Nevue Alexander A, Mello Claudio V, Portfors Christine V
College of Arts and Sciences, Washington State University, Vancouver, WA, 98686.
Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, 97239.
bioRxiv. 2023 Jun 26:2023.06.26.546619. doi: 10.1101/2023.06.26.546619.
Cortical neurons that make direct connections to motor neurons in the brainstem and spinal cord are specialized for fine motor control and learning [1, 2]. Imitative vocal learning, the basis for human speech, requires the precise control of the larynx muscles [3]. While much knowledge on vocal learning systems has been gained from studying songbirds [4], an accessible laboratory model for mammalian vocal learning is highly desirable. Evidence indicative of complex vocal repertoires and dialects suggests that bats are vocal learners [5, 6], however the circuitry that underlies vocal control and learning in bats is largely unknown. A key feature of vocal learning animals is a direct cortical projection to the brainstem motor neurons that innervate the vocal organ [7]. A recent study [8] described a direct connection from the primary motor cortex to medullary nucleus ambiguus in the Egyptian fruit bat (. Here we show that a distantly related bat, Seba's short-tailed bat () also possesses a direct projection from the primary motor cortex to nucleus ambiguus. Our results, in combination with Wirthlin et al. [8], suggest that multiple bat lineages possess the anatomical substrate for cortical control of vocal output. We propose that bats would be an informative mammalian model for vocal learning studies to better understand the genetics and circuitry involved in human vocal communication.
与脑干和脊髓中的运动神经元直接相连的皮层神经元专门负责精细运动控制和学习[1,2]。模仿性发声学习是人类语言的基础,需要精确控制喉部肌肉[3]。虽然通过研究鸣禽已经获得了很多关于发声学习系统的知识[4],但非常需要一个便于研究的哺乳动物发声学习实验室模型。表明存在复杂发声 repertoire 和方言的证据表明蝙蝠是发声学习者[5,6],然而蝙蝠中发声控制和学习的神经回路在很大程度上尚不清楚。发声学习动物的一个关键特征是皮层直接投射到支配发声器官的脑干运动神经元[7]。最近一项研究[8]描述了埃及果蝠( )的初级运动皮层与延髓疑核之间的直接连接。在这里我们表明,一种亲缘关系较远的蝙蝠,塞氏短尾蝠( )也具有从初级运动皮层到疑核的直接投射。我们的结果与维特林等人[8]的结果相结合,表明多个蝙蝠谱系拥有皮层控制发声输出的解剖学基础。我们提出,蝙蝠将是用于发声学习研究的一个有价值的哺乳动物模型,以便更好地理解人类语音交流中涉及的遗传学和神经回路。