Department of Integrative Biology, The University of Texas at Austin, Austin, Texas, USA.
Department of Neurology, University of California Los Angeles, Los Angeles, California, USA.
J Comp Neurol. 2022 Aug;530(12):2075-2099. doi: 10.1002/cne.25321. Epub 2022 Apr 6.
Vocalizations are often elaborate, rhythmically structured behaviors. Vocal motor patterns require close coordination of neural circuits governing the muscles of the larynx, jaw, and respiratory system. In the elaborate vocalization of Alston's singing mouse (Scotinomys teguina) each note of its rapid, frequency-modulated trill is accompanied by equally rapid modulation of breath and gape. To elucidate the neural circuitry underlying this behavior, we introduced the polysynaptic retrograde neuronal tracer pseudorabies virus (PRV) into the cricothyroid and digastricus muscles, which control frequency modulation and jaw opening, respectively. Each virus singly labels ipsilateral motoneurons (nucleus ambiguus for cricothyroid, and motor trigeminal nucleus for digastricus). We find that the two isogenic viruses heavily and bilaterally colabel neurons in the gigantocellular reticular formation, a putative central pattern generator. The viruses also show strong colabeling in compartments of the midbrain including the ventrolateral periaqueductal gray and the parabrachial nucleus, two structures strongly implicated in vocalizations. In the forebrain, regions important to social cognition and energy balance both exhibit extensive colabeling. This includes the paraventricular and arcuate nuclei of the hypothalamus, the lateral hypothalamus, preoptic area, extended amygdala, central amygdala, and the bed nucleus of the stria terminalis. Finally, we find doubly labeled neurons in M1 motor cortex previously described as laryngeal, as well as in the prelimbic cortex, which indicate these cortical regions play a role in vocal production. The progress of both viruses is broadly consistent with vertebrate-general patterns of vocal circuitry, as well as with circuit models derived from primate literature.
发声通常是复杂的、有节奏结构的行为。发声的运动模式需要密切协调控制喉、颌和呼吸系统肌肉的神经回路。在 Alston 的鸣鼠（Scotinomys teguina）复杂的鸣叫声中，其快速、频率调制的颤音的每个音符都伴随着呼吸和张口的同样快速调制。为了阐明这种行为的神经回路，我们将多突触逆行神经元示踪剂伪狂犬病病毒（PRV）引入控制频率调制和颌开口的环甲肌和二腹肌。 每种病毒分别标记同侧运动神经元（疑核控制环甲肌，三叉运动核控制二腹肌）。我们发现，这两种同基因病毒强烈且双侧地标记巨细胞网状形成中的神经元，这是一种假定的中枢模式发生器。病毒还在包括腹外侧导水管周围灰质和臂旁核在内的中脑结构中显示出强烈的共标记，这两个结构强烈参与发声。在前脑，与社会认知和能量平衡都重要的区域都表现出广泛的共标记。这包括下丘脑的室旁核和弓状核、下丘脑外侧区、视前区、扩展杏仁核、中央杏仁核和终纹床核。最后，我们发现 M1 运动皮层中的双标记神经元以前被描述为喉，以及在前扣带皮层中，这表明这些皮层区域在发声产生中发挥作用。两种病毒的进展都与脊椎动物一般的发声回路模式以及从灵长类文献中得出的回路模型广泛一致。
