Role of GABAergic inhibition in the coding of interaural time differences of low-frequency sounds in the inferior colliculus
Role of GABAergic inhibition in the coding of interaural time differences of low-frequency sounds in the inferior colliculus
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DOI：
10.1152/jn.00956.2004
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发表时间：
2005-06-01
影响因子：
2.5
通讯作者：
Kuwada, S
中科院分区：
文献类型：
--
作者：
D'Angelo, WR;Sterbing, SJ;Kuwada, S
声音在空间中定位的一个主要线索是耳间时差(ITD)。我们用多管移液管研究了抑制在下丘(IC)ITD反应形成中的作用，方法是通过离子电泳法喷射GABA拮抗剂和GABA本身。GABA拮抗剂阻断抑制，而应用的GABA提供恒定的抑制水平。在用药前、用药中和用药后评估对ITD反应的影响。如果GABA介导的抑制参与了IC神经元ITD调谐的形成，那么应用额外数量的这种抑制性递质应该会改变ITD调谐。事实上，对于几乎所有被测试的神经元，应用GABA降低了放电率，从而增强了ITD的调谐。相反，阻断GABA介导的抑制会增加IC神经元的活性，通常会降低信噪比，往往会扩大ITD的调谐范围。阻断GABA也可以改变ITD功能的形状并移动其峰值，这表明抑制的作用是多方面的。这些效应表明，在IC水平上的GABA能抑制对ITD编码是重要的。
A major cue for the localization of sound in space is the interaural time difference (ITD). We examined the role of inhibition in the shaping of ITD responses in the inferior colliculus (IC) by iontophoretically ejecting gamma-aminobutyric acid ( GABA) antagonists and GABA itself using a multibarrel pipette. The GABA antagonists block inhibition, whereas the applied GABA provides a constant level of inhibition. The effects on ITD responses were evaluated before, during and after the application of the drugs. If GABA-mediated inhibition is involved in shaping ITD tuning in IC neurons, then applying additional amounts of this inhibitory transmitter should alter ITD tuning. Indeed, for almost all neurons tested, applying GABA reduced the firing rate and consequently sharpened ITD tuning. Conversely, blocking GABA-mediated inhibition increased the activity of IC neurons, often reduced the signal-to-noise ratio and often broadened ITD tuning. Blocking GABA could also alter the shape of the ITD function and shift its peak suggesting that the role of inhibition is multifaceted. These effects indicate that GABAergic inhibition at the level of the IC is important for ITD coding.