| Summary: | 碩士 === 國立成功大學 === 物理治療研究所 === 95 === Objective: Motor learning is the process of acquisition of movement skill due to repetitive practicing. In general, learning a new motor skill associated with development of a new internal model; Provided that different motor skills share some inherent components of internal models, the effect of learning transfer would be evident. Several previous studies have investigated the motor transferring across limbs, however little attention was paid to the extent to which a complex movement can be benefited from practicing a simple act beforehand, as well as the dependence on visual feedback after learning transfer. In this study, we used the laser system to detect performance of the tracking tasks and associated kinetic tremor to observe the effects of learning transfer on compound sinusoidal tracking consequent to simple sinusoidal tracking with visual feedback. Next, the present study also investigated the significance of visual feedback for tracking task in relation to generalization of internal models.
Methods: Sixteen healthy subjects practiced alternate abduction and adduction with the dominant index finger to couple the position trace with the sinusoidal waves at 0.25Hz and 0.75Hz. Each practice trial consisted of eight 40-second trials which were interlaced with a 40 second resting interval. Pre-test and post-test contained four different position tracking tests: 0.25Hz/0.75Hz sinusoidal tracking, and compound wave (0.25Hz +0.75Hz) with and without visual feedback. Re-test was performed fifteen minutes later after post-test to minimize fatigue effect. Position trace and kinetic tremor were recorded with the laser system. Cross correlation and root mean square (RMS) of position trace and target curves were determined to characterize waveform congruency and performance errors. RMS and tremor peaks in the 1-4 Hz and 6-12 Hz of kinetic tremor were calculated. The amounts of relative changes in all features of kinetic tremor were contrasted among all tracking tests after learning the simple sinusoidal tracking.
Results: After practicing simple sinusoidal tracking, the waveform congruency improved and the total errors decreased in the compound tracking tasks. In reference to simple tracking task, the waveform congruency of compound tracking task with visual feedback was much improved, though reduction in performance errors was not completely dependent on provision of visual feedback. Quantitative tremor analysis showed that practicing resulted in a greater decrement in tremor amplitude in the tests of the 0.75Hz sinusoidal tracking and compound sinusoidal tracking. Specifically, 1-4 Hz tremor peak reduced for all tracking tests, though the amount of relative decrement in 1-4 Hz tremor peak did not differ among various tracking tests. Noticeably, the 6-12 Hz tremor peak decreased merely in the 0.75Hz tracking task after learning the simple sinusoidal tracking task.
Conclusion: After simple sinusoidal tracking, motor learning was evident which could be transferred efficiently to compound position tracking, in support of enhancement of waveform congruency and decrease in mismatch errors. Particularly, visual feedback added to waveform congruency in the compound tracking task. Learning from simple tracking appeared to decrease 1-4 Hz tremor peak during compound position tracking without visual feedback condition, although it was not different among different tracking tests; thus it suggested that low frequency tremor was related to eye-hand coordination. Moreover, modulation of central rhythm related functionally to successful learning in sinusoidal tracking at a higher rate, which is premeditated by open-loop control.
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