George Isabelle, Cousillas Hugo, Richard Jean-Pierre, Hausberger Martine
Université de Rennes 1, Unité Mixte de Recherche Centre National de la Recherche Scientifique 6552, Ethologie-Evolution-Ecologie, Campus de Beaulieu, France.
J Comp Neurol. 2005 Jul 18;488(1):48-60. doi: 10.1002/cne.20584.
Lateralization of brain functions is a widespread phenomenon in vertebrates. With the well-known lateralization in the processing of human speech and the parallels that exist between birdsong and language, songbirds are interesting for addressing such questions. In the present study, we investigated the central processing of communicative and artificial sounds in starlings, in an integrative part of the song system: the HVC. Neuronal responses to acoustic stimuli were systematically recorded in both hemispheres while the birds were awake, and then anesthetized, allowing quantitative comparisons of the responses obtained in each situation. The total proportion of responsive sites in the HVC of the left and right hemispheres of all birds revealed a significant predominance of the HVC of the right hemisphere when the birds were awake, whereas a high interindividual variability appeared when the birds were anesthetized. When neuronal responses as a whole were further examined, the responses to each type of stimulus appeared to be nonrandomly distributed over the different situations, and some specialization may appear. The results suggest a complex and state-dependent hemispheric specialization toward behaviorally relevant classes of stimuli. In awake birds, the HVC of the left hemisphere may be more involved in the processing of songs that are used in individual recognition at distance, whereas the HVC of the right hemisphere may deal with long and complex sequences of a song that is involved in short-distance communication, especially between males and females. With birds under anesthesia, this pattern is strongly modified.
脑功能的偏侧化是脊椎动物中普遍存在的现象。鉴于人类语言处理中众所周知的偏侧化以及鸟鸣与语言之间存在的相似之处，鸣禽对于解决此类问题很有研究价值。在本研究中，我们在鸣禽歌声系统的一个整合部分——HVC中，研究了椋鸟对交流声音和人工声音的中枢处理。在鸟类清醒和麻醉状态下，系统地记录了两侧半球对声学刺激的神经元反应，从而能够对每种情况下获得的反应进行定量比较。所有鸟类左右半球HVC中反应位点的总比例显示，鸟类清醒时右半球的HVC明显占主导，而鸟类麻醉时个体间差异很大。当进一步检查整体神经元反应时，对每种刺激类型的反应似乎在不同情况下呈非随机分布，可能存在一些特化现象。结果表明，针对行为相关刺激类别存在复杂且依赖状态的半球特化。在清醒的鸟类中，左半球的HVC可能更多地参与远距离个体识别中使用的歌声处理，而右半球的HVC可能处理参与近距离交流（尤其是雌雄之间）的长而复杂的歌声序列。在麻醉的鸟类中，这种模式会发生强烈改变。
