DEVELOPMENT OF A NEXT GENERATION OF AN ARTIFICIAL EXTREMITY SYSTEM CAPABLE OF GENERATING AND GIVING ARTIFICIAL SENSATIONS TO SUBJECTS WITH HIGH-GRADE REALITY

该项目的目标是开发一种能够感知机械刺激的人工手臂系统，然后将这些刺激传递给受试者，以便受试者将刺激体验为相应的躯体感觉。方法：根据人工手臂上传感器的输出，电刺激感觉神经纤维，使其支配单个机械感受器单位;将钨微电极插入正中神经，固定在可记录单个SA机械感受器单位活动的位置。然后用相同的微电极使用250 μsec持续时间的方波脉冲进行电微刺激。以不同方式改变刺激脉冲的幅度和频率，并建立了微电刺激特性与诱发压力感觉强度和面积之间的定性和定量关系。 ...更多信息 研究过了。在本试验中，通过心理物理学方法（例如极限法、调整法或升降法）定量评估诱发压力感觉的主观强度。为了使该技术可用于实际临床应用，需要同时刺激大量和各种神经纤维。我们还研究了当电刺激分别支配不同的单个机械感受器单位的多个感觉神经纤维时，对诱发感觉及其投射面积的影响，结果表明，诱发压力感觉的主观大小似乎与频率的正幂有关;然而，电刺激的幅度基本上没有变化。投影面积不受振幅和频率的影响。关于多个感觉神经纤维的同时刺激，迄今为止的结果表明，当两个机械感受器单位同时接受电刺激时，所诱发的感觉分别成为关于投射面积、感觉种类和大小的简单相加，并且没有发生“非线性”现象。根据这些结果，我们使用与上述相同的技术开发了人造手臂系统的原型。使用机器人手系统（具有人手的形状）作为人工臂系统;其手指和手掌在对应于受试者手的投影区域（即，单个机械感受器单元产生感觉的区域）的区域上覆盖有压力传导橡胶片。然后对压力传导橡胶施加压力;微型计算机使用压力传导橡胶的输出电压来确定刺激感觉神经纤维的电脉冲的频率，然后这些电脉冲通过钨微电极输出到感觉神经纤维。由刺激诱发的感觉的主观强度由受试者使用载玻片体积等来描述;将这些主观评价及其随时间的变化与施加到机器人手的压力传导橡胶上的刺激强度进行比较。该系统以令人满意的方式工作，并且受试者可以感觉到由施加到机器人手的压力传导橡胶的压力引起的相应区域处的压力感觉。施加到压力传导橡胶的压力和诱发感觉的主观强度之间也有很好的相关性。少

The goal or this project was to develop an artificial arm system capable of sensing mechanical stimuli and then transferring these stimuli to the subject so that the subject experiences the stimuli as the corresponding somatic sensations. The technique we used consisted of electrically stimulating sensory nerve fibers, each of which innervates a single mechanoreceptor units, in accordance with the output of the sensors on the artificial arm.A tungsten microelectrode was inserted percutaneously into the median nerve, and fixed at a point where the activities of a single SA mechanoreceptor unit could be recorded. Electrical microstimulation was then performed with the same microelectrode using square-wave pulses of 250 μsec duration. The amplitude and the frequency of the stimulation pulses were altered in various ways, and qualitative and quantitative relationship between the properties of the micro-electrical stimulation and the intensities and areas of the evoked pressure sensations w … More ere studied. In this trials, the subjective intensities of the evoked pressure sensation were evaluated quantitatively by means of psychophysical methods (such as method of limits, method of adjustment, or up-and-down method.In order for this technique to be acceptable for actual clinical use, it is necessary to stimulate both a large number and various kinds of nerve fibers simultaneously. We investigated also how an evoked sensation and its projected area are affected when electrical stimulation is given simultaneously to multiple sensory nerve fibers each of which separately innervate different single mechanoreceptor unit.As a result, the subjective magnitude of the evoked pressure sensation was appeared to be related to a positive power of the frequency ; however, there was essentially no change in the amplitude of the electrical stimulation. The projected area was affected neither by the amplitude nor the frequency. With regard to simultaneous stimulation of multiple sensory nerve fibers, results so far indicated that the sensation evoked when two mechanoreceptor units underwent simultaneous electrical stimulation became a simple addition concerning the projected areas, kinds of sensation, and the magnitude, respectively, and no "non-linear" phenomena took place.According to these results, we developed a prototype of an artificial arm system using the same technique as stated above. A robot hand system (with the shape of a human hand) was used as an artificial arm system ; its fingers and palm was covered with a sheet of pressure-conductive rubber over the area corresponding to the projected area of the subject's hand (i.e. the area over which the single mechanoreceptor unit produces a sensation). Pressure was then applied to the pressure-conductive rubber ; a microcomputer used the output voltage of the pressure-conductive rubber to determine the frequency of the electrical pulses for stimulating the sensory nerve fiber, and these electrical pulses were then output to the sensory nerve fiber via the tungsten microelectrode. The subjective intensities of the sensations evoked by the stimulation were described by the subjects using a slide volume, etc. ; these subjective evaluations and their changes with respect to time were compared with the strengths of the stimuli applied to the pressure-conductive rubber of the robot hand.The system worked in a satisfactory manner, and the subjects could feel the pressure sensation at the corresponding area resulting from the pressure that was applied to the pressure conductive-rubber of the robot hand. There was also a good correlation between the pressure applied to the pressure-conductive rubber and the subjective intensities of the evoked sensations. Less