STIMULUS PARAMETERS AFFECTING TISSUE-INJURY DURING MICROSTIMULATION IN THE COCHLEAR NUCLEUS OF THE CAT
STIMULUS PARAMETERS AFFECTING TISSUE-INJURY DURING MICROSTIMULATION IN THE COCHLEAR NUCLEUS OF THE CAT
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DOI：
10.1016/0378-5955(94)90258-5
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发表时间：
1994-06-15
期刊：
影响因子：
2.8
通讯作者：
BULLARA, LA
中科院分区：
文献类型：
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作者：
MCCREERY, DB;YUEN, TGH;BULLARA, LA
我们使用长期植入的激活铱微电极，研究了持续微刺激对猫后腹侧耳蜗核的影响。我们检查了51个电极位点（39个脉冲位点和12个非脉冲位点）。连续7小时的500赫兹刺激通常会造成脉冲微电极尖端附近的组织损伤。损伤以液泡组织区域的形式从电极尖端延伸200 μ m或更多。电镜观察显示，液泡是髓鞘轴突严重水肿的节段。损伤组织的数量与每相电荷量之间存在较大且极显著的统计学相关性（P < 0.0001）。当电极在500 Hz下以电荷平衡双相脉冲对脉冲7 h时，损伤阈值约为3 nC/相。当增产时间延长至35小时（每天7小时，持续5天）时，损伤阈值并没有明显降低。相比之下，微电极附近激发神经元的阈值约为1 nC/相，这是由下丘记录的诱发反应确定的。组织损伤的严重程度与电极表面的几何电荷密度之间、损伤程度与刺激电流脉冲在刺激电极上引起的电压瞬态的阴极相位幅值之间、损伤程度与刺激脉冲持续时间之间的相关性不大。
We investigated the effects of continuous microstimulation in the cats' posteroventral cochlear nucleus, using chronically implanted activated iridium microelectrodes. We examined 51 electrode sites (39 pulsed sites, and 12 unpulsed sites). Seven hours of continuous stimulation at 500 Hz often produced tissue injury near the tips of the pulsed microelectrodes. The damage took the form of a region of vacuolated tissue extending 200 mu m or more from the site of the electrode tip. Electron microscope studies showed the vacuoles to be severely edematous segments of myelinated axons. The statistical correlation between the amount of damaged tissue and the charge per phase was large and highly significant (P < 0.0001). When the electrodes were pulsed for 7 h at 500 Hz with charge-balanced biphasic pulse pairs, the threshold for the damage was approximately 3 nC/phase. The damage threshold was not appreciably lower when the stimulation protocol was extended to 35 h (7 h/day for 5 days). in contrast, the threshold for exciting neurons near the microelectrode is approximately 1 nC/phase, as determined by the evoked response recorded in the inferior colliculus. There was little correlation between the severity of the tissue damage and the geometric charge density at the surface of the electrodes, between the damage and amplitude of the cathodic phase of the voltage transient induced across the stimulating electrodes by the stimulus current pulses, or between the damage and the stimulus pulse duration.