title: Motor cortical inhibition in ADHD: modulation of the transcranial magnetic stimulation-evoked N100 in a response control task.
abstract: The N100 component, evoked by transcranial magnetic stimulation (TMS) and electroencephalography is associated with the activation of inhibitory cortical circuits and has recently been suggested as a potential marker of inhibition in attention-deficit/hyperactivity disorder (ADHD). The aim of the present ADHD study was to investigate the modulation of the TMS-N100 in go and nogo trials of a response control task considering stages of response preparation, activation, execution and inhibition. Eighteen children with ADHD and 19 typically developing children, aged 10-14 years, were assessed. TMS was delivered over the left motor cortex, the TMS-N100 was measured at electrode P3. The TMS-N100 was determined at rest and at different time points (50 ms before S2; 150, 300 and 500 ms after S2) in a cued go/nogo task (S1-S2 paradigm). Correlations between the TMS-N100 measures, MEP-related TMS measures (e.g., short-interval intracortical inhibition) and performance measures were calculated. At rest, the amplitude of TMS-N100 was not found to be significantly reduced in the ADHD group. During the go/nogo task, children with ADHD showed a smaller increase of TMS-N100 amplitude in go trials and a smaller decrease after inhibiting a response. In go trials, a lower TMS-N100 was associated with a smaller variability of reaction times. A smaller TMS-N100 modulation extends the picture of cortical inhibition deficits in ADHD. Findings suggest a functional involvement of the mechanisms underlying the TMS-N100 at the motor output stage.
authors.affiliation: Unit of Child Neurology and Psychiatry, Department of Neuroscience, University of Rome "Tor Vergata", Viale Oxford 81, 00133, Rome, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: D'Agati
authors.forename: Thomas
authors.initials: T
authors.lastname: Hoegl
authors.forename: Gabriel
authors.initials: G
authors.lastname: Dippel
authors.forename: Paolo
authors.initials: P
authors.lastname: Curatolo
authors.forename: Stephan
authors.initials: S
authors.lastname: Bender
authors.forename: Oliver
authors.initials: O
authors.lastname: Kratz
authors.forename: Gunther H
authors.initials: GH
authors.lastname: Moll
authors.forename: Hartmut
authors.initials: H
authors.lastname: Heinrich
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000704:Analysis of Variance; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology; D002648:Child; D003657:Decision Making; D004569:Electroencephalography; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation