Figure 6

Equivalent circuit model of a typical neuron cell body, drawn here as a cube, in a potential gradient field. R_ECF is the extracellular fluid resistance. R_ICF is the intracellular resistance. Insulating up-field and down-field cell membranes act as series capacitors, C. Half the total voltage difference across the cell appears across each membrane. In magnetic stimulation a voltage gradient on the order of 10 microvolts/micrometer × 20 micrometers or 2 mV appears across the cell. One side of the cell is depolarized and the other side is hyperpolarized by half this amount or 1 mV, which is insufficient to stimulate the cell.