Magnetic field influence on central nervous system function.

The effects of strong static magnetic fields on the excitability of striate cortex in adult cats was studied. The visual evoked response was used as a measure of cortical excitability. In all animals a 1200-G field was associated with a significant decrease in both amplitude and variability of the evoked response. This effect began more than 50 s after the field was turned on and persisted, even after the field was turned off, for several minutes. This phenomenon appears to be due to action of the magnetic field at the synapse rather than on axonal conduction.