Kidd S A, Kelly J B
Laboratory of Sensory Neuroscience, Carleton University, Ottawa, Ontario, Canada.
J Neurosci. 1996 Nov 15;16(22):7390-7. doi: 10.1523/JNEUROSCI.16-22-07390.1996.
The contribution of the dorsal nucleus of the lateral lemniscus (DNLL) to binaural responses in the inferior colliculus of the rat was determined for a wide range of interaural time differences (ITDs). Single-unit action potentials were recorded from the inferior colliculus before and after local injection of the excitatory amino acid antagonist kynurenic acid into the DNLL. Binaural properties were determined by manipulating the time difference between paired clicks delivered to the ears ipsilateral and contralateral to the recording site. The probability of an action potential decreased as contralateral stimulation was delayed, relative to ipsilateral stimulation. These data generated a sigmoidal ITD curve for delays between -1.0 and + 1.0 msec. By extending the time intervals beyond 1 msec, it was possible to determine the trailing edge of the inhibition produced by ipsilateral stimulation. The duration of the inhibitory effect varied from cell to cell but lasted as long as 20 msec in some cases. Injection of kynurenic acid into the DNLL contralateral to the recording site reduced the extent of both short (0-1 msec) and long-lasting (1-20 msec) inhibition in the inferior colliculus. No effect was seen after injections ipsilateral to the recording site. The data demonstrate that the DNLL plays an important role in shaping ITD responses in the inferior colliculus and contributes to both the short and long-lasting inhibition produced by stimulation of the ipsilateral ear.
在广泛的双耳时间差（ITD）范围内，确定了大鼠下丘中外侧丘系背核（DNLL）对双耳反应的贡献。在向DNLL局部注射兴奋性氨基酸拮抗剂犬尿氨酸之前和之后，记录下丘的单单位动作电位。通过操纵传递到记录部位同侧和对侧耳朵的配对点击之间的时间差来确定双耳特性。相对于同侧刺激，随着对侧刺激延迟，动作电位的概率降低。这些数据生成了一个-1.0至+1.0毫秒延迟的S形ITD曲线。通过将时间间隔延长至1毫秒以上，可以确定同侧刺激产生的抑制的后沿。抑制作用的持续时间因细胞而异，但在某些情况下长达20毫秒。向记录部位对侧的DNLL注射犬尿氨酸可减少下丘中短期（0-1毫秒）和长期（1-20毫秒）抑制的程度。在记录部位同侧注射后未观察到效果。数据表明，DNLL在塑造下丘的ITD反应中起重要作用，并对同侧耳刺激产生的短期和长期抑制都有贡献。
