ABSTRACT
This chapter provides an overview of neuromagnetism, which is defined as the study of magnetic fields associated with the electrical activity of neurons. Like the other chapters in this volume, this chapter especially emphasizes the magnetic fields generated by the human brain. In view of this emphasis, we introduce the reader to magnetoencephalography, a technique that measures the external magnetic field, near the scalp, of the intact human brain. This general overview is designed to help newcomers appreciate the more technical chapters. It provides a relatively nontechnical description of the physical basis of the neuromagnetic field, the different methods used to detect it, and how the magnetoencephalogram complements the electroencephalogram. We explain how analysis of MEG data can yield high temporal and reasonable spatial resolution “representations” of current distributions on the cerebral cortex. These magnetic source images complement the other functional imaging modalities. Furthermore, we describe some typical uses of magnetic source imaging in medicine and in cognitive neural science. Finally we briefly discuss complementary modes of functional brain imaging; such as positron emission tomography and functional magnetic resonance imaging, as well as recent attempts to combine multiple imaging modalities to achieve high spatiotemporal resolution functional images of the human brain.
