Responses of neurons in inferior colliculus to variations in sound-source azimuth.
Responses of neurons in inferior colliculus to variations in sound-source azimuth.
复制标题
下丘神经元对声源方位角变化的反应。
DOI：
10.1152/jn.1984.52.1.1
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发表时间：
1984
影响因子：
2.5
通讯作者：
S. Phillips
中科院分区：
文献类型：
--
作者：
L. Aitkin;G. Gates;S. Phillips
这项研究的目的是对听觉中脑中单个单元对自由场中出现的声刺激的反应进行分类，以便表征那些可能在水平面声音定位中发挥作用的单元。研究人员使用能够在水平面以上 10 度平面上的任意点移动的扬声器发出的音调和噪声刺激来研究猫和刷尾负鼠下丘中 131 个单个单元的反应。扬声器沿该平面的位置称为扬声器方位角；与记录的下丘同侧的方位角为同侧，与记录的下丘相反的一侧的方位角为对侧。对于每个单元，尖峰计数作为方位角的函数在最佳频率 (BF) 或使用噪声突发进行测量。这些函数称为方位角函数，通常测量至少两个强度（高于阈值 10 到 70 dB 之间）。大多数单元的记录位点在组织学上借助微损伤进行识别，并且与下丘的主要细分相关：中央核（ICC）、外核外侧部分（ICX）和口腹突（R-ICX）。两个单位位于中央周围核，两个单位位于外侧丘系的背核。确定了两大类神经元：全向神经元和方向敏感神经元。全向单元表现出的方位角函数要么平坦，要么在同侧方位角逐渐下降。对于后面的单位，所有点的放电率随着刺激强度单调增加。对于这两种类型的全向单元，没有迹象表明存在显着的双耳交互。在双耳分离研究中观察到的兴奋性-兴奋性 (EE) 和单耳 (EO) 单元的总比例 (46-55%) 与本研究中的全向单元的比例 (47%) 之间存在良好的相关性。方向敏感单元的子组（占总数的 36%）显示了方位角函数，其中放电边界的方位角位置或峰值发射方位角在刺激强度范围内基本保持不变。这些方位选择性单元可能在水平面刺激位置的检测中发挥作用，并且似乎包括在二分研究中被认为是兴奋抑制（EI）或延迟敏感的单元。方向敏感单元表现出显着方向效应的方位角受到对侧耳廓位置的影响。（摘要截断为 400 字）
This study aimed to classify the responses of single units in the auditory midbrain to acoustic stimuli presented in the free field in order to characterize those units likely to have a role in sound localization in the horizontal plane. The responses of 131 single units in the inferior colliculus of the cat and the brush-tailed possum were studied using tone and noise-burst stimuli presented from a speaker capable of movement at any point along a plane 10 degrees above the horizontal plane. Speaker positions along this plane are referred to as speaker azimuths; those on the same side as the recorded inferior colliculus as ipsilateral, and on the opposite side as contralateral, azimuths. For each unit, spike counts were measured as a function of azimuth either at the best frequency (BF) or using noise bursts. These functions are referred to as azimuth functions and were usually measured for at least two intensities, between 10 and 70 dB above threshold. The recording sites of most units were identified histologically with the aid of microlesions and were related to the major subdivisions of the inferior colliculus: the central nucleus (ICC), the lateral part of the external nucleus (ICX), and the rostroventral process (R-ICX). Two units were located in the pericentral nucleus and two in the dorsal nucleus of the lateral lemniscus. Two major classes of neuron were identified: omnidirectional and directionally sensitive. Omnidirectional units exhibited azimuth functions that were either flat or that declined gradually at progressively ipsilateral azimuths. For the latter units, discharge rates at all points monotonically increased with stimulus intensity. There was no indication, for either type of omnidirectional unit, of significant binaural interaction. A good correlation was found between the summed proportions of excitatory-excitatory (EE) and monaural (EO) units observed in dichotic studies (46-55%) and the proportion of omnidirectional units in the present study (47%). A subgroup of directionally sensitive units (36% of the total) displayed azimuth functions for which the azimuthal position of the discharge border or peak firing azimuth remained essentially unaltered over a range of stimulus intensities. These azimuth-selective units are likely to have a role in the detection of the location of stimuli in the horizontal plane and appear to include units that would be considered excitatory-inhibitory (EI) or delay sensitive in dichotic studies. The azimuths over which directionally sensitive units showed their marked directional effects were influenced by the position of the contralateral pinna.(ABSTRACT TRUNCATED AT 400 WORDS)