Chronic recruitment of primary afferent neurons by microstimulation in the feline dorsal root ganglia
Chronic recruitment of primary afferent neurons by microstimulation in the feline dorsal root ganglia
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DOI：
10.1088/1741-2560/11/3/036007
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发表时间：
2014-06-01
影响因子：
4
通讯作者：
Gaunt, Robert A.
中科院分区：
文献类型：
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作者：
Fisher, Lee E.;Ayers, Christopher A.;Gaunt, Robert A.
目标。本研究描述了在四只猫的腰椎背根神经节(DRG)内长期植入微电极阵列进行初级传入神经微刺激实验的结果。目的是测试这些微电极阵列的稳定性和选择性，作为神经系统损伤(如截肢)后恢复体感反馈的潜在接口。接近。用植入坐骨神经的五接触神经袖带电极记录背根神经节微刺激(2~15mA双相脉冲，200mU S阴极脉宽)的逆行复合动作电位反应，并随时间追踪诱发反应的阈值。记录的反应根据传导速度进行分离，以确定招募I组和II/A组B组初级传入纤维的阈值。主要结果。阈值最初很低(第一组为5.1+/-2.3亩A，第二组/A测试组为6.3+/-2.0亩A)，并随着时间的推移而增加。此外，阈值小于或等于15微安的电极数量随着时间的推移而减少。大约12%的被测电极在植入后的26周内仍能在15微安下产生反应。一只猫在植入后23周测试了更高的刺激强度(高达30mA)，在20多个额外的电极上产生了反应。在植入后的前6周内，大致相同数量的电极仅在阈值时引起第I组或第II/A组的β反应，但随着时间的推移，第II/A组的β反应的相对比例下降。意义重大。这些结果表明，通过植入背根节的穿透性微电极阵列，可以单独激活I组或II/A组Beta组初级传入纤维，这些反应可以在植入后26周内激发，尽管目前可用的电极技术可能很难实现日常一致的反应。DRG是感觉神经假体的极具吸引力的靶点，有可能在植入后数月内实现一系列感觉纤维类型的招募。
Objective. This study describes results of primary afferent neural microstimulation experiments using microelectrode arrays implanted chronically in the lumbar dorsal root ganglia (DRG) of four cats. The goal was to test the stability and selectivity of these microelectrode arrays as a potential interface for restoration of somatosensory feedback after damage to the nervous system such as amputation. Approach. A five-contact nerve-cuff electrode implanted on the sciatic nerve was used to record the antidromic compound action potential response to DRG microstimulation (2-15 mu A biphasic pulses, 200 mu s cathodal pulse width), and the threshold for eliciting a response was tracked over time. Recorded responses were segregated based on conduction velocity to determine thresholds for recruiting Group I and Group II/A beta primary afferent fibers. Main results. Thresholds were initially low (5.1 +/- 2.3 mu A for Group I and 6.3 +/- 2.0 mu A for Group II/A beta) and increased over time. Additionally the number of electrodes with thresholds less than or equal to 15 mu A decreased over time. Approximately 12% of tested electrodes continued to elicit responses at 15 mu A up to 26 weeks after implantation. Higher stimulation intensities (up to 30 mu A) were tested in one cat at 23 weeks post-implantation yielding responses on over 20 additional electrodes. Within the first six weeks after implantation, approximately equal numbers of electrodes elicited only Group I or Group II/A beta responses at threshold, but the relative proportion of Group II/A beta responses decreased over time. Significance. These results suggest that it is possible to activate Group I or Group II/A beta primary afferent fibers in isolation with penetrating microelectrode arrays implanted in the DRG, and that those responses can be elicited up to 26 weeks after implantation, although it may be difficult to achieve a consistent response day-to-day with currently available electrode technology. The DRG are compelling targets for sensory neuroprostheses with potential to achieve recruitment of a range of sensory fiber types over multiple months after implantation.