Mapping the vocal circuitry of Alston's singing mouse with pseudorabies virus

• Published in: Journal of comparative neurology (1911) 2022-08, Vol.530 (12), p.2075-2099
• Main Authors: Zheng, Da‐Jiang, Okobi, Daniel E., Shu, Ryan, Agrawal, Rania, Smith, Samantha K., Long, Michael A., Phelps, Steven M.
• Format: Article
• Language: English
• Subjects: Amygdala; Animals; Central pattern generator; Cognition; Cortex (motor); Energy balance; Forebrain; Frequency dependence; Herpesvirus 1, Suid; Hypothalamus; Hypothalamus (lateral); Jaw; Larynx; Mesencephalon; Mice; Motor Cortex; Motor Neurons; Muscles; Neural networks; Nucleus ambiguus; Parabrachial nucleus; Periaqueductal gray area; Preoptic area; Prosencephalon - physiology; PRV; Pseudorabies; Respiratory system; Reticular formation; Scotinomys teguina; singing mice; Social interactions; Stria terminalis; Viruses; vocalization; Vocalization, Animal - physiology
• ISSN: 0021-9967; 1096-9861; 1096-9861
• DOI: 10.1002/cne.25321

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. In the vocalization of Alston's singing mouse (Scotinomys teguina), each note of its rapid frequency‐modulated trill is accompanied by modulation of larynx, breath, and gape. To elucidate the circuitry underlying song, we introduced the polysynaptic retrograde neuronal tracer pseudorabies virus (PRV) into two vocal muscles. We observed infection in separate motorneuron pools for each muscle, then coinfection in putative central pattern generators, followed by forebrain hypothalamic and limbic regions, and finally cortex. Our data suggest hierarchical song control resembles known circuits for both rodents and primates. Diagram depicts primate vocal circuitry; dark letters