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Biomedical subjects

P C van Wieringen

Publications and source records attributed to P C van Wieringen.

10 recordsLinked to original sources
PubMed2000

Coordination disorders in patients with Parkinson's disease: a study of paced rhythmic forearm movements.

Whereas the consequences of Parkinson's disease (PD) for the performance of single-limb movements are well documented (i.e., bradykinesia, akinesia, rigidity, and tremor), fairly little is known about its implications for the coordination between limb movements. To help resolve this situation an experiment was conducted in which 11 PD patients and 11 control subjects performed rhythmic forearm movements at a comfortable amplitude in the in-phase, antiphase, and single-arm mode at pacing frequencies ranging from 0.5 to 3 Hz. The PD group displayed marked coordination problems over and above the known clinical motor symptoms of PD. The performance of both the in-phase and antiphase modes was significantly affected in the PD group compared to the control group; furthermore, the variability of relative phase was significantly increased in this group. These observations were not caused by problems to synchronize the movements with the external pacing signal. In addition to the bimanual coordination problems, involuntary mirror movements (MM) were observed in the single-arm control trials that were significantly larger in the PD group (4.4% of the amplitude of the moving arm) than in the control group (2.3%), suggesting a reduced ability to suppress a basic in-phase coupling of the arms. In the PD group, MM were largest during movements of the least-affected arm. These parkinsonian coordination problems are interpreted in terms of recent evidence on the neural organization of bimanual coordination, suggesting that they are due to cortical rather than callosal dysfunction.

Aged↗
PubMed1998

Coordination in prehension. Information-based coupling of reaching and grasping.

Prehension involves the coordination of a reaching and a grasping movement, such that the hand opens and closes in tune with the transport of the hand to the object to be grasped. To investigate this coordination, we focused on the transition from hand opening to hand closing in the grasping component of prehension. Earlier research has suggested that the time taken to close the hand remains constant over varying reaching amplitudes. In the present experiment, in which subjects reached for objects at six different distances and for objects that moved away from them at three different, constant speeds, hand-closure time was found to vary as a function of experimental conditions. Moreover, initiation of hand closure did not occur at a constant value of the (perceptually available) first-order time remaining until contact with the object. However, the variations observed, occurring as a function of initial hand-object distance and object speed, could be accounted for by an abstract dynamical model of perceptually driven postural changes.

Adult↗
PubMed1995

Frequency-induced phase transitions in bimanual tapping.

The stability of bimanual performance of the frequency ratios 3:8 and 5:8 was examined from the perspective of the sine circle map and the associated Farey mode-locking hierarchy. By gradually increasing movement frequency, abrupt transitions from the initial frequency ratios to other frequency ratios were induced. In general, transitions occurred to frequency ratios that were near the initial frequency ratio but lower in the Farey ordering, and, hence, of higher stability in the sine circle map. A fair percentage of these transitions were to unimodularly related ratios. The transition routes from 3:8 and 5:8 remained largely unaffected by extensive practice of the lower-order ratios 2:5 and 3:5. Collectively, these results suggest that (i) bimanual tapping occurs in a domain in which frequency-locked states either overlap or are located sufficiently close to each other to make stochastic switching possible (coupling parameter K > 1 or close to 1); (ii) the overall stability of these frequency-locked states decreases as movement frequency increases (due to a decrease in K); and, consequently, (iii) the probability of transitions to nearby frequency ratios increases as movement frequency increases, due to the differential stability of the frequency locks.

Acoustic Stimulation↗
PubMed1991

Acquiring an attacking forehand drive: the effects of static and dynamic environmental conditions.

Two groups of 10 novice subjects each were trained to perform attacking forehand drives in table tennis and land the balls as fast and as accurately as possible onto a target on the opposite side of the net under two different training conditions. Under the static training condition, the balls were to be struck from a constant position, and under the dynamic training condition, balls approached the subjects in a normal way. Both groups were tested under dynamic conditions prior to and after four days of training, during which they received 1,600 practice trials. Both groups of subjects were shown to increase the number of balls that landed on the target, and learning was also evident from an increased consistency of the direction of travel of the bat at the moment of ball/bat contact. However, no increase in consistency was found for the location of the bat at the moment of ball/bat contact and for the movement times. Thus, learning can occur in the absence of externally generated time-to-contact information, but this is not due to the establishment of a consistent movement form. Learning appears to progress from control at the moment of ball/bat contact backward, toward the moment of initiation.

Adolescent↗
PubMed1990

The functional recovery of stroke: a comparison between neuro-developmental treatment and the Brunnstrom method.

The relative efficacy of Neuro-Developmental Treatment (N.D.T.) versus the Brunnstrom method was studied from the perspective of the functional recovery of stroke patients. An alternating treatment design (B-C-B-C) was used. Each intervention phase lasted 5 weeks. The functional recovery of the patients was assessed every week by using the Barthel Index and the Action Research Arm test, by registering walking velocity, and by performing gait analysis. At the start and at the end of each intervention phase, neurological and neuropsychological assessments took place. Time series analysis indicated that for one patient only, walking speed progressed more during the Brunnstrom phases than the N.D.T. phases. This result did not generalize towards other parameters or patients studied. For upper extremity function and maximum walking speed, a high correlation was found between the week post stroke in which the patient showed the first signs of recovery and the end condition after 20 weeks.

Adult↗
PubMedDate not supplied

The transfer of scanning training effects in visual inattention after stroke: five single-case studies.

The transfer effects of scanning training of right-brain-damaged stroke patients with visual inattention have been studied. Five patients were treated according to a B-C-B-D design. The first B phase lasted for 2, 4, or 6 weeks, whereas the other intervention phases had a fixed duration of 2 weeks. During all phases physical therapy was given. Additionally, occupational therapy was applied during the B phases, training on a scanning apparatus during the C phase, and training on reading tasks during the D phase. At least three times in each intervention phase, performance was measured using a computerized visual scanning test, a line bisection test, and a letter cancellation test. In addition, wheelchair navigation was assessed. For four out of the five patients a significant positive effect of visual scanning training on visual scanning behaviour was found. This effect, however, appeared to be restricted to the task which was specifically trained. Over the group as a whole no evidence could be found for any transfer of visual scanning training effects to the domain of gross motor skills.

Activities of Daily Living↗