Kavanagh Justin J, Cross Troy J, Newell Karl M, Morrison Steven
Centre for Musculoskeletal Research, Griffith University, Gold Coast, Australia.
Heart Foundation Research Centre, Griffith University, Gold Coast, Australia, and Division of Cardiovascular Diseases, Mayo Clinic, Rochester, USA.
J Neurol Sci. 2014 Apr 15;339(1-2):69-74. doi: 10.1016/j.jns.2014.01.023. Epub 2014 Jan 24.
The purpose of this study was to investigate hand-finger tremor dynamics when a load was applied to the finger in a group of healthy older adults. Moreover, we sought to determine if projecting a representation of the subject's finger tremor on a target was capable of overcoming the effects of loading so that hand-finger interactions returned to a state that was similar to normal tremor. Eight healthy older males (67 ± 1 year) performed a postural pointing task, where tremor was assessed using lightweight accelerometers attached to the hand and finger. Tremor was then assessed when a laser pointer was attached to the finger and switched off (the load), and then with the laser pointer attached and switched on pointing at targets of 40 mm and 20mm in diameter. The main findings of this study were that 1) loading the finger resulted in a reduction in finger tremor amplitude and increased finger tremor regularity, but no change in hand tremor, 2) loading caused increased hand-finger 8-12 Hz cross wavelet coherence and phase synchrony, and 3) pointing at different targets while the finger was loaded resulted in an increase in finger tremor amplitude, and changes in inter-segmental coupling to the extent that hand-finger dynamics reflected normal unloaded conditions. Overall, these results illustrate that the damping effects of limb loading can be offset, in part, by altering the accuracy demands of the task to make the pointing action more challenging.
本研究的目的是调查在一组健康的老年人中，当手指承受负荷时手部-手指震颤的动态变化。此外，我们试图确定将受试者手指震颤的表现投射到目标上是否能够克服负荷的影响，从而使手部-手指的相互作用恢复到类似于正常震颤的状态。八名健康老年男性（67±1岁）执行了一项姿势指向任务，其中使用附着在手部和手指上的轻质加速度计评估震颤。然后，在将激光指示器附着在手指上并关闭（负荷）时评估震颤，接着在附着激光指示器并打开指向直径为40毫米和20毫米的目标时评估震颤。本研究的主要发现是：1）手指承受负荷导致手指震颤幅度减小且手指震颤规律性增加，但手部震颤无变化；2）负荷导致手部-手指8-12赫兹交叉小波相干性和相位同步增加；3）在手指承受负荷时指向不同目标导致手指震颤幅度增加，并且节段间耦合发生变化，以至于手部-手指动态反映出正常的无负荷状态。总体而言，这些结果表明，通过改变任务的准确性要求以使指向动作更具挑战性，肢体负荷的阻尼效应可以部分抵消。
