A five-channel magnetic detection system is requested to measure magnetic fields produced by the human brain, and other biological sources. The sensors will be five dc SQUIDs. The system will operate in either of two modes. In the first mode it will perform multi-location (ML) recording over the head (or other biological sources). It will thus record MEGs simultaneously from five locations on the head, instead of from a single location as is now done. This will allow a complete magnetoencephalogram (MEG) map (greater than 25 locations) to be recorded in one session instead of 5-10 sessions presently necessary; hence, new research and clinical studies will become feasible. In the second mode it will perform spatially high-resolution (HR) recording, but at a single location at a time. In this mode it will """"""""focus"""""""" better than does any present MEG system, and will allow spatial resolution of sources not previously possible. The two-mode operation will be accomplished by using two interchangeable sets of detection coils. For the ML mode the set will consist of five first-order, long-base gradiometers; these will measure locations 2.0 cm apart on the head in a cruciform pattern. For the HR mode the set will consist of two quadrupolar coils (each with four side-by-side loops) oriented perpendicularly to each other, allowing spatially high-resolution measurements in both tangential directions (orthogonal to each other) along the head. This system will be used in the MIT shielded room, allowing magnetic recordings of the lowest possible noise, hence MEG maps of the highest accuracy; because the only other multi-channel system in the U.S. is used in an unshielded (noisy) setting, the system requested here is unique in terms of low-noise capability. Six major users (75% of time) and two minor users (less than 25% of time) will share the equipment. The major projects are: Localizing epileptic foci in patients, clarifying evoked sources in the brain, testing the moving-dipole method for determining brain sources, characterizing relaxation and clearance in the lung, determining later somatosensory evoked sources, and measuring in vitro relaxation rates in macrophage cells. The minor (non-NIH) projects are: Measuring nerve signals in the spinal cord, and investigating a visually-evoked source in the brain's cortex.
