Applications of a superconducting detector for measurements of the magnetic field associated with cellular currents in in vitro brain preparations

Sensors based on SQUIDs (superconducting quantum interference devices) are now increasingly being used to study the magnetic evoked field (MEF) produced by neural activity in the brain. The authors have explored possible applications of this superconducting sensor as a noninvasive tool for directly monitoring currents produced by neural activity. Results from their studies on the isolated turtle cerebellum show that it is possible to measure the MEF associated with neuronal currents in an active tissue of less than 10 mm at a distance of 6 cm or more. The MEF was directly related to intraneuronal currents in magnitude and temporal waveform. The magnetic technique seems suitable for monitoring not only rapidly varying currents, by also DC and slowly varying currents that are present during such pathophysiological events as spreading depression that is believed to underlie migraine.<>