Evaluating the Acute Contributions of Dopaminergic Replacement to Gait With Obstacles in Parkinson's Disease

The influence of dopaminergic replacement (DR) on gait in people with Parkinson's disease (PD) is well documented. However, little is known about the acute effects of dopamine on more complex locomotor tasks that require visual guidance to avoid obstacles during gait. The authors investigated the influence of DR on locomotor behavior in a task where movement planning and control might be challenged by the height of the obstacle. The PD group included patients diagnosed with idiopathic PD (n = 12), as well as healthy controls (n = 12). Patients walked and stepped over obstacles of different heights before (OFF) and after (ON) levodopa intake. Spatial adjustments were not modulated by DR, but the step time to perform these anticipatory gait adjustments was longer only in PD-OFF (compared with healthy controls) when approaching the highest obstacle, but not PD-ON. During the crossing phase, trail limb toe clearance of PD patients was shorter than healthy controls only during the OFF state. ON-OFF comparisons were significantly different only for the time to reach the lead foot clearance over the highest obstacle. In summary, DR partially improved movement slowness but did not directly affect movement amplitude of lower limb regulation in this gait task.     

An exploratory study of the kinematics of girls with Turner Syndrome in a visuo‐motor task

In this paper a study is reported in which a group of children with Turner Syndrome (TS) is compared on motor performance tests and real‐time kinematic data with a control group. The objective of this study was to identify possible kinematic variables that characterize the movement patterns utilized by this group of children in achieving their optimal performance. The underlying idea is that by comparing test results and movement kinematics one might gain more insight into the movement production of children than by just looking at the test results or by just using clinical movement observation. The children performed a pen and paper task, the flower trail (one of the sub‐tests of the Movement ABC) (Henderson and Sugden, 1992), on an XY‐tablet. We explored kinematic variables, such as trajectory length, movement time, velocity and pen pressure. It was found that, although girls with TS have a severe motor deficit, they are able to draw a line accurately between two narrow boundaries just as well as the control children (no significant difference in mean number of spatial errors). However, quantitative analysis revealed that girls with TS made a large amount of deviations from the optimal path such that their trajectory length increased with more than 10% per flower trail compared to the control group children. They also made more pen lifts and more changes in velocity. The study showed that children from the two groups may reach the same basic accuracy performance level by using very different strategies. Kinematic registration of fine motor tasks holds promise in gaining more insight into how clinical groups cope with their specific motor problems. Copyright © 2003 John Wiley & Sons, Ltd.     

Spiral drawing performance as an indicator of fine motor function in people with multiple sclerosis

This study investigated spiral drawing performance as an indicator of fine motor function, as well as to gain insight into adaptive movement strategies used by people with multiple sclerosis (MS). Seven people with MS, nine younger controls (mean age of 20) and eight older controls (mean age of 40) drew spirals on a graphics tablet at a comfortable speed and size. Spirography (i.e., a subjective visual assessment of the static trace) revealed indications of reduced control of the pen for people with MS. Analysis of the movements showed that people with MS tended to draw the spirals slower and with less pen pressure than controls. All groups increased their speed and pressure along with spiral size, but this increase was much steeper for the controls. MS participants drew spirals with more variability around an ideal trajectory, highlighting fine motor control degradation. MS patients tended to use a smaller scaling ratio, resulting in smaller spirals for a given number of revolutions. The younger and older control groups drew the spirals in a similar manner, and age was not a significant factor in any of the analyses. It is argued that the relatively lower pressure used, and slower, smaller movements (particularly during the more difficult outer sections of the spiral) are in part an adaptive strategy used to reduce movement variability. These results demonstrate the utility of the analysis of spiral movements as an objective technique for assessing motor control degradation, which can compliment the subjective rating based on the static pen trace. As such, it can provide further insight into the biomechanical strategies used when performing fine movements.     

The short-term effects of a hostility-reduction intervention on male coronary heart disease patients.

This preliminary study examined the effects of a hostility-reduction intervention on patients with coronary heart disease (CHD). Twenty-two high-hostile CHD men were matched on age and hostility and then randomly assigned to a hostility intervention (N = 10) or an information-control group (N = 12). Patients were reassessed immediately and 2 months posttreatment on hostility (with self-report and structured interview) and resting blood pressure. The intervention's overall effect size was moderately strong (d' = .62). Intervention patients reported at both reassessments and were observed at follow-up to be less hostile than controls. At follow-up, intervention patients had significantly lower diastolic blood pressure (DBP) than controls. Finally, reductions in hostility were significantly and positively correlated with reductions in DBP. Replication with a larger sample and CHD outcomes is recommended.     

