Department of Anatomy and Neurobiology, Northeastern Ohio Universities Colleges of Medicine and Pharmacy, Rootstown, Ohio 44272, USA.
J Neurosci. 2011 Apr 20;31(16):6121-31. doi: 10.1523/JNEUROSCI.4733-10.2011.
Tonic inhibition mediated by extrasynaptic GABA(A) receptors (GABA(A)Rs) has emerged as a novel form of neural inhibition in the CNS. However, little is known about its presence and function in the auditory system. Using whole-cell recordings in brain slices, we identified a tonic current mediated by GABA(A)Rs containing the δ subunit in middle/high-characteristic-frequency neurons of the chicken nucleus laminaris, the first interaural time difference encoder that computes information for sound localization. This tonic conductance was activated by ambient concentrations of GABA released from synaptic vesicles. Furthermore, pharmacological manipulations of the conductance demonstrated its essential role in coincidence detection. Remarkably, this depolarizing tonic conductance was strongly inhibitory primarily because of its shunting effect. These results demonstrate a novel role for tonic inhibition in central auditory information processing.
突触外 GABA(A) 受体（GABA(A)Rs）介导的紧张性抑制作用已成为中枢神经系统中一种新的神经抑制形式。然而，其在听觉系统中的存在和功能知之甚少。通过在脑切片上进行全细胞膜片钳记录，我们在鸡核层状体的中/高频特征频率神经元中鉴定出一种由δ亚基组成的 GABA(A)R 介导的紧张性电流，该神经元是第一个用于声音定位的计算双耳时差信息的听觉中间神经元。这种紧张性电导被来自突触小泡的 GABA 的环境浓度激活。此外，对电导的药理学操作表明其在检测偶合方面的重要作用。值得注意的是，这种去极化紧张性电导具有很强的抑制作用，主要是由于其分流效应。这些结果表明紧张性抑制在中枢听觉信息处理中具有新的作用。
