title: Impairment of a parieto-premotor network specialized for handwriting in writer's cramp.
abstract: Handwriting with the dominant hand is a highly skilled task singularly acquired in humans. This skill is the isolated deficit in patients with writer's cramp (WC), a form of dystonia with maladaptive plasticity, acquired through intensive and repetitive motor practice. When a skill is highly trained, a motor program is created in the brain to execute the same movement kinematics regardless of the effector used for the task. The task- and effector-specific symptoms in WC suggest that a problem particularly occurs in the brain when the writing motor program is carried out by the dominant hand. In this MRI study involving 12 WC patients (with symptoms only affecting the right dominant hand during writing) and 15 age matched unaffected controls we showed that: (1) the writing program recruited the same network regardless of the effector used to write in both groups; (2) dominant handwriting recruited a segregated parieto-premotor network only in the control group; (3) local structural alteration of the premotor area, the motor component of this network, predicted functional connectivity deficits during dominant handwriting and symptom duration in the patient group. Dysfunctions and structural abnormalities of a segregated parieto-premotor network in WC patients suggest that network specialization in focal brain areas is crucial for well-learned motor skill. Hum Brain Mapp 37:4363-4375, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Human Motor Control Section, Medical Neurology Branch. NINDS, NIH 10 Center Drive, Bldg 10/7D37, Bethesda, MD, 20892 and Centre de Neuroimagerie de Recherche (CENIR), Institut du Cerveau et de la Moelle (ICM), 47-83 boulevard de l'hôpital, 75651 Paris Cedex 13, France.
authors.forename: Cecile
authors.initials: C
authors.lastname: Gallea
authors.affiliation: Human Motor Control Section, Medical Neurology Branch. NINDS, NIH 10 Center Drive, Bldg 10/7D42, Bethesda, MD, 20892.
authors.forename: Silvina G
authors.initials: SG
authors.lastname: Horovitz
authors.affiliation: Human Motor Control Section, Medical Neurology Branch. NINDS, NIH, 10 Center Drive, Bldg 10/7D42, Bethesda, MD, 20892.
authors.forename: Muslimah 'Ali
authors.initials: M'
authors.lastname: Najee-Ullah
authors.affiliation: Human Motor Control Section, Medical Neurology Branch. NINDS, NIH 10 Center Drive, Bldg 10/7D37, Bethesda, MD, 20892.
authors.forename: Mark
authors.initials: M
authors.lastname: Hallett
mesh_terms: D001931:Brain Mapping; D015331:Cohort Studies; D020821:Dystonic Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006225:Hand / Q000503:physiopathology*; D006236:Handwriting; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology*; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology*
keywords: dystonia; human; motor program; neuroimaging; task specificity