Discrete and dynamic scaling of the size of continuous graphic movements of parkinsonian patients and elderly controls (original) (raw)
Related papers
2001
Research suggests that Parkinson's Disease (PD) patients have difficulty scaling the magnitude of their movements. Longstaff et al (2001) showed that patients could continuously scale a drawing movement (spiral) up to a diameter of 5cm like elderly controls, but their trajectories were more variable and there was a smaller distance between each revolution. The present study tests the ability of patients and controls to perform a continuous drawing task with discrete scaling. Subjects were 11 idiopathic PD patients (ages 55 to 81; 8 male, 3 female; Hoehn & Yahr stages 2 and 3; off medication) and 13 elderly controls (ages 62 to 81; 5 male, 6 female). Subjects drew circles on a digitizer matching the size of target circles of diameter 1, 1.5, 2, 3 and 5cm. Five revolutions of each were drawn in the conditions accurate and fast and accurate. Both groups drew circles a similar size, increasing with target size but undershooting the larger circles. Circle size did not change with co...
Spatial features of angular drawing movements in Parkinson’s disease patients
Acta Psychologica, 1998
The present study shows that drawings from ParkinsonÕs disease (PD) patients display speci®c spatial features when compared to those produced by age-matched controls. Their drawings are globally smaller, or more precisely, the larger the requested size, the greater the size reduction. PD subjects have also more diculties in producing obtuse than acute angles: angles of obtuse patterns are shrinking and their segment lengths are shortened. This could be due to the fact that an obtuse angle brings the eector joints close to the limits of their functional ranges of motion, which may be reduced in PD patients. Results related to segment direction show that PD patients are globally more imprecise than controls in the production of movement directions, but perform nevertheless relatively well for horizontals and verticals drawn in preferred directions. These results are referred to two contradictory models relating movement direction to the type of movement coordination involved. Ó 1998 Elsevier Science B.V. All rights reserved.
Parkinsons disease and the control of size and speed in handwriting
Neuropsychologia, 1999
This experiment investigated whether Parkinson|s disease "PD# patients experience problems in producing stroke size\ stroke duration or both\ in a handwriting task[ Thirteen PD patients and 04 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 possiblet wo times larger than normal^and two times larger and as fast as possible[ PD patients had no di.culty increasing speed while maintaining size and had no di.culty increasing size while maintaining speed[ However\ they showed signi_cantly 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 di.culty 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[ Þ 0888 Elsevier Science Ltd[ All rights reserved[ Keywords] Force amplitude^Neural networks^Basal ganglia^Motor control^Wrist movements^Finger movements Corresponding author[ Tel[] ¦0 591 854 3607^fax] ¦0 591 854 7097^e!mail] vangemmertÝasu[edu
International Journal of Rehabilitation Research, 2009
Variances of drawing arm movements between patients with Parkinson's disease and healthy controls were compared. The aim was to determine whether differences in joint synergies or individual joint rotations affect the endpoint (hand position) variance. Joint and endpoint coordinates were measured while participants performed drawing tasks. Variances of arm configurations and endpoints were computed and statistically analyzed for 12 patients and 12 controls. The variance of arm movements for patients (both for arm configuration and endpoint) was overall higher than that for the control group. Variation was smaller for drawing a circle versus a square and for drawing with the dominant versus the nondominant hand within both groups. The ratio of arm configuration variances between groups was similar to the ratio of endpoint variances. There were significant differences in the velocity, but not in the path lengths of movements comparing the two groups. Patients presented less movement stability while drawing different figures in different trials. Moreover, the similarity of the ratios suggests that the ill-coordinated hand movement was caused by the error in the movements of individual body parts rather than by the lack of intersegmental coordination. Thus, rehabilitation may focus on the improvement of the precision of individual joint rotations.
