ABSTRACT
The advent of superconducting magnetometers in the 1960s enabled for the first time the practical detection of the minute magnetic fields produced by the natural functioning of the human brain and neurologic system. In this chapter we review the evolution of the first primitive magnetometers into the practical whole-head recording systems available today. Sam Williamson, a pioneer in this science, urged commercial developers of these systems to strive for the maximum sensitivity that the superconducting quantum interference device would allow and to never “hardwire” in sensitivity reductions. This impetus led 4-D Neuroimaging to focus its development on the use of magnetometer-style signal coils that met Williamson's standard. Starting with basic physics arguments, continuing with implementation techniques, and concluding with sam-ples of actual data, we present the case for the use of these signal coils (as opposed to gradiometers).
