Hemispheric differences in frequency dependent dipole orientation of the human auditory evoked field component N100m

Auditory evoked fields (AEF) of 19 healthy male subjects were recorded bila terally with a Philips 31-channel biomagnetometer, using two conditions of stimulation (1000 vs. 5000 Hz tones). The N100m latency was characterized b y a single moving dipole for each condition and hemisphere using a boundary element model (BEM) as volume conductor. While the right hemispheric dipol e orientations and locations did not change with respect to condition, the left hemispheric dipoles differed significantly between the 1000 and 5000 H z tones, especially in dipole orientation. The left hemispheric dipoles wer e orientated on average 10.8 degrees more vertically for the 5000 Hz condit ion. This result points to interhemispheric differences on the level of sen sory processing. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved .