Corticofugal modulation of the paradoxical latency shifts of inferior collicular neurons
Corticofugal modulation of the paradoxical latency shifts of inferior collicular neurons
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DOI：
10.1152/jn.90508.2008
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发表时间：
2008-08-01
影响因子：
2.5
通讯作者：
Suga, Nobuo
中科院分区：
文献类型：
--
作者：
Ma, Xiaofeng;Suga, Nobuo
中枢听觉系统产生各种类型的神经元，这些神经元被调谐到不同的声学参数，而不是特定的频率。听觉神经元的反应潜伏期通常会随着刺激强度的增加而缩短。然而，与10%的小棕色蝙蝠的丘神经元相似，它们表现出一种“矛盾的潜伏期移动”：强烈声音的潜伏期较长，而微弱声音的潜伏期较短。据推测，这些神经元参与了一对强烈的生物声纳脉冲及其微弱回声携带的目标距离信息的处理。我们目前的研究表明，大棕色蝙蝠的丘脑室旁核神经元受到皮质分离(下行)系统的调制。电刺激皮层听神经元可引起两种类型的改变，这取决于刺激的皮质神经元和记录到的丘神经元之间的最佳频率(BF)的关系。当BF匹配时，皮质刺激不会使丘神经元的BF发生改变，并使其对强音的反应潜伏期缩短，从而使偏最小二乘反应变小。然而，当BF不匹配时，皮质刺激使丘神经元的BF移位，并延长其对强烈声音的反应潜伏期，从而使偏最小二乘法变大。皮质电刺激也调制了非偏最小二乘神经元的反应潜伏期。它产生了一条或多条抑制频率调谐曲线。我们的发现表明，皮质分离反馈可能通过抑制参与了皮质下听神经元反应的光谱时间模式的形成。
The central auditory system creates various types of neurons tuned to different acoustic parameters other than a specific frequency. The response latency of auditory neurons typically shortens with an increase in stimulus intensity. However, similar to 10% of collicular neurons of the little brown bat show a "paradoxical latency-shift (PLS)": long latencies to intense sounds but short latencies to weak sounds. These neurons presumably are involved in the processing of target distance information carried by a pair of an intense biosonar pulse and its weak echo. Our current studies show that collicular PLS neurons of the big brown bat are modulated by the corticofugal (descending) system. Electric stimulation of cortical auditory neurons evoked two types of changes in the PLS neurons, depending on the relationship in the best frequency (BF) between the stimulated cortical and recorded collicular neurons. When the BF was matched between them, the cortical stimulation did not shift the BFs of the collicular neurons and shortened their response latencies at intense sounds so that the PLS became smaller. When the BF was unmatched, however, the cortical stimulation shifted the BFs of the collicular neurons and lengthened their response latencies at intense sounds, so that the PLS became larger. Cortical electric stimulation also modulated the response latencies of non-PLS neurons. It produced an inhibitory frequency tuning curve or curves. Our findings indicate that corticofugal feedback is involved in shaping the spectrotemporal patterns of responses of subcortical auditory neurons presumably through inhibition.