Association of the N100 TMS-evoked potential with attentional processes: A motor cortex TMS–EEG study

Abstract The most thoroughly studied transcranial magnetic stimulation(TMS)-evoked electroencephalogram (EEG) potential (TEP), N100, is often defined as a measure of cortical inhibition. We explored the association of the N100amplitude with attention in 51 young healthy adults. Navigated TMS with simultaneous EEG registering was applied over the left primary motor cortexat the intensity of 110% of the resting motor threshold. Attention was assessed with the Paced Auditory Serial Addition Test(PASAT). We found a negative Pearson correlation ( p  = .023, r  = −0.317) between the left centroparietal N100amplitude and the PASAT score. Of the participants, the 17 with the highest PASAT scores and 17 with the lowes scores were selected for further analysis, in which a significant between-group difference in the left centroparietal N100was found ( p  = .017). The topographic specificity of this finding was further confirmed with linear mixed model (LMM) analysis, in which significant differences were detected in the N100amplitude; most prominently in the left centroparietal region ( p  = .001). A smaller N100amplitude was associated with better performance in the attention task. Our findings suggest that the GABA-B-ergic TEP N100is associated with attentional processes and thus represents cortical inhibition beyond motor inhibition.