Motor deficits in Parkinsonian reaching: dopa-sensitivity influenced by real-world task constraint

Parkinson's disease (PD) patients can perform many daily activities, but movement deficits are evident. Those deficits may be increased when the required movement is constrained in accuracy. Variable improvements in performance with PD medication have been demonstrated, and sensitivity to task constraint has been evident in some studies. The authors quantified both specific movement deficits and improvements for PD patients in a reaching task. PD patients (N=8) both on and off medication showed a need for greater ongoing control in movements with higher task-accuracy constraints. Increased task-accuracy constraints further compromised movement timing and structure among PD patients who were off medication, suggesting that unmedicated PD patients may typically compensate by using more conscious control of movement, resulting in increased slowing and segmentation of components when higher task accuracy is required.     

Parkinson's disease differentially affects adaptation to gradual as compared to sudden visuomotor distortions

Patients with Parkinson’s disease (PD) have difficulties in movement adaptation to optimize performance in novel environmental contexts such as altered screen cursor-hand relationships. Prior studies have shown that the time course of the distortion differentially affects visuomotor adaptation to screen cursor rotations, suggesting separate mechanisms for gradual and sudden adaptation. Moreover, studies in human and non-human primates suggest that adaptation to sudden kinematic distortions may engage the basal ganglia, whereas adaptation to gradual kinematic distortions involves cerebellar structures. In the present studies, participants were patients with PD, who performed center-out pointing movements, using either a digitizer tablet and pen or a computer trackball, under normal or rotated screen cursor feedback conditions. The initial study tested patients with PD using a cross-over experimental design for adaptation to gradual as compared with sudden rotated hand-screen cursor relationships and revealed significant after-effects for the gradual adaptation task only. Consistent with these results, findings from a follow-up experiment using a trackball that required only small finger movements showed that patients with PD adapt better to gradual as against sudden perturbations, when compared to age-matched healthy controls. We conclude that Parkinson’s disease affects adaptation to sudden visuomotor distortions but spares adaptation to gradual distortions.     

Bimanual coordination dynamics in poststroke hemiparetics

Poststroke hemiparetic individuals (n = 9) and a control group (n = 9) completed a frequency-scaled circle-drawing task in unimanual and bimanual conditions. Measures of intralimb spatial and temporal task accuracy and interlimb coordination parameters were analyzed. Significant reductions in task performance were seen in both limbs of the patients and controls with the introduction of bimanual movement. Spatial performance parameters suggested that the 2 groups focused on different hands during bimanual conditions. In the controls, interlimb coordination variables indicated predictable hand dominance effects, whereas in the patient group, dominance was influenced by the side of impairment and prior handedness of the individual. Therefore, in this particular bimanual task, performance improvements in the hemiplegic side could not be elicited. Intrinsic coupling asymmetries between the hands can be altered by unilateral motor deficits.     

Effect of postural instability on drawing errors in children: a synchronized kinematic analysis of hand drawing and body motion

To investigate the role that postural stability plays in fine motor control, we assessed kinematics of the head, shoulder, elbow, and the pen during an accuracy drawing task in 24 children. Twelve children were classified into an accurate drawing (AD) group and 12 children into an inaccurate drawing (ID) group based on a manual dexterity task from the movement assessment battery for children [Henderson, S. E., & Sugden, D. A. (1992). Movement assessment battery for children. London: Psychological Corporation.]. Their parents completed a questionnaire to assess children's inattention, hyperactivity, and impulsivity. An electromagnetic tracking system was used to monitor 3-D kinematic data of the body parts, while 2-D kinematic data of pen movement was simultaneously collected from a computer digitizer tablet. If a sudden body motion (1cm/s) occurred within a time window from one second prior to the onset of the drawing error to the end of the error, we considered that the error coincided with the extraneous body movement. For each drawing trial, the coincidence rate was computed as (number of coincidences)/(number of errors). The ID group had a significantly higher coincidence rate of head and shoulder movements compared with elbow movements, whereas coincidence rates did not differ between the three body parts in the AD group. Parental ratings of children's behavioral ratings of inattention, hyperactivity, and impulsivity were not correlated with the coincidence rates. The results indicated that inaccurate drawing was a result of postural instability rather than fidgeting caused by inattention or hyperactivity/impulsivity.     

