Early appearance of inhibitory input to the MNTB supports binaural processing during development
Early appearance of inhibitory input to the MNTB supports binaural processing during development
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DOI：
10.1152/jn.00601.2005
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发表时间：
2005-12-01
影响因子：
2.5
通讯作者：
Sanes, DH
中科院分区：
文献类型：
--
作者：
Green, JS;Sanes, DH
尽管外围和中枢的不成熟限制了幼年动物的听觉处理，但它们能够利用双耳线索来偏向声音。这项研究探索了一种可以弥补开发过程中这些限制的核心机制。上橄榄复合体神经元的耳间时间和声级差异处理取决于梯形体内侧核 (MNTB) 的突触抑制，梯形体内侧核是一组由对侧声音刺激激活的抑制性神经元。在这项研究中，我们检查了 MNTB 神经元编码特性的成熟情况，发现它们受到同侧耳朵的抑制影响，这种影响在出生后发育过程中发生了改变。单神经元记录是从幼年沙鼠（出生后 15-19 天）和成年沙鼠的 MNTB 中获得的。所有记录的 MNTB 神经元中大约 50% 受到同侧声音刺激的抑制，但与成人相比，幼年神经元表现出更大的放电抑制。前电位和突触后动作电位的比较表明抑制发生在突触前水平，可能发生在耳蜗核内。接收 MNTB 输入的外侧上橄榄神经元的水平差异检测的简单线性模型表明，抑制 MNTB 可能会扩大 LSO 神经元对生理上实际水平差异的反应，特别是在幼年动物中，当这些线索减少时。
Despite the peripheral and central immaturities that limit auditory processing in juvenile animals, they are able to lateralize sounds using binaural cues. This study explores a central mechanism that may compensate for these limitations during development. Interaural time and level difference processing by neurons in the superior olivary complex depends on synaptic inhibition from the medial nucleus of the trapezoid body (MNTB), a group of inhibitory neurons that is activated by contralateral sound stimuli. In this study, we examined the maturation of coding properties of MNTB neurons and found that they receive an inhibitory influence from the ipsilateral ear that is modified during the course of postnatal development. Single neuron recordings were obtained from the MNTB in juvenile (postnatal day 15-19) and adult gerbils. Approximately 50% of all recorded MNTB neurons were inhibited by ipsilateral sound stimuli, but juvenile neurons displayed a much greater suppression of firing as compared with those in adults. A comparison of the prepotential and postsynaptic action potential indicated that inhibition occurred at the presynaptic level, likely within the cochlear nucleus. A simple linear model of level difference detection by lateral superior olivary neurons that receive input from MNTB suggested that inhibition of the MNTB may expand the response of LSO neurons to physiologically realistic level differences, particularly in juvenile animals, at a time when these cues are reduced.