title: Brain dopamine and kinematics of graphomotor functions.
abstract: Three experiments were performed in an attempt to achieve a better understanding of the effect of dopamine on handwriting. In the first experiment, kinematic aspects of handwriting movements were compared between healthy participants and patients with Parkinson's disease (PD) on their usual dopaminergic treatment and following withdrawal of dopaminergic medication. In the second experiment, the writing performance of healthy participants with a hyperechogenicity of the substantia nigra as detected by transcranial sonography (TCS) was compared with the performance of healthy participants with low echogenicity of the substantia nigra. The third experiment examined the effect of central dopamine reduction on kinematic aspects of handwriting movements in healthy adults using acute phenylalanine and tyrosine depletion (APTD). A digitising tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task. Movement time, distance, velocity, acceleration and measures of fluency of handwriting movements were measured. The kinematic analysis of handwriting movements revealed that alterations of central dopaminergic neurotransmission adversely affect movement execution during handwriting. In comparison to the automatic processing of handwriting movements displayed by control participants, participants with an altered dopaminergic neurotransmission shifted from an automatic to a controlled processing of movement execution. Central dopamine appears to be of particular importance with regard to the automatic execution of well-learned movements.
authors.affiliation: Department of Experimental Psychology, University of Regensburg, 93040 Regensburg, Germany. klaus.lange@psychologie.uni-regensburg.de
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Lange
authors.forename: Lara
authors.initials: L
authors.lastname: Mecklinger
authors.forename: Susanne
authors.initials: S
authors.lastname: Walitza
authors.forename: Georg
authors.initials: G
authors.lastname: Becker
authors.forename: Manfred
authors.initials: M
authors.lastname: Gerlach
authors.forename: Markus
authors.initials: M
authors.lastname: Naumann
authors.forename: Oliver
authors.initials: O
authors.lastname: Tucha
mesh_terms: D000328:Adult; D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D001696:Biomechanical Phenomena; D001921:Brain / Q000187:drug effects / Q000503:physiopathology*; D003196:Computer Graphics; D018592:Cross-Over Studies; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000627:therapeutic use; D004311:Double-Blind Method; D004453:Echoencephalography; D005260:Female; D006236:Handwriting; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy / Q000503:physiopathology; D010649:Phenylalanine / Q000172:deficiency; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D013378:Substantia Nigra / Q000187:drug effects / Q000503:physiopathology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014443:Tyrosine / Q000172:deficiency
chemical_list: D000978:Antiparkinson Agents; D018491:Dopamine Agonists; D014443:Tyrosine; D010649:Phenylalanine; D004298:Dopamine