title: Effects of prepulses and d-amphetamine on performance and event-related potential measures on an auditory discrimination task.
abstract: BACKGROUND
  Prepulse inhibition (PPI) of the startle reflex is a measure of sensorimotor gating, that is the processing of the startle stimulus (S2) is inhibited by the interfering processing of a closely preceding prepulse (S1). It has been demonstrated that PPI is disrupted in a variety of mental disorders and that several neurotransmitter systems, including dopamine, participate in the modulation of sensorimotor gating. Previous studies have also shown that a task-relevant S1 enhances PPI in healthy subjects but not in schizophrenic patients. These findings indicate an influence of attentional processes on sensorimotor gating and an impairment of this modulation in schizophrenia.
  
  
  OBJECTIVE
  Assuming a dopamine-mediated suppression of S1 processing as a mechanism of resource management and selective attention, which might be impaired in certain mental disorders, the present study investigated the effects of the indirect dopaminergic agonist d-amphetamine on prepulse-altered S2 discrimination and event related potentials (ERPs).
  
  
  METHODS
  Twelve healthy volunteers were tested in a double-blind, placebo-controlled experimental design. Here, S2 is the target in a difficult Go/NoGo auditory discrimination task.
  
  
  RESULTS
  Confirming our previous results, S2 processing is "accentuated" by a weak acoustic prepulse in healthy subjects, thus leading to a lower rate of errors of omission but also to more false alarms (i.e. a liberal response bias). This performance change correlated with a prepulse-induced increase in the amplitude of the P3 ERP towards non-targets ("prepulse-induced non-target positivity"; PINTP). In addition, the results of the present study show that under prepulse conditions amphetamine disrupts "S2 accentuation" associated with a dose-related reduction of the P2 component of the S1 response and a plasma level related reduction of PINTP.
  
  
  CONCLUSIONS
  These data suggest an involuntary attentional shift towards S1 processing with increasing dopamine-release similar to that observed in patients with schizophrenia or OCD. It is concluded that sensory gating alters selective attention via dopaminergic modulation.
authors.affiliation: The University of Bochum, Department for Biopsychology, Bochum, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kröner
authors.forename: U
authors.initials: U
authors.lastname: Schall
authors.forename: P B
authors.initials: PB
authors.lastname: Ward
authors.forename: G
authors.initials: G
authors.lastname: Sticht
authors.forename: M
authors.initials: M
authors.lastname: Banger
authors.forename: H T
authors.initials: HT
authors.lastname: Haffner
authors.forename: S V
authors.initials: SV
authors.lastname: Catts
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D003913:Dextroamphetamine / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects*; D004298:Dopamine / Q000502:physiology; D004311:Double-Blind Method; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D012018:Reflex; D013216:Reflex, Startle / Q000502:physiology*; D012559:Schizophrenia / Q000503:physiopathology
chemical_list: D003913:Dextroamphetamine; D004298:Dopamine