Controlling technology with just your mind may have once been the realm of science fiction, but advances in brain-computer interface (BCI) technology have brought it much closer to reality. Researchers at the Johns Hopkins Applied Physics Laboratory (APL) and the Johns Hopkins School of Medicine have made a groundbreaking discovery in noninvasive, high-resolution brain activity recording. In a recent paper published in Scientific Reports, the team revealed that neural tissue deformations could provide a novel signal for brain activity, one that could revolutionize future BCI devices.
Unlike current BCI technologies, which often require invasive surgical implants to record and interpret neural signals, this new approach offers a noninvasive alternative with the potential for broader applications. “Today, the highest impact BCI technologies require invasive surgical implants to record and decode brain activity,” explained Mike Wolmetz, program manager for Human and Machine Intelligence at APL. “Our findings present the foundations for a new approach that could significantly expand the possibilities for nonsurgical BCI.”
Brain-computer interfaces work by recording neural activity associated with specific functions—such as speech, movement, or attention—and using that information to control external devices, often without physical movement. However, current noninvasive methods have been limited by issues like low spatial resolution and interference from physiological noise. As of now, only a small number of people have undergone BCI implant procedures, making it a clinical tool with limited accessibility.
To address these limitations, the team at Johns Hopkins developed a digital holographic imaging (DHI) system to identify and record tissue deformations that occur during neural activity. These deformations, which are on the scale of just tens of nanometers, can now be detected with extraordinary precision. The DHI system uses laser illumination and specialized cameras to gather complex data on neural tissue, enabling researchers to observe minute changes in brain tissue velocity linked to neuronal firing.
Despite the challenge of isolating neural signals from physiological clutter—such as blood flow and heart rate—the team was able to develop a method to detect the neural activity through the scalp and skull. “This was a remote sensing problem,” said David Blodgett, the principal investigator for the project. “We had to detect a very small neural signal in a complex and noisy environment—the brain.”
In addition to overcoming this technical hurdle, the team made an unexpected discovery. The physiological signals, once considered noise, also provided valuable insight into brain health. For example, the DHI system demonstrated the ability to noninvasively measure intracranial pressure, an important clinical indicator traditionally measured through invasive methods like drilling a hole in the skull. This capability could be a game-changer for monitoring brain health, especially in patients with traumatic brain injuries or those receiving critical care.
“Being able to monitor brain function and health through the skull without invasive surgeries is very clinically useful,” said Austen Lefebvre, an assistant professor of neurology at Johns Hopkins University and co-author of the study.
While the system is still in its early stages, the team’s findings open the door to new ways of monitoring brain function and health, both for clinical and research applications. With further refinement, digital holographic imaging could play a key role in noninvasive BCI systems that allow for more accurate and accessible mind-controlled technologies.
“The priority now is to demonstrate the potential for basic and clinical neuroscience application in humans,” said Wolmetz, underscoring the transformative potential of this research. As the field advances, it could unlock new possibilities for controlling machines and monitoring brain health without the need for invasive surgery.
By Impact Lab
