Department of Cell Biology, Physiology and Immunology, Group of Neuroplasticity and Regeneration, Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain.
J Neural Eng. 2011 Jun;8(3):036023. doi: 10.1088/1741-2560/8/3/036023. Epub 2011 May 11.
The selection of a suitable nerve electrode for neuroprosthetic applications implies a trade-off between invasiveness and selectivity, wherein the ultimate goal is achieving the highest selectivity for a high number of nerve fascicles by the least invasiveness and potential damage to the nerve. The transverse intrafascicular multichannel electrode (TIME) is intended to be transversally inserted into the peripheral nerve and to be useful to selectively activate subsets of axons in different fascicles within the same nerve. We present a comparative study of TIME, LIFE and multipolar cuff electrodes for the selective stimulation of small nerves. The electrodes were implanted on the rat sciatic nerve, and the activation of gastrocnemius, plantar and tibialis anterior muscles was recorded by EMG signals. Thus, the study allowed us to ascertain the selectivity of stimulation at the interfascicular and also at the intrafascicular level. The results of this study indicate that (1) intrafascicular electrodes (LIFE and TIME) provide excitation circumscribed to the implanted fascicle, whereas extraneural electrodes (cuffs) predominantly excite nerve fascicles located superficially; (2) the minimum threshold for muscle activation with TIME and LIFE was significantly lower than with cuff electrodes; (3) TIME allowed us to selectively activate the three tested muscles when stimulating through different active sites of one device, both at inter- and intrafascicular levels, whereas selective activation using multipolar cuff (with a longitudinal tripolar stimulation configuration) was only possible for two muscles, at the interfascicular level, and LIFE did not activate selectively more than one muscle in the implanted nerve fascicle.
用于神经假体应用的合适神经电极的选择意味着在侵入性和选择性之间进行权衡，其中最终目标是通过最小的侵入性和对神经的潜在损伤，实现对大量神经纤维束的最高选择性。横向纤维内多通道电极（TIME）旨在横向插入外周神经，并可用于选择性地激活同一神经内不同纤维束中的轴突亚群。我们对 TIME、LIFE 和多极袖套电极进行了比较研究，以选择性刺激小神经。将电极植入大鼠坐骨神经上，并通过肌电图信号记录比目鱼肌、足底和胫骨前肌的激活情况。因此，该研究使我们能够确定在纤维间和纤维内水平的刺激选择性。这项研究的结果表明：（1）纤维内电极（LIFE 和 TIME）提供局限于植入纤维束的兴奋，而神经外电极（袖套）主要兴奋位于表面的神经纤维束；（2）使用 TIME 和 LIFE 进行肌肉激活的最小阈值明显低于袖套电极；（3）当通过一个装置的不同活动部位进行刺激时，TIME 可让我们在纤维间和纤维内水平选择性地激活三个测试肌肉，而使用多极袖套（采用纵向三极刺激配置）进行选择性激活仅适用于两个肌肉，在纤维间水平，而 LIFE 不能选择性地激活植入神经纤维束中的超过一个肌肉。
