Department of Anatomy and Neurobiology, Northeastern Ohio Universities Colleges of Medicine and Pharmacy, Rootstown, Ohio, United States of America.
PLoS One. 2011 Mar 9;6(3):e17460. doi: 10.1371/journal.pone.0017460.
Adult mice are highly vocal animals, with both males and females vocalizing in same sex and cross sex social encounters. Mouse pups are also highly vocal, producing isolation vocalizations when they are cold or removed from the nest. This study examined patterns in the development of pup isolation vocalizations, and compared these to adult vocalizations. In three litters of CBA/CaJ mice, we recorded isolation vocalizations at ages postnatal day 5 (p5), p7, p9, p11, and p13. Adult vocalizations were obtained in a variety of social situations. Altogether, 28,384 discrete vocal signals were recorded using high-frequency-sensitive equipment and analyzed for syllable type, spectral and temporal features, and the temporal sequencing within bouts. We found that pups produced all but one of the 11 syllable types recorded from adults. The proportions of syllable types changed developmentally, but even the youngest pups produced complex syllables with frequency-time variations. When all syllable types were pooled together for analysis, changes in the peak frequency or the duration of syllables were small, although significant, from p5 through p13. However, individual syllable types showed different, large patterns of change over development, requiring analysis of each syllable type separately. Most adult syllables were substantially lower in frequency and shorter in duration. As pups aged, the complexity of vocal bouts increased, with a greater tendency to switch between syllable types. Vocal bouts from older animals, p13 and adult, had significantly more sequential structure than those from younger mice. Overall, these results demonstrate substantial changes in social vocalizations with age. Future studies are required to identify whether these changes result from developmental processes affecting the vocal tract or control of vocalization, or from vocal learning. To provide a tool for further research, we developed a MATLAB program that generates bouts of vocalizations that correspond to mice of different ages.
成年老鼠是高度发声的动物，雄性和雌性在同性和异性社交接触中都会发声。幼鼠也非常爱发声，当它们感到寒冷或离开巢穴时，会发出隔离叫声。本研究检查了幼鼠隔离叫声发育的模式，并将其与成年老鼠的叫声进行了比较。在三个 CBA/CaJ 幼鼠窝中，我们在出生后第 5 天（p5）、p7、p9、p11 和 p13 时记录了隔离叫声。成年老鼠的叫声是在各种社交情况下获得的。总共使用高频敏感设备记录了 28384 个离散的声音信号，并对音节类型、频谱和时间特征以及音节组合内的时间顺序进行了分析。我们发现，幼鼠产生了成年老鼠记录的 11 种音节类型中的 10 种。音节类型的比例随发育而变化，但即使是最小的幼鼠也会产生具有频率-时间变化的复杂音节。当所有音节类型一起进行分析时，从 p5 到 p13，音节的峰值频率或持续时间的变化虽然很小，但却具有统计学意义。然而，单个音节类型在发育过程中表现出不同的、大的变化模式，需要分别分析每个音节类型。大多数成年音节的频率明显较低，持续时间较短。随着幼鼠年龄的增长，发声行为的复杂性增加，音节类型之间的转换趋势增强。来自年龄较大的动物（p13 和成年）的发声行为比来自年幼老鼠的发声行为具有更多的序列结构。总的来说，这些结果表明，随着年龄的增长，社会发声行为发生了实质性的变化。未来的研究需要确定这些变化是由于影响发声器官或发声控制的发育过程，还是由于发声学习所致。为了提供进一步研究的工具，我们开发了一个 MATLAB 程序，可以生成与不同年龄的老鼠相对应的发声行为。
