Measurement of Evoked Magnetic and Electric Fields Associated with Visual Apparent Movement.

This study focuses on the measurement and topographic analysis of evoked magnetic and electric fields associated with the perception of visual apparent movement. Evoked magnetic fields were obtained in response to about 50 trials of apparent movement stimulation in the bilateral temporal and occipital lobes. Evoked potentials were also recorded from 16 scalp sites in the 10-20 system, and used to create topographic potential maps. The magnetic fields and potential topographic maps suggest that the sources associated with visual apparent movement can be modeled by at least four current dipoles with two dipoles located in the bilateral temporal area and oriented toward the vertex, and two small dipoles located almost in the occipital area and oriented downward. This dipole model closely simulates the evoked potentials and magnetic fields associated with visual apparent movement.