Magnetic fields produced by eye blinking.

Magnetic signals produced by voluntary eye blinking were recorded. The maximal signals were found over the posterior parts of the orbits. The polarity of the signal reversed over each eye and in the frontal midline. The amplitude increases with light and amplitude decreases with darkness were similar in the electrical and magnetic blink and eye movement signals. Three different simulation models were used in the interpretation of the results. It is concluded that the primary current source of the blink signal is the transretinal current density. Lid movements change the geometry of the volume conductor resulting in changes in the measured electrical and magnetic field patterns.