Stimulus duration influences the dipole location shift within the auditory evoked field component N100m.

The equivalent source of the neuromagnetic auditory evoked field (AEF) component N100m shifts systematically within its latency range. In the current study, possible effects of stimulus duration on this shift were analysed. 15 subjects were stimulated monaurally with tones of different duration (50, 100, 200 ms) and AEFs were recorded successively over both hemispheres. Dipoles were calculated in 5-ms-steps from 15 ms before to 15 ms after the N100m peak maximum. A dipole location shift within the N100m latency from posterior to anterior and from superior to inferior was observed. The shift in anterior-posterior direction was found to be larger in the right compared to the left hemisphere. Stimulus duration significantly affected the degree of dipole shift in this direction. It was found to be shorter the shorter the stimulus.