Postnatal development and plasticity of sound localization centers

<Neurogenetical study>结合荧光逆行轴突示踪和溴脱氧尿苷（BrdU）免疫组织化学技术，研究了上级橄榄核投射神经元的时间起源。在外侧上级橄榄核中，投射到对侧下丘（IC）的神经元在E12和E13天产生，而投射到同侧IC的神经元在E14和E16天之间增殖。在内侧上级橄榄（MSO），IC投射神经元出现在E12，而在上级橄榄旁核，其高峰生产发生在E13天。还参考一些出版物（Kitao等人，brain Research，1993）和口头报告（International Workshopon Binaural Processing in the Auditory Brainstem.渥太华，加拿大，1993年;神经科学学会，阿纳海姆，加州，1992年）。<Normal development of auditory brainstem pathways and plasticity after unilateral ablation of the IC>结果表明：（1）生后MSO向IC的投射逐渐发展，形成一条完全不交叉的投射，不与对侧IC形成轴突侧支。（2）生后一定时期单侧切断IC，同侧MSO内有大量神经元因切断轴突而死亡。3)在MSO中，一些存活的神经元发生向对侧IC的异常交叉投射，尽管这种异常纤维在成人中仍然保留的数量很少。4)后期发展的轴突的增长是一个主要因素，在可塑性这一系统的投影。

<Neurogenetical study>By a combination of fluorescent retrograde axonal tracings and bromodeoxyuridine (BrdU) immunohistochemical techniques, time origins of projection neurons in the superior olive have been examined. In the lateral superior olive, neurons projecting to the contralateral inferior colliculus (IC) were generated on days E12 and E13, whereas neurons projcting to the ipsilateral IC were proliferated between days E14 and E16. In the medial superior olive (MSO), the IC projection neurons arose on E12, while, in the superior paraolivary nucleus, their peak production occurred on day E13. Also refer some publication (Kitao et al., brain Research, 1993) and oral presentations (International Workshopon Binaural Procssing in the Auditory Brainstem. Ottawa, Canada, 1993 ; Society for Neuroscience.Anaheim, California U.S.A., 1992).<Normal development of auditory brainstem pathways and plasticity after unilateral ablation of the IC>The results indicated that : 1) The projection froj the MSO to the IC was developed gradually in postnatal periodsas an exclusively uncrossed one without making axon-collaterals to the contralateral IC.2) When the IC was ablated unilaterally in certain postnatal period, many neurons died in the ipsilateral MSO as a result of axotomy. 3) An aberrant crossed projection to the contralateral IC occurs in some of the survived neurons in the MSO, although such aberrant fibers still maintained in adult were very few in number. 4) Growth of late-developing axons was a major factor in the plasticity of this system of projection.