Roles of Visual Information for Control of Reaching Movements in Children

Poststroke hemiparetic individuals (n = 9) and a control group (n = 9) completed a frequency-scaled circle-drawing task in unimanual and bimanual conditions. Measures of intralimb spatial and temporal task accuracy and interlimb coordination parameters were analyzed. Significant reductions in task performance were seen in both limbs of the patients and controls with the introduction of bimanual movement. Spatial performance parameters suggested that the 2 groups focused on different hands during bimanual conditions. In the controls, interlimb coordination variables indicated predictable hand dominance effects, whereas in the patient group, dominance was influenced by the side of impairment and prior handedness of the individual. Therefore, in this particular bimanual task, performance improvements in the hemiplegic side could not be elicited. Intrinsic coupling asymmetries between the hands can be altered by unilateral motor deficits.     

Cognitive activity shifts the attractors of bimanual rhythmic coordination

The attractors of bimanual rhythmic coordination are given as the solutions of a motion equation in relative phase. How are those attractors affected by cognitive activity? In 3 experiments, participants (N = 10 in Experiments 1 and 2; N = 5 in Experiment 3) were required to produce in-phase or antiphase coordination while they either did or did not perform an information-reduction task. The average absolute deviation from in-phase (0 degrees ) and antiphase (180 degrees ) satisfying a particular parameterization of the motion equation was amplified by cognitive activity. That amplification of absolute phase shift was the same for both in-phase and antiphase coordination. Furthermore, the amplification (in degrees) increased linearly with the magnitude of cognitive activity (in bits). Cognitive activity had limited influence on the variability of relative phase and did not affect its average signed deviation. Collectively, the results suggest that cognitive activity produces a shift in the attractors of bimanual coordination dynamics that is directionally nonspecific and is independent of movement speed, detuning, and the in-phase-antiphase distinction.     

Hypothesis testing in patients with chronic progressive multiple sclerosis

Patients with chronic progressive MS (N = 38) were compared with an age and education matched medical control group (N = 19) on a visual discrimination task designed to evaluate hypothesis testing and focusing behavior. Thirty-three MS patients (85%) and all control patients were able to formulate and use hypotheses, but MS patients were less likely to employ strategies leading to a correct solution. Furthermore, MS patients were more likely to perseverate with one strategy despite negative verbal feedback. Five MS patients were unable to formulate hypotheses. These findings suggest that MS patients have impaired cognitive functioning in addition to previously reported problems with memory.     

Effects of spatial and motor demands in handwriting

Four experiments were conducted to study response programming in handwriting tasks. Twelve right-handed subjects wrote acoustically presented words and phrases, and their handwriting was digitally recorded. Changes in latency, movement time, trajectory length, and pen pressure were studied as a function of response complexity (i.e., word length, complexity of initial letter, and spacing distance). The lengthening of the spatiotemporal parameters preceding the more complex structures is interpreted to be a reflection of the effects of mental load. The results further indicate that the choice of a programming strategy is dependent on the structural complexity of the task. Writing pressure decreased as a function of increased sequence length. The findings support a hierarchical model of handwriting.     

Effects of Spatial and Motor Demands in Handwriting

Four experiments were conducted to study response programming in handwriting tasks. Twelve right-handed subjects wrote acoustically presented words and phrases, and their handwriting was digitally recorded. Changes in latency, movement time, trajectory length, and pen pressure were studied as a function of response complexity (i.e., word length, complexity of initial letter, and spacing distance). The lengthening of the spatiotemporal parameters preceding the more complex structures is interpreted to be a reflection of the effects of mental load. The results further indicate that the choice of a programming strategy is dependent on the structural complexity of the task. Writing pressure decreased as a function of increased sequence length. The findings support a hierarchical model of handwriting.     

Questioning implicit motor learning as instantiated by the pursuit-tracking task

The effect of concurrent visual feedback on the implicit learning of repeated segments in a task of pursuit tracking has been tested. Although this feedback makes it possible to regulate the positional error during the movement, it could also induce negative guidance effects. To test this hypothesis, a first set of participants (N=42) were assigned to two groups, which performed either the standard pursuit-tracking task based on the experimental paradigm of Pew ( 1974 ; group F-ST), or a task called "movement reproduction" in which the feedback was suppressed (group noF-ST). A second set of participants (N=26) performed in the same feedback condition groups but in a dual-task situation (F-DT and noF-DT; Experiment 2). The results appear to confirm our predictions since the participants in groups without feedback, contrary to those in groups with feedback, succeeded with practice in differentiating their performances as a function of the nature of the segments (repeated or nonrepeated) both in simple (Experiment 1) and in dual-task (Experiment 2) situations. These experiments indicate that the feedback in the pursuit-tracking task induces a guidance function potentially resulting in an easiness tracking that prevents the participants from learning the repetition.     

