In vivo comparison of the charge densities required to evoke motor responses using novel annular penetrating microelectrodes.
In vivo comparison of the charge densities required to evoke motor responses using novel annular penetrating microelectrodes.
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DOI：
10.3389/fnins.2015.00265
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发表时间：
2015
影响因子：
4.3
通讯作者：
Rajan R
中科院分区：
文献类型：
--
作者：
Brunton EK;Winther-Jensen B;Wang C;Yan EB;Hagh Gooie S;Lowery AJ;Rajan R
用于皮层刺激的电极需要有效且安全地向神经组织输送电流。我们已经开发出一种新的环形几何电极用于皮质视觉假体。在这里，我们探讨了一个关键问题，即理想的瓣环高度，以确保电刺激安全有效。我们将单个电极植入麻醉大鼠的运动皮层，并测量引起对刺激的运动反应所需的电流，以及电极的电荷注入能力（CIC）。我们比较了具有不同环高度的铂铱（PtIr）电极，有和没有多孔氮化钛（TiN）涂层。诱发运动反应的阈值电荷密度范围为12至36 μC.cm-2.ph-1。具有较大几何表面积（GSA）的电极需要较高的电流来引起响应，但电荷密度较低。添加多孔TiN涂层不会显著影响引起运动反应所需的电流。与体外测量相比，两种电极类型的CIC在体内显著降低。对于有TiN涂层和没有TiN涂层的电极，测得的CIC分别为72和18 μC.cm-2.ph-1。这些结果支持使用环高度大于100 μm（GSA为38，000 μm2）的PtIr环形电极。然而，如果电极涂覆有多孔TiN，则环高度可以减小到40 μm（GSA为16，000 μm2）。
Electrodes for cortical stimulation need to deliver current to neural tissue effectively and safely. We have developed electrodes with a novel annular geometry for use in cortical visual prostheses. Here, we explore a critical question on the ideal annulus height to ensure electrical stimulation will be safe and effective. We implanted single electrodes into the motor cortex of anesthetized rats and measured the current required to evoke a motor response to stimulation, and the charge injection capacity (CIC) of the electrodes. We compared platinum iridium (PtIr) electrodes with different annulus heights, with and without a coating of porous titanium nitride (TiN). Threshold charge densities to evoke a motor response ranged from 12 to 36 μC.cm-2.ph-1. Electrodes with larger geometric surface areas (GSAs) required higher currents to evoke responses, but lower charge densities. The addition of a porous TiN coating did not significantly influence the current required to evoke a motor response. The CIC of both electrode types was significantly reduced in vivo compared with in vitro measurements. The measured CIC was 72 and 18 μC.cm-2.ph-1 for electrodes with and without a TiN coating, respectively. These results support the use of PtIr annular electrodes with annulus heights greater than 100 μm (GSA of 38, 000 μm2). However, if the electrodes are coated with porous TiN the annulus height can be reduced to 40 μm (GSA of 16,000 μm2).