[en] Repetitive transcranial magnetic stimulation (rTMS) is considered a powerful method for the study of the relationships between cortical activity and-cognitive processes. Previous ERPs studies' that focused on P300 response have shown that inhibitory/excitatory effects on prefrontal cortex (PFC), induced by low- and high-frequency rTMS, were able to modulate controlled but not automatic information processing. The present study assessed the impact of inhibition over left and right PFC induced by rTMS on mismatch negativity (MMN), which is known to represent automatic cerebral processes for detecting change. Auditory MMN was recorded in 20 subjects before and after application of left and right PFC 1-Hz rTMS for 15 min. MMN was also recorded before and after a sham-occipital 1-Hz rTMS as control condition. Results showed that 1-Hz rTMS induced no modification to either MMN latency or amplitude. In addition, N100 and P200 components to the frequent tones were not affected by rTMS. These results are consistent with previous findings showing that rTMS; over both PFC is unable to disrupt automatic information processing. However, since two sites were stimulated in the present-study, no definite conclusions about the inability of rTMS to disrupt automatic processing can be made.
Centre de Neurosciences Comportementale et Cognitive