On the possibility of independent activation of bilateral mismatch negativity (MMN) generators

Event-related potential (ERP) studies on auditory selective attention have suggested that the neuronal traces underlying the mismatch negativity (MMN) develop separately for left and right ear inputs. We investigated whether this feature of the MMN could be exploited to activate the MMN generators in each hemisphere independently. Given the location of the MMN sources, this would allow separate assessment of left and right hemisphere auditory cortical structures. The MMN was elicited in a dichotic oddball paradigm using stimuli and conditions of stimulation that should optimize transmission of left and right ear stimuli to the contralateral auditory cortices. The MMN demonstrated no interhemispheric asymmetries, indicating that the bilateral MMN generators were symmetrically involved. The results of a supplementary experiment provide evidence for the simultaneous existence of multiple traces for MMN generation.