Sensory Feedback System

功能性电刺激（FES）对于瘫痪上肢的恢复非常有效。我们研制的微机多通道功能电刺激系统已用于恢复C5-6四肢瘫痪患者的功能性手运动，这些患者不仅丧失了运动功能，而且丧失了感觉功能。为了恢复与FES产生的手部运动有关的感觉，我们研究了皮肤电刺激方法。这类患者仅在肩部以上的上部有皮肤感觉。(1)We研究了肩部皮肤对电刺激的感觉的基本特征：绝对阈值和痛阈值作为刺激的函数，以及它们对脉冲重复频率、频率分辨率、空间分辨率、时间分辨率等的依赖性。(2)We也研究了电的“幻感觉”。受试者可以感觉到两对刺激电极之间的移动感觉。提出了一种有效的体模图像生成方法。施加到两个单独电极的电流脉冲序列的幅度彼此互补地调制;一个增加而另一个减小。调制量必须通过两种刺激的组合来修改，这使得受试者几乎均匀地感觉到融合的图像。本研究揭示了幻象感觉的定性和定量特征。此外，三通道排列可产生大范围运动的体模图像。通过这些方法，可以用最少的电极数将反映手指位移或抓握压力的模拟量转换成平滑移动的体模图像。

Functional Electrical Stimulation(FES) is very efficient for the restoration of the paralyzed upper extremities. Functional hand movements have been restored in C5-6 quadriplegic patients by the microcomputer based multi-channel FES system which we developed.Such patients are deprived of not only motor function but also sensory function. To restore the sensation relating to the FES-produced hand movements, we have studied the electrocutaneous stimulation methods. Such patients have skin sensation only in the upper part above the shoulders.(1)We investigated the basic characteristics of the shoulder skin sensation to the electrical stimulation on the following points ; absolute threshold and pain threshold as a function of stimulation and their dependence on the pulse repetion frequency, frequency resolution, spatial resolution, temporal resolution, etc..(2)We also investigated electrical "phantom sensation". Subject can feel the moving sense between the two pairs of the stimulation electrodes. An effective new method to produce the phantom image are proposed. The amplitude of the current pulse trains applied to two separate electrodes are modulated complementarily to each other ; one increases while the other decreases. The amount of modulation must be modified by the combination of two stimuli which gives subjects almost even sensation of the fused images. Qualitative and quantitative characteristics of the phantom sensation were revealed by this research project. In addition, widely moving phantom images could be produced by three channel arrangement. By these methods, analog quantities which reflect finger displacement or grasping pressure can be converted to smoothly moving phantom images with minimum number of electrodes.