title: Movement-related potentials in the Go/NoGo task: the P3 reflects both cognitive and motor inhibition.
abstract: OBJECTIVE
  The contribution of movement-related potentials (MRPs) to the Go/NoGo N2 and P3 'inhibitory' effects is controversial. This study examined these components in overt and covert response inhibition tasks.
  
  
  METHODS
  Twenty adult participants counted or button-pressed in response to frequent (60%) and rare (20%) Go stimuli in a Go/NoGo task with equiprobable rare (20%) NoGo stimuli.
  
  
  RESULTS
  The N2 NoGo effect did not differ between Count and Press responses, but the P3 NoGo effect was amplified during the Press task. Additionally, subtraction of the ERP waveform for Count NoGo from Press NoGo trials revealed a positivity between 200 and 400ms, occurring maximally over the central region, contralateral to the responding hand. This difference wave became significant at 210-260ms, close to the estimated time taken to stop an overt response.
  
  
  CONCLUSIONS
  The N2 NoGo effect may reflect a non-motoric stage of inhibition, or recognition of the need for inhibition, while the NoGo P3 may overlap with a positive MRP occurring specifically on trials where overt motor responses must be inhibited.
  
  
  CONCLUSIONS
  The study confirms that the N2 and P3 NoGo effects are not solely due to movement-related potentials, and posits the NoGo P3 as a marker of motor inhibition.
authors.affiliation: School of Psychology, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; School of Psychology and Brain & Behaviour Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia. Electronic address: janette.smith@newcastle.edu.au.
authors.forename: Janette L
authors.initials: JL
authors.lastname: Smith
authors.affiliation: School of Psychology and Brain & Behaviour Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Johnstone
authors.affiliation: School of Psychology and Brain & Behaviour Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Barry
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D003265:Contingent Negative Variation / Q000502:physiology; D004307:Dose-Response Relationship, Radiation; D004569:Electroencephalography / Q000379:methods; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009068:Movement / Q000502:physiology*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology