Comparison between simultaneously recorded auditory-evoked magnetic fields and potentials elicited by ipsilateral, contralateral and binaural tone burst stimulation.

Both auditory-evoked magnetic fields (AEMF) and auditory-evoked potentials (AEP) mainly consist of three peaks with latencies of about 50, 100 and 160 ms. Comparison of responses to ipsilateral, contralateral and binaural stimulation yields no significant amplitude or latency differences of the AEP peaks whereas the simultaneously recorded AEMF peaks exhibit a 10 ms shorter latency and an approximately 38% greater amplitude for contralateral versus ipsilateral stimulation. This fact can be due to differences in the strength, location (especially the depth) and the direction of the dipole source, and a decision cannot be made considering the data recorded from just one position. Another finding is that binaural stimulation reduces the peak amplitudes by approximately 25% compared with contralateral stimulation. This result indicates some kind of interference between the ipsilateral and contralateral pathways ('binaural interaction').