peer very deeply into the brain, researchers can get reliable data to a depth of about one centimeter of tissue. That centimeter contains some of the brain’s most important and interesting areas with many higher brain functions represented.