Measurements of extremely slow components of MEG activities in human subjects during memory and recognition processes

Recently magnetic-field measurements of the brain have become a useful tool to study higher brain function. The purpose of this study is to propose source models of both the memorizing process and the recognition process. The components of magnetic fields perpendicular to the surface of the head were measured by using a whole cortex type of dc SQUID with a third-derivative gradiometer. The authors observed the extremely slow components of MEG activities during both the memorizing process and the recognition process. The authors estimated the sources using two current dipoles and compared the two cases