INTERAURAL PHASE-SENSITIVE UNITS IN THE INFERIOR COLLICULUS OF THE UNANESTHETIZED RABBIT - EFFECTS OF CHANGING FREQUENCY
INTERAURAL PHASE-SENSITIVE UNITS IN THE INFERIOR COLLICULUS OF THE UNANESTHETIZED RABBIT - EFFECTS OF CHANGING FREQUENCY
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DOI：
10.1152/jn.1987.57.5.1338
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发表时间：
1987-05-01
影响因子：
2.5
通讯作者：
BATRA, R
中科院分区：
文献类型：
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作者：
KUWADA, S;STANFORD, TR;BATRA, R
我们研究了未麻醉兔子下丘 (IC) 85 个单位的耳间相位敏感性。我们在每个单元的响应范围内的几个频率上评估了这种灵敏度。通过向两只耳朵传送相差 1 Hz 的音调来改变耳间相位差，从而产生 1 Hz 的双耳节拍。我们通过计算四个指标来分析每个单元对不同频率的响应：特征延迟（CD）、特征相位（CP）、复合峰值延迟和平均峰值延迟。我们分别根据拟合平均耳间相位与刺激频率图的回归线的斜率和相位截距来估计 CD 和 CP。复合峰值延迟是根据复合延迟曲线的峰值来估计的。这是通过重新绘制对耳间相位变化的响应作为等效耳间延迟的函数并对所得耳间延迟曲线进行平均而生成的。复合延迟曲线反映了设备对不同频率的耳间延迟的平均响应。最后，我们计算了平均峰值延迟，该延迟是通过将每个频率下响应的平均耳间相位转换为等效延迟，然后对这些延迟求平均值而得出的。观察到频率高达 2,150 Hz 的耳间相位敏感性。然而，大多数设备在 1,500 Hz 以下都表现出这种灵敏度。对于大多数设备，在多个频率下测量的耳间延迟曲线在峰值放电附近重合。这一结果与神经模型一致，其中来自每只耳朵的兴奋性输入汇聚到双耳细胞上，仅当两个输入同时到达时才会引起最大放电。作为第一个近似值，我们的数据符合这个模型，表明 IC 神经元可以像重合检测器或互相关器一样起作用。 CD、复合峰值延迟和平均峰值延迟的分布表明，大多数单位更喜欢同侧刺激延迟，这在自然情况下对应于从对侧场发出的声音。此外，大多数单位更喜欢在兔子的估计生理范围内的延迟。这些结果支持 IC 中的神经元参与声音定位的观点。 CP 和 CD 的分布与麻醉猫 IC 中发现的分布有很大不同。这些差异可能反映了物种差异、麻醉效果或抽样单位群体的差异。对于每个单元，我们使用 chi 2 方法评估了平均耳间相位与刺激频率的关系图的线性度。对于大多数单位来说，绘图明显是非线性的。（摘要截断为 400 字）
We studied the interaural phase sensitivity of 85 units in the inferior colliculus (IC) of the unanesthetized rabbit. We assessed this sensitivity at several frequencies within each unit's responsive range. The interaural phase disparity was varied by delivering tones that differed by 1 Hz to the two ears, resulting in a 1-Hz binaural beat. We analyzed each unit's response to different frequencies by calculating four measures: characteristic delay (CD), characteristic phase (CP), composite peak delay, and mean peak delay. We estimated the CD and CP from the slope and phase intercept, respectively, of the regression line fitted to a plot of the mean interaural phase against stimulating frequency. The composite peak delay was estimated from the peak of a composite delay curve. This was generated by replotting the response to changes in interaural phase, as a function of the equivalent interaural delay and averaging the resultant interaural delay curves. The composite delay curve reflects the unit's average response to interaural delays across frequencies. Last, we calculated a mean peak delay, derived by converting the mean interaural phase of the response at each frequency to an equivalent delay and then averaging these delays. Interaural phase sensitivity was observed to frequencies as high as 2,150 Hz. However, the majority of units showed such sensitivity below 1,500 Hz. For most units, the interaural delay curves measured at several frequencies coincided near the peak discharge. This result is consistent with a neural model, where excitatory inputs from each ear converge upon a binaural cell, evoking maximum discharge only when the two inputs arrive simultaneously. As a first approximation, our data fit this model, indicating that IC neurons can act like coincidence detectors or cross-correlators. The distributions of CD, composite peak delay, and mean peak delay showed that most units preferred ipsilateral stimulus delays, which in the natural situation corresponds to sounds emanating from the contralateral field. Moreover, most units preferred delays that were within the estimated physiological range of the rabbit. These results support the viewpoint that neurons in the IC participate in sound localization. The distributions of CP and CD differ substantially from those found in the IC of the anesthetized cat. These differences may reflect species differences, the effects of anesthesia, or a difference in the population of units sampled. For each unit, we assessed the linearity of the plot of mean interaural phase against frequency of stimulation using a chi 2 method. For most units the plots were significantly nonlinear.(ABSTRACT TRUNCATED AT 400 WORDS)