title: Finger dexterity deficits in Parkinson's disease and somatosensory cortical dysfunction.
abstract: BACKGROUND
  The patho-physiological basis for finger dexterity deficits in Parkinson's disease (PD) is controversial. Previously, bradykinesia was regarded as the major mechanism. However, recent research suggested limb-kinetic apraxia as an important component of impaired fine motor skills in PD. In contrast to bradykinesia, limb-kinetic apraxia only marginally responds to dopaminergic treatment. Here we investigate the novel hypothesis that the dexterity deficits are related to an intrinsic dysfunction of primary somatosensory cortex (S1), which is not reversible by dopaminergic medication.
  
  
  METHODS
  Applying a standard and approved dexterity task (coin rotation), brain activation networks were investigated using functional magnetic resonance imaging in PD patients both ON and OFF medication and matched healthy controls.
  
  
  RESULTS
  PD patients both ON and OFF medication showed impaired S1 activation relative to controls (p < 0.05; region of interest based analysis). The impaired S1 activation remained unchanged by dopaminergic medication. Despite the considerable clinical deficit, no other brain area showed impaired activation. In contrast, structures of the basal ganglia--motor cortex loop responded to dopaminergic medication. Behaviorally, dexterity performance both ON and OFF was significantly (p < 0.05) reduced relative to controls.
  
  
  CONCLUSIONS
  Our results provide first evidence that dexterity deficits in PD are related to an S1 dysfunction which is insensitive to dopaminergic treatment.
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: thomas.foki@meduniwien.ac.at.
authors.forename: Thomas
authors.initials: T
authors.lastname: Foki
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: walter.pirker@meduniwien.ac.at.
authors.forename: Walter
authors.initials: W
authors.lastname: Pirker
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: alexander.geissler@meduniwien.ac.at.
authors.forename: Alexander
authors.initials: A
authors.lastname: Geißler
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: dietrich.haubenberger@meduniwien.ac.at.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Haubenberger
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: hilbert.fmri@gmail.com.
authors.forename: Markus
authors.initials: M
authors.lastname: Hilbert
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: ilse.hoellinger@gmail.com.
authors.forename: Ilse
authors.initials: I
authors.lastname: Hoellinger
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: mwurnig@gmail.com.
authors.forename: Moritz
authors.initials: M
authors.lastname: Wurnig
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: jakob.rath@meduniwien.ac.at.
authors.forename: Jakob
authors.initials: J
authors.lastname: Rath
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: johann.lehrner@meduniwien.ac.at.
authors.forename: Johann
authors.initials: J
authors.lastname: Lehrner
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: eva.matt@meduniwien.ac.at.
authors.forename: Eva
authors.initials: E
authors.lastname: Matt
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: florian.fischmeister@meduniwien.ac.at.
authors.forename: Florian
authors.initials: F
authors.lastname: Fischmeister
authors.affiliation: MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: siegfried.trattnig@meduniwien.ac.at.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: eduard.auff@meduniwien.ac.at.
authors.forename: Eduard
authors.initials: E
authors.lastname: Auff
authors.affiliation: Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria; MR Center of Excellence, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address: roland.beisteiner@meduniwien.ac.at.
authors.forename: Roland
authors.initials: R
authors.lastname: Beisteiner
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D005260:Female; D005385:Fingers / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010147:Pain Measurement; D010300:Parkinson Disease / Q000150:complications* / Q000473:pathology*; D011596:Psychomotor Disorders / Q000209:etiology*; D013003:Somatosensory Cortex / Q000098:blood supply / Q000503:physiopathology*
chemical_list: D010100:Oxygen
keywords: Coin rotation; Dexterity; Functional magnetic resonance imaging; Limb-kinetic apraxia; Parkinson's disease; Somatosensory cortex