Jen Philip H S, Feng Ruiben, Chen Brian
Division of Biological Sciences University of Missouri Columbia, Columbia, MO 65211, USA.
Chin J Physiol. 2003 Jun 30;46(2):83-90.
GABAergic inhibition shapes many auditory response properties of neurons in the inferior colliculus of the big brown bat, Eptesicus fuscus. This study examined the role of GABAergic inhibition on direction-dependent rate-intensity functions of bat inferior collicular neurons. When plotted at three sound directions (60 degrees contralateral, 0 degrees and 60 degrees ipsilateral relative to recording site), most collicular neurons had nonmonotonic and saturated rate-intensity functions at 60 degrees contralateral and 0 degrees but had monotonic rate-intensity functions at 60 degrees ipsilateral. The dynamic range of rate-intensity functions of majority (>90%) of collicular neurons significantly decreased as the sound direction changed from 60 degrees contralateral to 60 degrees ipsilateral. Bicuculline application increased or decreased the dynamic range of IC neurons in different degrees with sound direction and abolished direction-dependent intensity sensitivity of these IC neurons. Possible mechanisms for these observations are discussed.
γ-氨基丁酸（GABA）能抑制作用塑造了大棕蝠（棕蝠）下丘神经元的许多听觉反应特性。本研究探讨了GABA能抑制作用对蝙蝠下丘神经元方向依赖性速率-强度函数的作用。当在三个声音方向（相对于记录部位，对侧60度、0度和同侧60度）绘制时，大多数下丘神经元在对侧60度和0度处具有非单调和饱和的速率-强度函数，但在同侧60度处具有单调的速率-强度函数。随着声音方向从对侧60度变为同侧60度，大多数（>90%）下丘神经元的速率-强度函数动态范围显著减小。应用荷包牡丹碱会随着声音方向不同程度地增加或减小下丘神经元的动态范围，并消除这些下丘神经元的方向依赖性强度敏感性。文中讨论了这些观察结果的可能机制。
