Parkinsons disease and the control of size and speed in handwriting

• Published in: Neuropsychologia Vol. 37; no. 6; pp. 685 - 694
• Main Authors: Gemmert, A.w.a.Van, Teulings, H.-L, Contreras-Vidal, J.L, Stelmach, G.e
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.06.1999; Elsevier Science
• Subjects: Aged; Aged, 80 and over; Basal ganglia; Basal Ganglia - physiology; Biological and medical sciences; Case-Control Studies; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Dopamine - physiology; Female; Finger movements; Force amplitude; Frontal Lobe - physiology; Geriatrics; Handwriting; Humans; Linear Models; Male; Medical sciences; Middle Aged; Models, Neurological; Motor control; Motor Skills - physiology; Movement Disorders - physiopathology; Neural networks; Neural Networks (Computer); Neural Pathways - physiology; Neurology; Parkinson Disease - physiopathology; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Reaction Time - physiology; Volition - physiology; Wrist movements; Force amplitude; Basal ganglia; Finger movements; Neural networks; Motor control; Wrist movements; Human; Amplitude; Nervous system diseases; Force; Finger; Parkinson disease; Manual activity; Velocity; Cerebral disorder; Wrist; Hand writing; Central nervous system disease; Body movement; Adult; Degenerative disease; Elderly; Extrapyramidal syndrome
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/S0028-3932(98)00122-5

This experiment investigated whether Parkinsons disease (PD) patients experience problems in producing stroke size, stroke duration or both, in a handwriting task. Thirteen PD patients and 15 elderly controls wrote four patterns of varying complexity on a digitizer .tablet. The participants were instructed to execute the writing movements: at a normal size and speed; as fast as possible; two times larger than normal; and two times larger and as fast as possible. PD patients had no difficulty increasing speed while maintaining size and had no difficulty increasing size while maintaining speed. However, they showed significantly smaller size increases in the two times larger condition as compared to the elderly controls. The conditions were also simulated by a neural network model of normal and PD movement control that produced a stroke pattern that approximated the experimental data. For the instructions used, the results suggest that when patients scale speed, they have no difficulty controlling force amplitude, but when they scale stroke size, they have a problem controlling force amplitude. Thus, PD patients may have reduced capability to maintain a given force level for the stroke time periods tested with the instructions.