van Adel B A, Kidd S A, Kelly J B
Laboratory of Sensory Neuroscience, Institute of Neuroscience, Carleton University, Ottawa, Ont., Canada.
Hear Res. 1999 Apr;130(1-2):115-30. doi: 10.1016/s0378-5955(98)00226-3.
Binaural evoked responses were recorded with glass micropipettes from the central nucleus of the rat's inferior colliculus (ICC) before and after transection of the commissure of Probst (CP) with a microsurgical knife. The peak-to-peak amplitude of the averaged evoked response was measured for binaural clicks with interaural time differences (ITDs) between -1.0 and +30.0 ms (positive values reflecting ipsilateral-leading-contralateral click pairs). Before transection, the amplitude of the evoked response decreased as the ITD was shifted in favor of larger ipsilateral lead times. After transection of the CP, acoustic stimulation of the ipsilateral ear was much less effective in reducing evoked response amplitude. Responses to both short (+/-1.0 ms) and long (1.0-30.0 ms) ITD intervals were affected. After recordings were made, both anterograde and retrograde tract tracing methods were used to verify that the CP was completely transected and that all crossed projections from the dorsal nucleus of the lateral lemniscus (DNLL) to ICC were destroyed. The surgery completely eliminated the retrograde transport of fluorogold from the ICC to the opposite DNLL and blocked the anterograde transport of biotinylated dextran to contralateral DNLL and ICC. The physiological consequences of CP transection are attributed to the complete destruction of decussating, inhibitory (GABAergic) efferent projections from the DNLL.
用玻璃微电极在大鼠下丘中央核（ICC），于用显微手术刀切断普罗布斯特连合（CP）之前和之后记录双耳诱发反应。测量了双耳短声诱发反应的峰峰值幅度，双耳间时间差（ITD）范围为-1.0至+30.0毫秒（正值表示同侧领先对侧的短声对）。切断之前，随着ITD向更大的同侧领先时间偏移，诱发反应的幅度降低。切断CP后，同侧耳的声刺激在降低诱发反应幅度方面效果要小得多。对短（+/-1.0毫秒）和长（1.0 - 30.0毫秒）ITD间隔的反应均受到影响。记录完成后，采用顺行和逆行示踪方法来证实CP已被完全切断，并且外侧丘系背核（DNLL）到ICC的所有交叉投射均被破坏。手术完全消除了荧光金从ICC向对侧DNLL的逆行运输，并阻断了生物素化葡聚糖向对侧DNLL和ICC的顺行运输。CP切断的生理后果归因于DNLL交叉的抑制性（GABA能）传出投射被完全破坏。
