Biomedical subjects

Charles J Worringham

Publications and source records attributed to Charles J Worringham.

3 recordsLinked to original sources

PubMed2006

Predictors of driving assessment outcome in Parkinson's disease.

This study evaluated selected clinical and functional tests as predictors of driving safety outcomes in Parkinson's disease (PD) patients. A total of 25 PD patients and 21 age-matched controls, all regular drivers, underwent neurological evaluation and assessment of cognitive, visual, and motor function and a standardized, on-road driving assessment. The capacity of the tests to predict pass/fail driving outcomes was determined by selecting a subset with the highest predictive value from each domain and then subjecting these subsets to discriminant function analysis. Accuracy, sensitivity, specificity, and positive and negative predictive values were determined. Three relatively simple tests from the larger battery predicted passes with relatively high sensitivity (PD, 72.7%; controls, 93.8%; both combined, 85.2%); and moderate specificity (PD, 64.3%; controls, 60.0%; both combined. 63.2%). These tests assessed motor performance (Purdue Pegboard test), contrast sensitivity (Pelli-Robson test), and cognitive function (verbal version of Symbol Digit Modalities test). Adding time since diagnosis for the PD group increased sensitivity to 90.9% and specificity to 71.4%. These simple tests confer more objectivity and predictive power to clinical recommendations for driving, they reflect distinct functions that are necessary for safe driving, and they may be especially useful when on-road assessments are not feasible.

Activities of Daily Living↗

PubMed2002

Practice effects in three-dimensional sequential rapid aiming in Parkinson's disease.

One hypothesized role of the basal ganglia, based largely on findings in Parkinson's disease (PD) patients, is the control of movement sequences. We examined changes in performance with practice of a movement sequence in PD patients and age-matched controls (n = 8 per group). Subjects practiced a complex three-dimensional sequential aiming task over 2 days, completing 180 trials, with the goal to minimize response time within specified accuracy limits. The results indicated that both groups became faster in planning the movement, and both groups moved more quickly through the sequence with practice. The PD group's decrease in movement time occurred primarily within the first 45 trials, whereas the control group continued to improve through the first 150 trials. Flight time (time between targets) to a small target decreased with practice in both groups, but flight time to a large target decreased only in the control group. This finding indicates that error corrective processes are more amenable to practice than ballistic processes in people with PD. There was little evidence that either group improved their performance by planning shorter (lower) trajectories, but rather increased mean velocity. Contact time (time on target) decreased with practice in both groups, and there were no group differences. These data indicate that practice can improve performance, both in planning and in specific execution processes.

Aged↗

PubMed2002

Velocity perception and proprioception.

Proprioceptive information related to position and velocity reaches conscious perception and appears to be processed simultaneously via separate perceptual channels. Determining the fidelity of velocity perception is difficult, however, because of the interaction of distance and timing information in its derivation. There is also a complex relationship between receptor discharge and kinematic variables and thresholds for detection of proprioceptive information are increased during movement. Experiments determined the discrimination thresholds for different movement velocities when i) movement distance remained constant and duration varied; ii) movement duration remained constant and distance varied; iii) movement distance and duration were randomly varied. Discrimination thresholds increased as movement velocity increased. Velocity perception was more accurate when distance and timing cues were available, particularly at higher velocities. These results indicate that all available cues are used to make judgements of movement velocity.

Biomechanical Phenomena↗