Jürgen Konczak

Predicting Children's Overarm Throw Ball Velocities from Their Developmental Levels in Throwing

Abstract This study examined the movement process-product relationship from a developmental perspective. The authors used multiple regression to investigate the changing relationship between qualitative movement descriptions of the overarm throw and the throwing outcome, horizontal ball velocity. Seventeen girls and 22 boys were filmed longitudinally at ages 6, 7, 8, and 13 years. Their movements were assessed using Robertons (Roberton & Halverson, 1984) developmental sequences for action of the humerus, forearm, trunk, stepping and stride length. The sequences accounted for 69–85% (adjusted) of the total velocity variance each year. The components that best predicted ball velocity changed over time, although humerus or forearm action always accounted for considerable variance. Gender was a good predictor of ball velocity, but if the developmental descriptions were entered first in a stepwise regression, gender then explained no more than 2% additional variance.

Depth perception in cerebellar and basal ganglia disease

There is increasing evidence that the cerebellum and the basal ganglia serve not only a role in motor control but also in visual perception. Patients with Parkinson’s disease (PD) as well as patients with cerebellar lesions exhibit impairments of vision that are not fully explained by ocular motor deficits. It is less clear to which extent these visual deficits contribute to an impaired control of visually guided movements. This study examined whether a dysfunction of the cerebellum or the basal ganglia induces impairments in depth perception, which affect action. We employed an illusionary display, the Ames trapezoidal window, to determine the ability of PD patients (n=10) and patients with spinocerebellar ataxia (SCA) (n=6) to process depth cues when estimating object slant. Participants either pointed to the edges of the window (motor judgement) or verbally indicated the perceived orientation of the display (verbal judgement). To control for ocular and limb motor deficits, participants judged the slant of a non-illusionary display in a second task. Slant estimation of the non-illusionary window was not impaired in either patient group when compared to control subjects (all P>0.2). In contrast, SCA as well as PD patients exhibited significantly greater slant estimation errors than controls when pointing to the illusionary window (P=0.005). In addition, both patient groups made larger errors than controls in their verbal judgements during binocular viewing of the illusion (P=0.005), but not during monocular viewing (P>0.2). In sum, the present findings point towards a role for both the basal ganglia and cerebellum for the processing of visual information about depth. Since the deficits were seen both in the context of action and perception and were only partially reconciled by the availability of binocular depth cues, we conclude that basal ganglia as well as cerebellar disease may affect the visual perception of depth.

Robot-aided developmental assessment of wrist proprioception in children

BackgroundSeveral neurodevelopmental disorders and brain injuries in children have been associated with proprioceptive dysfunction that will negatively affect their movement. Unfortunately, there is lack of reliable and objective clinical examination protocols and our current knowledge of how proprioception evolves in typically developing children is still sparse.MethodsUsing a robotic exoskeleton, we investigated proprioceptive acuity of the wrist in a group of 49 typically developing healthy children (8–15 years), and a group of 40 young adults. Without vision participants performed an ipsilateral wrist joint position matching task that required them to reproduce (match) a previously experienced target position. All three joint degrees-of-freedom of the wrist/hand complex were assessed. Accuracy and precision were evaluated as a measure of proprioceptive acuity. The cross-sectional data indicating the time course of development of acuity were then fitted by four models in order to determine which function best describes developmental changes in proprioception across age.ResultsFirst, the robot-aided assessment proved to be an easy to administer method for objectively measuring proprioceptive acuity in both children and adult populations. Second, proprioceptive acuity continued to develop throughout middle childhood and early adolescence, improving by more than 50% with respect to the youngest group. Adult levels of performance were reached approximately by the age of 12 years. An inverse-root function best described the development of proprioceptive acuity across the age groups. Third, wrist/forearm proprioception is anisotropic across the three DoFs with the Abduction/Adduction exhibiting a higher level of acuity than those of Flexion/extension and Pronation/Supination. This anisotropy did not change across development.ConclusionsProprioceptive development for the wrist continues well into early adolescence. Our normative data obtained trough this novel robot-aided assessment method provide a basis against which proprioceptive function of pediatric population can be compared. This may aid the design of more effective sensorimotor intervention programs.