Transient Effects of Gaze Stability Exercises on Postural Stability in Patients With Posterior Circulation Stroke

The authors sought to investigate if short-term gaze stability exercises have an effect on postural stability of dynamic standing during neck movement in patients with posterior circulation stroke (PCS). Patients in both PCS and non-PCS groups were assigned to either an intervention or control group. The intervention group performed the gaze stability exercises for 10 min while the control group was merely resting. The center of pressure velocity was calculated to evaluate the postural stability. After intervention, PCS and non-PCS showed a significant reduction in center of pressure velocity during dynamic standing with eyes closed condition, and the PCS group showed a significant improvement in eye-opened condition. This study indicated that gaze stability exercises improve PCS patients' postural control, especially during dynamic standing.     

Effects of anger suppression on pain severity and pain behaviors among chronic pain patients: evaluation of an ironic process model

OBJECTIVE: Evidence for links between anger inhibition or suppression and chronic pain severity is based mostly on studies with correlation designs. Following from ironic process theory, we proposed that attempts to suppress angry thoughts during provocation would increase subsequent pain intensity among chronic low back pain (CLBP) patients, and do so through paradoxically enhanced accessibility of anger. DESIGN: CLBP patients (N = 58) were assigned to suppression and nonsuppression conditions while performing a computer maze task with a harassing confederate. A structured pain behavior task (SPBT) followed. MAIN OUTCOME MEASURES: Self-reported anger, anxiety, and sadness following maze task. Self-reported pain severity and number of observed pain behaviors during SPBT. RESULTS: Patients told to suppress during provocation: (a) reported greater anger following the maze task, reported greater pain intensity during the SPBT, and exhibited more pain behaviors than patients not suppressing; (b) postmaze anger levels significantly mediated group differences on pain behaviors. CONCLUSION: Attempts by CLBP patients to suppress anger may aggravate pain related to their clinical condition through ironically increased feelings of anger.     

The Learning of Programmed- and Feedback-Based Processes Controlling the Production of a Positioning Response in Two Dimensions

Two experiments were conducted to investigate the learning of the programmed- and feedback-based processes controlling the production of a slow, self-paced positioning response in two dimensions (direction and extent) in the horizontal plane. Both experiments had two phases: an acquisition phase of 60 trials with KR, followed by a KR withdrawal phase of 20 trials. In Experiment 1, one group (N=15) had visual feedback about the ongoing movement and the other group (N=15) did not. In Experiment 2, one group (N=15) practiced initiating the response in the criterion direction and moving the criterion extent, whereas, the other group (N=15) practiced initiating the response in the criterion direction and moving randomly varied extents. The results of Experiment 1 indicated that the learning of a programmed-based process is a gradually acquired freedom from visual feedback. Experiment 2 revealed that a programmed-based process can be learned independent of a feedback-based process.     

The learning of programmed- and feedback- based processes controlling the production of a positioning response in two dimensions

Two experiments were conducted to investigate the learning of the programmed- and feedback-based processes controlling the production of a slow, self-paced positioning response in two dimensions (direction and extent) in the horizontal plane. Both experiments had two phases: an acquisition phase of 60 trials with KR, followed by a KR withdrawal phase of 20 trials. In Experiment 1, one group (N=15) had visual feedback about the ongoing movement and the other group (N=15) did not. In Experiment 2, one group (N=15) practiced initiating the response in the criterion direction and moving the criterion extent, whereas, the other group (N=15) practiced initiating the response in the criterion direction and moving randomly varied extents. The results of Experiment 1 indicated that the learning of a programmed-based process is a gradually acquired freedom from visual feedback. Experiment 2 revealed that a programmed-based process can be learned independent of a feedback-based process.     

Waking ultradian rhythms of performance and motility in hyperkinetic and normal children

Waking ultradian rhythms in a visual performance task (detections and false positives) and in motility (global body movements and segmental limb movements during the task, and segmental limb movements during off-task periods) were examined in groups of nonmedicated hyperkinetic (HK) children (N = 11) and matched normal controls (N = 11). Testing was conducted for 5 minutes every 15 minutes (with 10-minute "rest periods") over a 6-hour period on 2 consecutive days. Increased limb movement (p less than .01) during off-task periods on both days. Increased limb movement in HK subjects during the task was marginally significant (p less than .06) on one day. False positives and global body movements failed to differentiate the groups. With regard to ultradian rhythmicity, some subjects in both groups showed evident ultradian peaks, which were present across a wide range of frequencies in one or more variables. There were no significant differences in the incidence of the period of evident ultradian peaks between the two groups.