Control of stroke size, peak acceleration, and stroke duration in Parkinsonian handwriting
Human Movement Science, 1991
This experiment investigates movement coordination in Parkinson's disease (PD) subjects. Seventeen PD patients and 12 elderly control subjects performed several handwriting-like tasks on a digitizing writing tablet resting on top of a table in front of the subject. The writing patterns, in increasing order of coordination complexity, were repetitive back-and-forth movements in various orientations, circles and loops in clockwise and counterclockwise directions, and a complex writing pattern. The patterns were analyzed in terms of jerk normalized for duration and size per stroke. In the PD subjects, back-and-forth strokes, involving coordination of fingers and wrist, showed larger normalized jerk than strokes performed using either the wrist or the fingers alone. In the PD patients, wrist flexion (plus radial deviation) showed greater normalized jerk in comparison to wrist extension (plus ulnar deviation). The elderly control subjects showed no such effects as a function of coordination complexity. For both PD and elderly control subjects, looping patterns consisting of circles with a left-to-right forearm movement, did not show a systematic increase of normalized jerk. The same handwriting patterns were then simulated using a biologically inspired neural network model of the basal ganglia thalamocortical relations for a control and a mild PD subject. The network simulation was consistent with the observed experimental results, providing additional support that a reduced capability to coordinate wrist and finger movements may be caused by suboptimal functioning of the basal ganglia in PD. The results suggest that in PD patients fine motor control problems may be caused by a reduced capability to coordinate the fingers and wrist and by reduced control of wrist flexion. r 1997
Hypometria and bradykinesia during drawing movements in individuals with Parkinson’s disease
Experimental Brain Research, 2009
To address the hypothesis that Parkinson's disease (PD) patients have deWcits in controlling acceleration, a drawing task was used in which target size, frequency, and weight of pen were manipulated. In accordance with previous results, it was found that, relative to controls, PD patients produced movements at the required frequency, but moved signiWcantly slower, produced less acceleration, and drew smaller-than-required stroke sizes. This resulted in smaller-than-required movement amplitudes, suggesting that hypometria and bradykinesia in drawing and/or handwriting are related. Patients were found to perform similarly to controls when the target size was 1 cm. However, their performance became more dissimilar at greater stroke lengths. In addition to the aforementioned eVects it was found that movement amplitude error was less when the pen was 20 times heavier than the normal pen and that the increased load may dampen abnormal limb-stiVness characteristics induced by PD.
Parkinsonian Patients Reduce Their Stroke Size with Increased Processing Demands
Brain and Cognition, 2001
Parkinson's disease (PD) patients often show reductions in writing size (micrographia) as the length of the text they produce increases. The cause for these reductions in stroke size are not well understood. Reductions in stroke size could be associated with either concurrent processing demands that result from the coordination and control of fingers, wrist, and arm during writing and the processing of future words or increased extension of the wrist joint as the execution of the writing progresses to the right across the page, resulting in increased stiffness in the pen-limb system. Parkinson's patients and elderly controls wrote phrases of different lengths with target patterns in various serial positions. When the number of words to be written increased, PD patients reduced their stroke size of the initial target pattern, while the elderly controls did not reduce their stroke size. There was no systematic change in stroke size of the second pattern as function of serial position. This result suggests that PD patients reduce the size of their handwriting strokes when concurrent processing load increases. © 2001 Elsevier Science
Experimental Brain Research, 2009
An experiment was conducted to contrast the motor performance of three groups (N = 20) of participants: (1) patients with confirmed Parkinson Disease (PD) diagnose; (2) age-matched controls; (3) young adults. The task consisted of scribbling freely for 10 s within circular frames of different sizes. Comparison among groups focused on the relation between the figural elements of the trace (overall size and trace length) and the velocity of the drawing movements. Results were analysed within the framework of previous work on normal individuals showing that instantaneous velocity of drawing movements depends jointly on trace curvature (Two-thirds Power Law) and trace extent (Isochrony principle). The motor behaviour of PD patients exhibited all classical symptoms of the disease (reduced average velocity, reduced fluency, micrographia). At a coarse level of analysis both isochrony and the dependence of velocity on curvature, which are supposed to reflect cortical mechanisms, were spared in PD patients. Instead, significant differences with respects to the control groups emerged from an in-depth analysis of the velocity control suggesting that patients did not scale average velocity as effectively as controls. We factored out velocity control by distinguishing the influence of the broad context in which movement is planned—i.e. the size of the limiting frames—from the influence of the local context—i.e. the linear extent of the unit of motor action being executed. The balance between the two factors was found to be distinctively different in PD patients and controls. This difference is discussed in the light of current theorizing on the role of cortical and sub-cortical mechanisms in the aetiology of PD. We argue that the results are congruent with the notion that cortical mechanisms are responsible for generating a parametric template of the desired movement and the BG specify the actual spatio-temporal parameters through a multiplicative gain factor acting on both size and velocity