Department of Neuroscience and the Krieger Mind/Brain Institute, The Johns Hopkins University, Baltimore, Maryland, USA.
Prog Brain Res. 2011;192:69-81. doi: 10.1016/B978-0-444-53355-5.00005-1.
In this chapter, we discuss the neurophysiological basis of how to provide sensory feedback to users with an upper limb prosthesis and discuss some of the theoretical issues that need to be considered when directly stimulating neurons in the somatosensory system. We focus on technologies that are currently available and discuss approaches that are most likely to succeed in providing natural perception from the artificial hand to the user. First, we discuss the advantages and disadvantages of providing feedback by stimulating directly the remaining afferents that originally innervated the arm and hand. In particular, we pay close attention to the normal functional roles that the peripheral afferents play in perception. What are the consequences and implications of stimulating these afferents? We then discuss whether it is reasonable to stimulate neurons in the ascending pathways that carry the information from the afferents to the cortex or directly in neurons in the primary somatosensory cortex. We show that for some modalities there are advantages for stimulating in the spinal cord, while for others it is advantageous to stimulate directly in the somatosensory cortex. Finally, we discuss results from a current experiment in which we used electrical stimuli in primary somatosensory cortex to restore the percept of the intensity of a mechanical probe indented into the hand. The results suggest that the simple percept of stimulus intensity can be provided to the animal from a single finger using four electrodes. We propose that significantly more electrodes will be needed to reproduce more complex aspects of tactile perception.
在本章中，我们讨论了为上肢假肢用户提供感觉反馈的神经生理学基础，并讨论了在直接刺激躯体感觉系统中的神经元时需要考虑的一些理论问题。我们专注于当前可用的技术，并讨论了最有可能成功地从人工手向用户提供自然感知的方法。首先，我们讨论了通过直接刺激原本支配手臂和手的剩余传入神经来提供反馈的优缺点。特别是，我们密切关注外周传入神经在感知中正常的功能作用。刺激这些传入神经会有什么后果和影响？然后，我们讨论了刺激携带传入信息到大脑皮层的上行通路中的神经元或直接刺激初级躯体感觉皮层中的神经元是否合理。我们表明，对于某些模态，在脊髓中刺激具有优势，而对于其他模态，直接在躯体感觉皮层中刺激具有优势。最后，我们讨论了目前一项实验的结果，该实验使用初级躯体感觉皮层中的电刺激来恢复机械探针插入手部时的强度知觉。结果表明，可以使用四个电极从单个手指向动物提供刺激强度的简单知觉。我们提出，需要更多的电极来重现触觉感知的更复杂方面。
