title: Random Number Generation and Executive Functions in Parkinson's Disease: An Event-Related Brain Potential Study.
abstract: BACKGROUND
  The generation of random sequences is considered to tax executive functions and has been reported to be impaired in Parkinson's disease (PD) previously.
  
  
  OBJECTIVE
  To assess the neurophysiological markers of random number generation in PD.
  
  
  METHODS
  Event-related potentials (ERP) were recorded in 12 PD patients and 12 age-matched normal controls (NC) while either engaging in random number generation (RNG) by pressing the number keys on a computer keyboard in a random sequence or in ordered number generation (ONG) necessitating key presses in the canonical order. Key presses were paced by an external auditory stimulus at a rate of 1 tone every 1800 ms. As a secondary task subjects had to monitor the tone-sequence for a particular target tone to which the number "0" key had to be pressed. This target tone occurred randomly and infrequently, thus creating a secondary oddball task.
  
  
  RESULTS
  Behaviorally, PD patients showed an increased tendency to count in steps of one as well as a tendency towards repetition avoidance. Electrophysiologically, the amplitude of the P3 component of the ERP to the target tone of the secondary task was reduced during RNG in PD but not in NC.
  
  
  CONCLUSIONS
  The behavioral findings indicate less random behavior in PD while the ERP findings suggest that this impairment comes about, because attentional resources are depleted in PD.
authors.affiliation: Department of Neurology, University of Lübeck, Lübeck, Germany.|Institute of Psychology II, University of Lübeck, Lübeck, Germany.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Münte
authors.affiliation: Department of Neurology, University of Lübeck, Lübeck, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Joppich
authors.affiliation: Neurologische Klinik Hessisch Oldendorf, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Däuper
authors.affiliation: Department of Neurology and Clinical Neurophysiology, Medical School of Hannover, Hannover, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schrader
authors.affiliation: Department of Neurology and Clinical Neurophysiology, Medical School of Hannover, Hannover, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Dengler
authors.affiliation: Department of Neurology, University of Lübeck, Lübeck, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Heldmann
mesh_terms: D000368:Aged; D002540:Cerebral Cortex / Q000503:physiopathology*; D004569:Electroencephalography; D005071:Evoked Potentials; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000503:physiopathology*
keywords: Parkinson’s disease; dual task; event-related potentials; random number generation