Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA.
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
Curr Biol. 2024 Sep 9;34(17):4062-4070.e7. doi: 10.1016/j.cub.2024.07.053.
Some species have evolved the ability to use the sense of hearing to modify existing vocalizations, or even create new ones, which enlarges their repertoires and results in complex communication systems. This ability corresponds to various forms of vocal production learning that are all possessed by humans and independently displayed by distantly related vertebrates. Among mammals, a few species, including the Egyptian fruit bat, would possess such vocal production learning abilities. Yet the necessity of an intact auditory system for the development of the Egyptian fruit bat typical vocal repertoire has not been tested. Furthermore, a systematic causal examination of learned and innate aspects of the entire repertoire has never been performed in any vocal learner. Here we addressed these gaps by eliminating pups' sense of hearing at birth and assessing its effects on vocal production in adulthood. The deafening treatment enabled us to both causally test these bats' vocal learning ability and discern learned from innate aspects of their vocalizations. Leveraging wireless individual audio recordings from freely interacting adults, we show that a subset of the Egyptian fruit bat vocal repertoire necessitates auditory feedback. Intriguingly, these affected vocalizations belong to different acoustic groups in the vocal repertoire of males and females. These findings open the possibilities for targeted studies of the mammalian neural circuits that enable sexually dimorphic forms of vocal learning.
有些物种已经进化出利用听觉来修改现有的发声，甚至创造新的发声的能力，这扩大了它们的发声范围，形成了复杂的交流系统。这种能力对应着各种形式的发声学习，人类和远缘的脊椎动物都拥有这些能力，并独立表现出来。在哺乳动物中，包括埃及果蝠在内的少数物种就具有这种发声学习能力。然而，对于埃及果蝠典型的发声范围的发展来说，完整的听觉系统是否是必需的，这一点尚未得到检验。此外，在任何发声学习者中，对整个发声范围的习得和先天方面进行系统的因果检验也从未进行过。在这里，我们通过在出生时消除幼崽的听觉，并评估其对成年后发声的影响，来解决这些空白。失聪处理使我们能够对这些蝙蝠的发声学习能力进行因果检验，并辨别它们发声的习得和先天方面。利用来自自由互动的成年个体的无线个人音频记录，我们表明埃及果蝠发声范围的一部分需要听觉反馈。有趣的是，这些受影响的发声属于雄性和雌性发声范围中不同的声学群体。这些发现为研究哺乳动物神经回路提供了可能性，这些神经回路使性二态形式的发声学习成为可能。
