title: Dopaminergic treatment modulates sensory attenuation at the onset of the movement in Parkinson's disease: A test of a new framework for bradykinesia.
abstract: BACKGROUND
  The primary motor sign of Parkinson's disease is bradykinesia. It has been surprisingly difficult to provide a clear neurobiological mechanism for this fundamental movement deficit in Parkinson's disease. It has been proposed that in healthy individuals the gating of sensory afferents prior to and during movement is an essential step in initiating movement. This down-weighting has been proposed to account for the attenuation of the somatosensory evoked potential following median nerve stimulation at the onset of and during hand movements. The objective of this study was to test whether this sensory attenuation present at movement onset in healthy controls is present in patients with Parkinson's disease.
  
  
  METHODS
  Eighteen right-handed patients with idiopathic Parkinson's disease and 16 right-handed age-matched healthy participants were studied. Somatosensory evoked potentials were elicited after electrical stimulation of the median nerve at the wrist. Electroencephalograms were recorded over the scalp at 3 sites on according to the International 10-20 System (F3, C3, and P3). Somatosensory evoked potentials were recorded in 2 conditions: at rest and at the onset of movement (a self-paced abduction movement of the right thumb).
  
  
  RESULTS
  Off medication, Parkinson's disease patients had no sensory attenuation at movement onset. On medication, sensory attenuation at movement onset was present.
  
  
  CONCLUSIONS
  We suggest that this preliminary result is consistent with the hypothesis that, a failure in sensory attenuation contributes to the difficulties in movement initiation in Parkinson's disease.
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.|Department of Basic Medical Sciences, Neuroscience and Sense Organs, Aldo Moro University, Bari, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Macerollo
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.|Neuroscience Laboratory, Department of Neurology, China Medical University Hospital, Taichung, Taiwan.|School of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Jui-Cheng
authors.initials: JC
authors.lastname: Chen
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
authors.forename: Prasad
authors.initials: P
authors.lastname: Korlipara
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
authors.forename: Thomas
authors.initials: T
authors.lastname: Foltynie
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Rothwell
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
authors.forename: Mark John
authors.initials: MJ
authors.lastname: Edwards
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
authors.forename: James Morvan
authors.initials: JM
authors.lastname: Kilner
mesh_terms: D000368:Aged; D015259:Dopamine Agents / Q000627:therapeutic use*; D004558:Electric Stimulation; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects*; D005260:Female; D006801:Humans; D018476:Hypokinesia / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects / Q000502:physiology; D010300:Parkinson Disease / Q000188:drug therapy*; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D014953:Wrist / Q000294:innervation
chemical_list: D015259:Dopamine Agents
keywords: Parkinson's disease; bradykinesia; sensory attenuation; sensory system