Association between vestibuloocular reflex suppression during smooth movements of the head and attention deficit in progressive supranuclear palsy

With head movement, suppression of vestibular inputs during visual exploration is necessary not only for reorienting gaze, but also to direct attention to new visual targets. People with progressive supranuclear palsy (PSP) have difficulty suppressing the vestibuloocular reflex (VOR) and it was hypothesized that the magnitude of VOR suppression deficit correlates with the degree of degradation of attention and visuospatial performance. We evaluated cognitive and visuomotor function in 8 subjects with PSP (4 men and 4 women; ages 59–83 years). Gaze control was studied by measuring the accuracy of eye–head coordination during passive vertical and horizontal head‐on‐trunk movements. Fixation was assessed when subjects viewed either an earth‐fixed or head‐fixed target. A gaze fixation score (GFS) was calculated to represent the amount of error between eye and head movement in each plane (eye–head root mean square error normalized to the range of head rotation). The vertical but not horizontal GFS during attempted suppression of the VOR was significantly related to attention (r = −0.70; P = 0.05) and visuospatial ability (r = −0.76; P = 0.03). These findings suggest that the ability to suppress the VOR during vertical smooth movements of the head is associated with the magnitude of cognitive deficit in PSP.

Development of Proprioceptive Acuity in Typically Developing Children: Normative Data on Forearm Position Sense

This study mapped the development of proprioception in healthy, typically developing children by objectively measuring forearm position sense acuity. We assessed position sense acuity in a cross-sectional sample of 308 children (5–17 years old; M/F = 127/181) and a reference group of 26 healthy adults (18–25 years old; M/F = 12/14) using a body-scalable bimanual manipulandum that allowed forearm flexion/extension in the horizontal plane. The non-dominant forearm was passively displaced to one of three target positions. Then participants actively matched the target limb position with their dominant forearm. Each of three positions was matched five times. Position error (PE), calculated as the mean difference between the angular positions of the matching and reference arms, measured position sense bias or systematic error. The respective standard deviation of the differences between the match and reference arm angular positions (SDPdiff) indicated position sense precision or random error. The main results are as follows: First, systematic error, measured by PE, did not change significantly from early childhood to late adolescence (Median PE at 90° target: −2.85° in early childhood; −2.28° in adolescence; and 1.30° in adults). Second, response variability as measured by SDPdiff significantly decreased with age (Median SDPdiff at 90° target: 9.66° in early childhood; 5.30° in late adolescence; and 3.97° in adults). The data of this large cross-sectional sample of children document that proprioceptive development in typically developing children is characterized as an age-related improvement in precision, not as a development or change in bias. In other words, it is the reliability of the perceptual response that improves between early childhood and adulthood. This study provides normative data against which position sense acuity in pediatric patient populations can be compared. The underlying neurophysiological processes that could explain the observed proprioceptive development include changes in the tuning of muscle spindles at the spinal level, the maturation of supraspinal somatosensory pathways and the development of interhemispheric callosal connections responsible for the transfer of somatosensory information.

Robot-Assisted Proprioceptive Training with Added Vibro-Tactile Feedback Enhances Somatosensory and Motor Performance

This study examined the trainability of the proprioceptive sense and explored the relationship between proprioception and motor learning. With vision blocked, human learners had to perform goal-directed wrist movements relying solely on proprioceptive/haptic cues to reach several haptically specified targets. One group received additional somatosensory movement error feedback in form of vibro-tactile cues applied to the skin of the forearm. We used a haptic robotic device for the wrist and implemented a 3-day training regimen that required learners to make spatially precise goal-directed wrist reaching movements without vision. We assessed whether training improved the acuity of the wrist joint position sense. In addition, we checked if sensory learning generalized to the motor domain and improved spatial precision of wrist tracking movements that were not trained. The main findings of the study are: First, proprioceptive acuity of the wrist joint position sense improved after training for the group that received the combined proprioceptive/haptic and vibro-tactile feedback (VTF). Second, training had no impact on the spatial accuracy of the untrained tracking task. However, learners who had received VTF significantly reduced their reliance on haptic guidance feedback when performing the untrained motor task. That is, concurrent VTF was highly salient movement feedback and obviated the need for haptic feedback. Third, VTF can be also provided by the limb not involved in the task. Learners who received VTF to the contralateral limb equally benefitted. In conclusion, somatosensory training can significantly enhance proprioceptive acuity within days when learning is coupled with vibro-tactile sensory cues that provide feedback about movement errors. The observable sensory improvements in proprioception facilitates motor learning and such learning may generalize to the sensorimotor control of the untrained motor tasks. The implications of these findings for neurorehabilitation are discussed.

