Researchers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and the Johns Hopkins School of Medicine in Baltimore have achieved a breakthrough in noninvasive, high-resolution recording of neural brain activity. They demonstrated that neural tissue deformations may provide a novel signal for brain activity that has the potential to be leveraged for future BCI devices. The team developed a digital holographic imaging (DHI) system to identify and validate the signal as tissue deformation that occurs during neural activity. Tissue deformation is only tens of nanometers in height, so the DHI system was developed with sensitivities at the nanometer scale.
The DHI system operates by actively illuminating the tissue with a laser and recording the light scattered from the neural tissue on a special camera. This information is processed to form a complex image of the tissue from which magnitude and phase information can be precisely recorded to spatially resolve changes in brain tissue velocity. Numerous fundamental tests were conducted over several years to ensure the signal the team identified was in fact correlated to when neurons fired. The neural signal was challenging to identify because of competing noise from physiological clutter such as blood flow, heart rate and respiratory rate. They also discovered that the clutter could also provide insight into the health of an individual.
More information:
https://www.jhuapl.edu/news/news-releases/241114-noninvasive-brain-computer-interface