HMC Physics Colloquium
Tuesdays at 16:30 in Shanahan Center for Teaching and Learning, Room B460
Robert H. Kraus, Jr.
Los Alamos National Laboratory
Imaging Human Brain Function, or, Can We “Read Your Thoughts?”
March 6, 2007
A variety of techniques have been developed to noninvasively image human brain function that are central to understanding how the brain works and to detect pathology. Current methods can be broadly divided into those that rely on hemodynamic responses as indicators of neural activity and methods that measure neural activity directly. All of the functional brain imaging approaches in use today suffer from poor temporal resolution, poor spatial localization, or not providing a direct measure of neural activity. I will focus my discussion on the physics and engineering challenges behind an improved instrument we have developed at Los Alamos for magnetoencephalography (MEG) and present some results. I will then present the physical basis and experimental evidence for a new technique to tomographically image the direct consequences of neural activity. It has been suggested that the NMR phase will be altered by neural activity and imaged by MRI methods. Demonstrating this effect has been elusive, but we propose that ultra-low field MRI may be more sensitive for measuring this effect. Yet more compelling is our hypothesis that resonant mechanisms at ultra-low fields would significantly enhance the effect of neural activity on NMR signals. The observed resonant interactions reported here can form the foundation of a new functional neuroimaging modality capable of high resolution direct neural activity and brain anatomy tomography.