Dual task effect on postural control in patients with degenerative cerebellar disorders

BackgroundThe cerebellum plays an important role for balance control and the coordination of voluntary movements. Beyond that there is growing evidence that the cerebellum is also involved in cognitive functions. How ataxic motor symptoms are influenced by simultaneous performance of a cognitive task, however, has rarely been assessed and some of the findings are contradictory. We assessed stance in 20 patients with adult onset degenerative almost purely cerebellar disorders and 20 healthy controls during single and dual task conditions (verbal working memory task). To objectively measure postural sway and the impact of somatosensory, visual and vestibular inputs we used static and dynamic posturography with the Sensory Organization Test (SOT).ResultsIn both groups, cerebellar patients and controls, dual tasking reduced all sway parameters. Reduction of sway path was higher in cerebellar patients and increased with the difficulty of the postural task. The frequency of falls was higher in the patients group especially during the more challenging conditions and dual task performance in particular increased the risk of falls in cerebellar patients.ConclusionDual task conditions had a larger impact on sway parameters in patients with chronic cerebellar disorders than in healthy controls and lead to an increased risk of falls. As performing two tasks simultaneously is common and therefore important in daily life dual task exercises should be part of physical therapy programs for cerebellar patients.

Constraint‐induced movement therapy in Parkinson's disease

Constraint-induced movement therapy (CIMT), or forced limb use, is a rehabilitation technique that restricts movement of an unaffected upper extremity to force use of a paretic limb. CIMT has been shown to induce cortical reorganization and functional improvement in patients with stroke,1 as well as those with focal hand dystonia.2–4 Parkinson’s disease (PD) is managed with pharmacotherapy and adjunctive physical therapy. Initial work with 6-hydroxydopamine-lesioned rats hinted that CIMT may be beneficial in PD, and suggested that function may be improved via sparing of striatal dopamine, its metabolites, and the expression of the monoamine transporter.5,6 To date, no systematic clinical trials have investigated the effects of CIMT in PD patients. We now report the results of an open-label nonrandomized treatment trial of CIMT in mild-to-moderate PD. The effects of CIMT were assessed with the Unified Parkinson’s Disease Rating Scale (UPDRS), patient and evaluator clinical global impression (CGI) of disease severity, and a motor function assessment (MFA) test of upper limb function. The MFA test was based on previous work7,8 and examined the kinematics of discrete and rhythmical flexion/extension movements of the elbow and wrist. We hypothesized that CIMT of the lessaffected arm in PD would improve function of the more severely affected unrestrained arm. The study was approved by the Institutional Review Board of Fairview-University Medical Center, Minneapolis, Minnesota. Six PD patients, Hoehn and Yahr stage II to III, all righthanded with right-sided symptom onset, were enrolled. Patients were excluded if they had atypical parkinsonism, dementia, clinically significant depression or other psychiatric diagnoses, significant medical illness that might interfere with study participation, or an inability to adhere to the study protocol. The study followed a nonrandomized, repeated-measures, clinical open-label pilot study design with multiple baseline measurements. Subjects came in for the first baseline assessments within 10 days before the start of the CIMT sessions (for a standard history and neurological examination, Mini-Mental status examination, UPDRS, CGI, and kinematic MFA of the upper extremities). MFAs were conducted with a custom-made manipulandum that allows flexion and extension of the wrist (see Fig. 1). Each arm was tested in an aiming task (35 flexion or extension) and a task of synchronizing wrist movement to a distinct tone at two frequencies (2.5 and 4 Hz). Reaction time, movement time, peak velocity, and frequency error (mean difference between produced and required frequency in the synchronization task) were calculated based on the recorded time-position data. Patients refrained from taking antiparkinsonian medications for 12 hours before this assessment (i.e., off assessment). The second visit (baseline 2) included UPDRS, CGI, and MFA measurements in the off state, and occurred within 2 days before initiating CIMT. Therapy sessions ran for 3 hours, 5 days a week, for 2 consecutive weeks. During the intervening weekend, patients were asked to wear their restraint mitten but did not attend therapy sessions. Once therapy commenced and until posttherapy assessments, subjects were asked to wear their mitten for a total of 10 hours per day or for 90% of their waking hours. CIMT was conducted based on shaping therapy, as has been used in previous studies.1,9 Off follow-up assessments were carried out within 2 days after the completion of the 2 weeks of CIMT therapy. Within subjects, preto post-CIMT comparisons of mean values (over trials) were computed. To detect changes between baseline and posttest performance, difference scores were computed and entered into univariate analysis of variance. Correlation analyses were also conducted to determine the strength of the association between baseline motor function and behavioral improvements after CIMT. There were no significant effects of CIMT on UPDRS or CGI scores. We found small but nonsignificant changes in physician and subject ratings. There was no apparent relationship between changes in UPDRS or CGI scores and any demographic variable, although it is noteworthy that both subjects who had changes of at least 2 points on the UPDRS had been diagnosed with PD 5 years before testing. In regards to the aiming task, the mean group peak velocity for the left wrist (i.e., the less-affected side) was expectedly faster than the right (right, 249.5 degrees/sec; left, 219.1 degrees/sec). Mean reaction times were longer for the right than for the left arm (right, 240.4 msec; left, 220.4 msec). Conversely, movement times on average were quicker for the right than for the left arm (right, 724.6 msec; left, 682.9 msec). For the group, CIMT did not systematically improve motor performance of the affected upper limb on any kinematic measure relative to baseline (mean improvements: 2.3% for reaction time; 9.1% for movement time; 6% for peak velocity). Individual patients revealed changes in their kinematics, but these changes were not consistent enough to state that a subgroup of patients might have benefited significantly from CIMT (see Fig. 1B). Finally, we found no consistent effects of the CIMT on the unaffected limb. To our knowledge, this open-label pilot study is the first to explore the effects of CIMT in PD. Overall, we found no substantial or consistent kinematic improvements in the affected limb. The lack of effect was not the result of learning, but could have been related to the study parameters, the patient characteristics, or small sample size. The main result of this study is that CIMT does not seem to benefit those with PD. Given the limited scope of the study, however, we cannot exclude that CIMT may show benefits if conducted over a longer period. In addition, possible benefits might have been masked by our small sample that did not account for individual differences (e.g., gender, age, medication history, and disease severity). In practice, CIMT can be employed relatively easily as it is noninvasive and can be carried out at the patient’s home.

