The first intraoperative recording of the action current of the human median nerve bundle was reported by Wikswo et al.
The net signal of the action current is nearly zero, as the phase shifts of depolarization and repolarization cancel.
In conclusion, we find that MRI measurements of action current in nerve are unlikely using current technology.
Magnetic measurement of action currents using magnetic resonance would be a significant diagnostic tool because it would allow true functional imaging of action currents using all the power and resolution of MRI.
2009) have attempted to calculate the magnetic field associated with action currents from first principles.