title: N100 as a generic cortical electrophysiological marker based on decomposition of TMS-evoked potentials across five anatomic locations.
abstract: N100, the negative peak of electrical response occurring around 100 ms, is present in diverse functional paradigms including auditory, visual, somatic, behavioral and cognitive tasks. We hypothesized that the presence of the N100 across different paradigms may be indicative of a more general property of the cerebral cortex regardless of functional or anatomic specificity. To test this hypothesis, we combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to measure cortical excitability by TMS across cortical regions without relying on specific sensory, cognitive or behavioral modalities. The five stimulated regions included left prefrontal, left motor, left primary auditory cortices, the vertex and posterior cerebellum with stimulations performed using supra- and subthreshold intensities. EEG responses produced by TMS stimulation at the five locations all generated N100s that peaked at the vertex. The amplitudes of the N100s elicited by these five diverse cortical origins were statistically not significantly different (all uncorrected p > 0.05). No other EEG response components were found to have this global property of N100. Our findings suggest that anatomy- and modality-specific interpretation of N100 should be carefully evaluated, and N100 by TMS may be used as a biomarker for evaluating local versus general cortical properties across the brain.
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA. xdu@mprc.umaryland.edu.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Du
authors.affiliation: Department of Electrical Engineering and Computer Science, University of Maryland Baltimore County, Baltimore, MD, 21250, USA.
authors.forename: Fow-Sen
authors.initials: FS
authors.lastname: Choa
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Summerfelt
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Rowland
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Chiappelli
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Kochunov
authors.affiliation: Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA.
authors.forename: L Elliot
authors.initials: LE
authors.lastname: Hong
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003664:Decompression; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Cerebellum; Electroencephalography; Motor cortex; N100; Prefrontal cortex; Transcranial magnetic stimulation