Position Sense Dysfunction Affects Proximal and Distal Arm Joints in Children with Developmental Coordination Disorder

ABSTRACT It is unclear, whether proprioceptive dysfunction in developmental coordination disorder (DCD) is localized affecting only specific joints or whether it is generalized affecting proximal and distal joints. Thus, this study assessed position sense acuity at the elbow and wrist in twenty children with DCD (age: 9–11 yrs.) using a joint position matching paradigm. Position sense bias (systematic error) at either joint was not significantly higher in DCD children when compared to typically developing children (TD). However, DCD children exhibited significantly lower position sense precision (random error) than TD children at both elbow and wrist. That is, response reliability to proprioceptive stimuli is altered in DCD. Our findings are consistent with a view that proprioceptive dysfunction in DCD is generalized in nature.

A robot-aided visuo-motor training that improves proprioception and spatial accuracy of untrained movement

Proprioceptive function can become enhanced during motor learning. Yet, we have incomplete knowledge to what extent proprioceptive function is trainable and how a training that enhances proprioception may influence performance in untrained motor skills. To address this knowledge gap, healthy young adults (N = 14) trained in a visuomotor task that required learners to make increasingly accurate wrist movements. Using a robotic exoskeleton coupled with a virtual visual environment, participants tilted a virtual table through continuous wrist flexion/extension movements with the goal to position a rolling ball on table into a target. With learning progress, the level of difficulty increased by altering the virtual ball mechanics and the gain between joint movement and ball velocity. Before and after training, wrist position sense acuity and spatial movement accuracy in an untrained, discrete wrist-pointing task was assessed using the same robot. All participants showed evidence of proprioceptive-motor learning. Mean position sense discrimination threshold improved by 34%. Wrist movement accuracy in the untrained pointing task improved by 27% in 13/14 participants. This demonstrates that a short sensorimotor training challenging proprioception can a) effectively enhance proprioceptive acuity and b) improve the accuracy of untrained movement. These findings provide a scientific basis for applying such somatosensory-based motor training to clinical populations with known proprioceptive dysfunction to enhance sensorimotor performance.