Auditory cortical images of cochlear-implant stimuli: Dependence on electrode configuration
Auditory cortical images of cochlear-implant stimuli: Dependence on electrode configuration
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DOI：
10.1152/jn.00212.2001
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发表时间：
2002-01-01
影响因子：
2.5
通讯作者：
Middlebrooks, JC
中科院分区：
文献类型：
--
作者：
Bierer, JA;Middlebrooks, JC
本研究探讨了单脉冲人工耳蜗刺激引起的听觉皮层活动的模式，这些刺激在电极配置、耳蜗刺激位置和刺激水平上各不相同。从氯胺酮麻醉的豚鼠的初级听觉皮层（A1区）进行记录。神经锋电位活动的时空模式，同时测量跨越约2-3个八度的tonotopic轴的16个皮层位置。这样的模式，平均超过40个介绍的任何特定的刺激，被定义为“皮质图像”的刺激。将6电极动物版的22电极Nucleus带状电极阵列（Coatriar）植入急性中毒豚鼠。同轴电极配置包括单极（MP）、双极（BP + N）（有源电极和回流电极之间有N个非有源电极）（0小于或等于N小于或等于4）、三极（TP）（有一个有源电极和两个侧翼回流电极）和公共接地（CG）（有一个有源电极和多达五个回流电极）。皮质图像通常显示最大尖峰概率和最小延迟的焦点。尖峰概率趋于减少，而lavonian趋于增加，随着皮层距离该焦点。TP刺激的皮层图像空间最紧凑，其次是BP + N图像，然后是MP图像，这是最广泛的。CG刺激的图像在动物和刺激通道之间是相当可变的。随着耳蜗刺激位置从基底部向顶部的改变，皮层图像的位置系统地从尾侧向喙侧转移。在每种条件下最敏感的皮质部位，尖峰频率随电流水平增加而增加的动态范围被限制在约1-2 dB，无论配置如何。动态范围往往会增加与最敏感的网站增加皮质距离。产生紧凑皮层图像的电极配置（例如，TP和BP + 0）在每个皮层图像内显示出最大的阈值范围，并且在从最敏感部位移除的皮层部位处显示出最大的动态范围。
This study examines patterns of auditory cortical activity elicited by single-pulse cochlear implant stimuli that vary in electrode configuration, cochlear place of stimulation, and stimulus level. Recordings were made from the primary auditory cortex (area A1) of ketamine-anesthetized guinea pigs. The spatiotemporal pattern of neural spike activity was measured simultaneously across 16 cortical locations spanning approximately 2-3 octaves of the tonotopic axis. Such a pattern, averaged over 40 presentations of any particular stimulus, was defined as the "cortical image" of that stimulus. Acutely deafened guinea pigs were implanted with a 6-electrode animal version of the 22-electrode Nucleus banded electrode array (Cochlear). Cochlear electrode configurations consisted of monopolar (MP), bipolar (BP + N) with N inactive electrodes between the active and return electrodes (0 less than or equal to N less than or equal to 4), tripolar (TP) with one active electrode and two flanking return electrodes, and common ground (CG) with one active electrode and as many as five return electrodes. Cortical images typically showed a focus of maximum spike probability and minimum latency. Spike probabilities tended to decrease, and latencies tended to increase, with increasing cortical distance from that focus. Cortical images of TP stimuli were the most spatially compact, followed by BP + N images, and then MP images, which were the broadest. Images of CG stimuli were rather variable across animals and stimulus channels. The locations of cortical images shifted systematically from caudal to rostral as the cochlear place of stimulation changed from basal to apical. At the most sensitive cortical site for each condition, the dynamic ranges over which spike rates increased with increased current level were restricted to about 1-2 dB, regardless of configuration. Dynamic ranges tended to increase with increasing cortical distance from the most sensitive site. Electrode configurations that produced compact cortical images (e.g., TP and BP + 0) showed the greatest range of thresholds within each cortical image and the largest dynamic range at cortical sites removed from the most sensitive site.