Auditory MEG mismatch responses modified by visual stimulation accompanying auditory stimulation

Abstract

We investigated the effects of visual stimulation on auditory mismatch responses using a magnetoencephalography (MEG) system. Mismatch magnetic fields (MMNms, equivalents of EEG mismatch negativity, MMN) were recorded in 10 healthy subjects under three audio-visual conditions, which consisted of auditory stimulation with a static visual stimulation (A-0), auditory + synchronous visual stimulation (AV-S), and auditory + asynchronous visual stimulation (AV-R). Clear MMNms were obtained from eight subjects. The amplitude of the root mean square (r.m.s.) value, as well as the global field power, under AV-S conditions were greater compared to those recorded under other conditions in the right hemisphere (P = 0.0087, ANOVA). The latency difference of the N1ms, equivalents of the N1 ERP component recorded in the right hemisphere 100 msec after stimulation and elicited by standard and deviant stimuli, was significantly smaller under AV-S conditions than under other conditions (P = 0.016). There was no difference in the dipole localization for MMNm among the conditions. The results indicate that simultaneous visual stimulation enhances auditory MMNm. The mismatch response can be determined not only by the physical amount of deviated stimulation but also by a deviated feature produced due to accompanying stimulation of a different modality.