Department of Biomedical Engineering, University of Utah, 36 S Wasatch Dr, Salt Lake City, UT 84112, United States of America.
Department of Chemical Engineering, Herbert Wertheim College of Engineering, University of Florida, 1030 Center Drive PO Box, Gainesville, FL 116005, United States of America.
J Neural Eng. 2024 Jun 27;21(3). doi: 10.1088/1741-2552/ad5703.
Electrodes chronically implanted in the brain undergo complex changes over time that can lower the signal to noise ratio (SNR) of recorded signals and reduce the amount of energy delivered to the tissue during therapeutic stimulation, both of which are relevant for the development of robust, closed-loop control systems. Several factors have been identified that link changes in the electrode-tissue interface (ETI) to increased impedance and degraded performance in micro- and macro-electrodes. Previous studies have demonstrated that brief pulses applied every few days can restore SNR to near baseline levels during microelectrode recordings in rodents, a process referred to as electrical rejuvenation. However, electrical rejuvenation has not been tested in clinically relevant macroelectrode designs in large animal models, which could serve as preliminary data for translation of this technique. Here, several variations of this approach were tested to characterize parameters for optimization.. Alternating-current (AC) and direct-current (DC) electrical rejuvenation methods were explored in three electrode types, chronically implanted in two adult male nonhuman primates (NHP) (), which included epidural electrocorticography (ECoG) electrodes and penetrating deep-brain stimulation (DBS) electrodes. Electrochemical impedance spectroscopy (EIS) was performed before and after each rejuvenation paradigm as a gold standard measure of impedance, as well as at subsequent intervals to longitudinally track the evolution of the ETI. Stochastic error modeling was performed to assess the standard deviation of the impedance data, and consistency with the Kramers-Kronig relations was assessed to evaluate the stationarity of EIS measurement.. AC and DC rejuvenation were found to quickly reduce impedance and minimize the tissue component of the ETI on all three electrode types, with DC and low-frequency AC producing the largest impedance drops and reduction of the tissue component in Nyquist plots. The effects of a single rejuvenation session were found to last from several days to over 1 week, and all rejuvenation pulses induced no observable changes to the animals' behavior.. These results demonstrate the effectiveness of electrical rejuvenation for diminishing the impact of chronic ETI changes in NHP with clinically relevant macroelectrode designs.
长期植入大脑的电极会随着时间的推移发生复杂的变化，从而降低记录信号的信噪比（SNR）并减少治疗刺激期间传递到组织的能量，这两者对于开发强大的闭环控制系统都很重要。已经确定了一些因素，这些因素将电极 - 组织界面（ETI）的变化与微电极和宏观电极中的阻抗增加和性能下降联系起来。先前的研究表明，在啮齿动物的微电极记录中，每隔几天施加短脉冲可以将 SNR 恢复到接近基线水平，这一过程称为电复兴。然而，电复兴尚未在大型动物模型的临床相关宏观电极设计中进行测试，这可以作为该技术转化的初步数据。在这里，测试了几种这种方法的变体来表征优化参数。在三种电极类型中探索了交流（AC）和直流（DC）电复兴方法，这些电极长期植入两名成年雄性非人类灵长类动物（NHP）（）中，包括硬膜外脑电描记术（ECoG）电极和穿透性深部脑刺激（DBS）电极。电化学阻抗谱（EIS）在每次复兴范例之前和之后进行，作为阻抗的金标准测量，以及在随后的间隔内进行，以纵向跟踪 ETI 的演变。随机误差建模用于评估阻抗数据的标准偏差，并评估与 Kramer-Kronig 关系的一致性，以评估 EIS 测量的稳定性。发现 AC 和 DC 复兴可快速降低阻抗并最小化所有三种电极类型的 ETI 的组织分量，其中 DC 和低频 AC 产生最大的阻抗下降和奈奎斯特图中组织分量的减少。单次复兴疗程的效果被发现可持续数天至 1 周以上，并且所有复兴脉冲都不会引起动物行为的可观察变化。这些结果表明，电复兴对于减轻 NHP 中与临床相关的宏观电极设计中慢性 ETI 变化的影响是有效的。
