小鼠下丘听觉神经元的方位角灵敏度

AZIMUTH SENSITIVITY OF AUDITORY NEURONS IN INFERIOR COLLICULUS OF THE MOUSE

声源定位是听觉系统的主要功能之一。下丘作为听觉中脑的重要组成部分,在声源定位的过程中起到非常重要的作用。应用胞外记录方法研究小鼠下丘神经元对自由声场内不同方位声刺激的调谐特性。实验记录了100个下丘神经元,根据神经脉冲发放数与声源方位角关系曲线、最佳方位角(best azimuth, BA)位置和优势方位角范围(preferred azimuth range, PAR),可将其分为4类:对侧极大型神经元占79%,PAR为52.3°;双峰型神经元占14% ,PAR为68.0°;全向型神经元占5%,PAR为169.6°;同侧极大型神经元占2%,PAR为66.5°。实验结果说明,小鼠下丘神经元对方位角有很好的表达,对声源方位有选择性,并表明声音的方位信息在下丘进行了加工整合。本文还就下丘神经元方位编码的机制进行了探讨。

Sound source localization is one of main functions of auditory system. The inferior colliculus (IC), as an important nucleus of auditory midbrain, is crucial for sound localization. The neural responses of IC neurons to different sound azimuths were examined with extracellular recording tech-niques. The one hundred units recorded could be classified into four categories according to azimuth function curve, best azimuth and preferred azimuth range (PAR): contralateral-max neuron (79%), PAR (52.3 ± 25.0) ° ;two-peak neuron (14%), PAR (68.0 ± 26.6) ° ;omnidirectional neuron (5%), PAR (169.6 ± 9.1) ° ;ipsilateral-max neuron(2%),PAR (66.5 ± 28.5) ° . The results exhibit that IC neurons of the mouse can express and select sound-source azimuth. The results also show that sound-source informa-tion undergoes integrating processing in the inferior colliculus. The coding mechanisms of sound-source azimuth for IC neurons are discussed.