Acoustic Communication by Temporal Codes: Evolution and Neurobiology

Gerhardt博士的研究目标是获得有关脊椎动物声学通信机制和进化的知识。特别是，研究将侧重于时间编码，即在自然交流声音中重复元素的时间编码的信息。Gerhardt博士将对野生动物和杂交动物进行信号（声音）结构和识别这些声音的行为研究，他还将对听觉神经元对与生物相关的声音的时间模式的反应进行神经生理学研究。两种北美灰色树蛙（Hyla chrysoscelis和H. versicolor）将被研究。这些青蛙特别适合作为脊椎动物声音交流的模型系统，因为每个物种的雄性都会产生一组非常刻板的交流信号。雌性会对自然的和合成的（计算机生成的）信号做出可靠的反应，它们会接近扬声器，就像它们接近自然界中的雄性一样。雄蛙声音的计时特性不是后天习得的，而是在与声音隔绝的环境中正常发育的。这两个物种将通过人工杂交产生可行的杂交后代，从而为研究鸣叫和选择声音的遗传机制提供机会。在很多地区，只有一种鱼种，而在其他地区，两种鱼种同时在同一个池塘里繁殖，如果它们识别错误，就有可能产生不育的杂交鱼种。因此，来自重叠区域的雌性青蛙的选择性将与来自只有一个物种的区域的青蛙的选择性进行比较。树蛙的听觉系统已经得到了很好的研究，因此大量的基本信息已经可以作为时间编码的神经生理学研究的基础，这些研究将在这两个物种中进行。在本研究中，行为实验的结果将指导和补充神经生理学的工作。这项研究的结果将提供对脊椎动物所有声学通信系统的基本特性的见解。树蛙系统的强大之处在于，基因和神经生理学技术的结合可以用在高等动物身上不可能实现的方式。

The goal of Dr. Gerhardt's research is to gain knowledge about mechanisms and evolution of acoustic communication in vertebrate animals. In particular, the research will focus on temporal codes, that is, information encoded in the timing of repeated elements in natural communication sounds. Dr. Gerhardt will carry out behavioral studies of signal (sound) structure and the discrimination of these sounds, with both wild-type and hybrid animals, and he will also perform neurophysiological studies of the responses of auditory neurons to time patterns in sounds of biological relevance. Two species of North American gray treefrogs (Hyla chrysoscelis and H. versicolor) will be studied. These frogs are particularly suitable as a model system for vertebrate sound communication because males of each species produce a small set of very stereotyped communication signals. Females reliably respond to natural and synthetic (computer-generated) signals by approaching a loudspeaker, just as they approach a calling male in nature. The timing properties of the male's sounds are not learned, but develop normally when the frogs are raised in acoustic isolation. The two species will be cross-mated artificially to produce viable hybrids, thus affording the opportunity to study genetic mechanisms of both calling and selective approach to sounds. There are extensive areas where just one species occurs, and other areas where both species breed in the same ponds at the same time, at the risk of producing sterile hybrids if they make an error of identification. Thus, the selectivity of females from areas of overlap will be compared with that of frogs from areas where only one species occurs. The auditory system of treefrogs has been well studied, so that a great deal of basic information is already available as a foundation for the neurophysiological studies of time coding that will be done in these two species. In this research the results of the behavioral experiments will guide and complement the neurophysiological work. The results of this research should provide insights into fundamental properties of all acoustic communication systems in vertebrates. The treefrog system is especially powerful in that a combination of genetic and neurophysiological techniques can be used in ways that would be impossible in higher animals.