Binaural inhibition is important in shaping the free-field frequency selectivity of single neurons in the inferior colliculus
Binaural inhibition is important in shaping the free-field frequency selectivity of single neurons in the inferior colliculus
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DOI：
10.1152/jn.1996.76.4.2580
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发表时间：
1996-10-01
影响因子：
2.5
通讯作者：
Feng, AS
中科院分区：
文献类型：
--
作者：
Gooler, DM;Xu, JH;Feng, AS
1. 我们之前已经证明，在额叶野的自由场刺激下，当扬声器移到同侧方位角时，大多数下丘（IC）神经元的频率选择性变得更强。这些结果表明，双耳抑制可能是频率选择性方向依赖性锐化的原因。为了直接验证上述假设，我们研究了IC神经元在几种条件下的频率选择性：使用半封闭的声学刺激系统的单耳刺激，使用半封闭系统的双耳二元刺激，不同方位的自由场刺激，以及当单侧耳朵被封闭时的自由场刺激（涂上一层厚厚的凡士林，有效地减弱了这只耳朵的声输入）。研究了北纹蛙（Rana pipiens pipiens） 98个IC神经元的双耳相互作用模式；其中，EE神经元34个，EO神经元64个。大多数IC神经元（98个中的92个）表现出一定程度的双耳抑制（即，当同侧和对侧耳朵同时受到刺激时，反应减弱），无论它们被指定为EE或EO；这些IC神经元因此被分类为EE-I或EO-I。如果ILD功能表现出明显的反应下降，即对侧耳单耳刺激反应的下降大于或等于50%，则神经元被归类为表现出强抑制。这些神经元表现出较小的反应下降(下降大于或等于25%，但
1. We have shown previously that under free-field stimulation in the frontal field, frequency selectivity of the majority of inferior colliculus (IC) neurons became sharper when the loudspeaker was shifted to ipsilateral azimuths. These results indicated that binaural inhibition may be responsible for the direction-dependent sharpening of frequency selectivity. To test the above hypothesis directly, we investigated the frequency selectivity of IC neurons under several conditions: monaural stimulation using a semiclosed acoustical stimulation system, binaural stimulation dichotically also using a semiclosed system, free-field stimulation from different azimuths, and free-field stimulation when the ipsilateral ear was occluded monaurally (coated with a thick layer of petroleum jelly, which effectively attenuated acoustic input to this ear).2. The binaural interaction pattern of 98 IC neurons of northern leopard frogs (Rana pipiens pipiens) were evaluated; of these neurons, there were 34 EE and 64 EO neurons. The majority of IC neurons (92 of 98) showed some degree of binaural inhibition (i.e., showing diminished response when the ipsilateral and contralateral ears were stimulated simultaneously) whether they were designated as EE or EO; these IC neurons thus were classified as EE-I or EO-I. Neurons were classified as exhibiting strong inhibition if the ILD function showed a pronounced response decrement, i.e., a decrease of greater than or equal to 50% of the response to monaural stimulation of the contralateral ear. Those neurons that showed smaller response decrements (decrease was greater than or equal to 25% but