Significance: Cortically implanted microelectrode arrays provide a direct interface with neuronal populations and are used to restore movement capabilities and provide sensory feedback to patients with paralysis or amputation. Penetrating electrodes experience high rates of signal degradation within the first year that limit effectiveness and lead to eventual device failure. Aim: To assess vascular and neuronal changes over time in mice with implanted electrodes and examine the contribution of the brain tissue response to electrode performance. Approach: We used a multimodal approach combining in vivo electrophysiology and subcellular-level optical imaging. Results: At acute timescales, we observed structural damage from the mechanical trauma of electrode insertion, evidenced by severed dendrites in the electrode path and local hypofluorescence. Superficial vessel growth and remodeling occurred within the first few weeks in both electrode-implanted and window-only animals, but the deeper capillary growth evident in window-only animals was suppressed in electrode-implanted animals. After longer implantation periods, there was evidence of degeneration of transected dendrites superficial to the electrode path and localized neuronal cell body loss, along with deep vascular velocity changes near the electrode. Total spike rate (SR) across all animals reached a peak between 3 and 9 months postimplantation, then decreased. The local field potential signal remained relatively constant for up to 6 months, particularly in the high-gamma band, indicating long-term electrode viability and neuronal functioning at further distances from the electrode, but it showed a reduction in some animals at later time points. Most importantly, we found that progressive high-gamma and SR reductions both correlate positively with localized cell loss and decreasing capillary density within 100    μ m of the electrode. Conclusions: This multifaceted approach provided a more comprehensive picture of the ongoing biological response at the brain-electrode interface than can be achieved with postmortem histology alone and established a real-time relationship between electrophysiology and tissue damage.

中文翻译：

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纵向变性多模式评估神经变性和血管重塑与慢性皮质硅微电极信号降解相关。

启示：皮层植入的微电极阵列提供了与神经元群体的直接接口，并用于恢复运动能力并向麻痹或截肢患者提供感觉反馈。穿透电极在第一年内会经历很高的信号衰减率，这限制了有效性并导致最终的设备故障。目的：评估植入电极的小鼠随时间变化的血管和神经元变化，并检查脑组织响应对电极性能的影响。方法：我们采用了一种结合体内电生理学和亚细胞水平光学成像的多峰方法。结果：在急性时间尺度上，我们观察到电极插入的机械损伤引起的结构破坏，这由电极路径中的树枝状断裂和局部低荧光证实。在植入电极的和仅开窗的动物中，在最初的几周内发生了表浅的血管生长和重塑，但是在植入电极的动物中，在仅开窗的动物中明显的更深的毛细血管生长受到抑制。在更长的植入期后，有证据表明，横切的树突在电极路径表面变性，局部神经元细胞体丢失，同时电极附近的血管深度也发生了变化。所有动物的总刺突率（SR）在植入后3至9个月达到峰值，然后下降。局部电场电势信号在长达6个月的时间内保持相对恒定，尤其是在高伽玛谱带中，这表明电极的长期生存能力和距电极更远的神经元功能，但在随后的时间点上，某些动物的数量减少了。最重要的是，我们发现，逐步的高伽玛系数和SR降低均与局部细胞损失和电极100μm内的毛细管密度降低呈正相关。结论：这种多方面的方法提供了比仅使用死后组织学所能获得的更全面的图像，说明了在脑电极界面上正在进行的生物学反应，并建立了电生理与组织损伤之间的实时关系。