鸣禽的鸣唱行为是一种需要后天学习才能获得的复杂行为，依赖于幼年的听觉经历。然而对于临界型鸣禽成年后己结晶化的鸣唱的维持是否还需要听觉反馈，就目前的报道来看，不同种类存在较大差异。成年白腰文鸟被认为比其他临界型鸣禽，如斑雄草雀，白鹤雀和花鸡等，更强地依赖于听觉反馈。但这些研究并未注意到致聋年龄对鸣唱维持的影响。我们从音节序列的稳定性，音节结构，典型音节出现频率等三个方面比较年龄较大（18个月以上）和较年轻（5-6个月）成年白腰文鸟在丧失听力后鸣唱退化程度是否存在差异。结果显示，年轻组动物在致聋后，鸣唱的退化快而严重，与前人报道一致，但大年龄组动物鸣唱的退化显著减轻。提示年龄可能是影响成年后正常鸣唱维持对听觉反馈依赖性的重要因素。鸣声退化对听觉丧失的敏感性随年龄增大而降低。对于不同种类的临界型鸣禽，这种现象可能是普遍存在的。白腰文鸟成年鸣唱的维持对听觉反馈的强烈依赖，显示出其成熟脑内听觉通路与鸣唱通路之间持续进行着活跃的相互作用，并保持很强的可塑性。目前，对于成年鸣禽致聋后鸣唱退化的分子神经机制的研究还非常匮乏。我们选择了四种分子：与神经可塑性相关的突触素，与学习记忆相关的P物质以及对神经元胞质钙离子浓度调节至关重要的两种钙离子结合蛋白Calbindin和Calretinin，通过免疫组织化学技术，比较它们在年轻成年白腰文鸟致聋后脑内听觉发声系统中的表达变化。结果显示，动物致聋后，钙结合蛋白Calbindin在端脑听区复合体L3亚区的表达水平明显下降，阳性标记细胞显著减小；P物质在发声相关核团X区的表达水平显著下降；但突触素及钙结合蛋白Calretinin在主要听觉核团卵圆核（Ovoidalis, OV）、主要发声相关核团HVC、弓状皮层粗核（Robust nucleus of the arcopallium, RA）和前脑巢皮层外侧巨细胞核（Lateralmagnocellular nucleus of the anterior nidopallium, LMAN）中的表达均未出现显著性变化，提示，Calbindin与P物质可能参与了听觉依赖的神经活动，L3区可能在听觉信号向发声系统输入的过程中起关键作用，X区可能参与了成年后正常鸣唱的维持；致聋并不能引起听觉、发声核团内突触数目的变化，鸣唱行为的改变可能源于其他形式的突触可塑性。

Birdsong is a complex and learned behavior, relying on auditory experience in development. While the necessity of auditory feedback for stereotyped adult songs seems variably among different species in close-ended songbirds. Bengalese finches showed much heavier dependency on auditory feedback than others did. However, age effect of deafening on adult song in Bengalese finches hasn't been observed. In the present study, we compared the degree of songstructure degradation to hearing loss between old (over 18 months old) and young adult Bengalese finches (5-6 months old) from three aspects: song sequence stereotypy, syllable structure, typical syllable occurrence rate. We found that song deterioration in young adults was markedly severe and rapid as early reports, but in old adults, song degradation was significantly attenuated. Our results suggested that birds' age played an important role in affecting the dependency on auditory feedback for normal adult song maintenance. The declining susceptibility with age of adult song deterioration to hearing loss may be a common phenomenon for different species in close-ended songbirds. The heavy reliance on auditory feedback tomaintain adult song in Bengalese finches suggests that the mature auditory and vocal system remain active interaction and plasticity. We intend to know the neural mechanisms underlying this behavior changes. We chose four molecules: synaptophysin which regarded as a synapse marker, substance P which is related to memory and learning, calcium binding protein calbindin and calretinin to compare their expression level between normal and deaf young adult birds using immunohistochemistry method. We found that following hearing loss, expression ofcalbindin significantly decreased in subdivision L3 of primary auditory centre field L complex, and the calbindin positive neurons become smaller. Expression of substance P markedly decreased in area X of song system. Expression of synaptophysin and calretinin in Ovoidalis, the thalamus auditory nucleus, in HVC, Robust nucleus of the arcopallium (RA) and Lateral magnocellular nucleus of the anterior nidopallium (LMAN), the song system nuclei maintain normally. Our results indicated that calbindin and substance P could involve in the neural activity in auditory dependency, L3 might play a important role in the process of auditory information input to song system, are X might involve in adult song maintenance. And deafness couldn't change the number of synapses in auditory and song system, and the song changes might due toother ways of synapse plasticity.