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.
Vocalizations, like many social displays, are often elaborate, rhythmically structured behaviors that are modulated by a complex combination of cues. Vocal motor patterns require close coordination of neural circuits governing the muscles of the larynx, jaw, and respiratory system. In the elaborate vocalization of Alstons singing mouse (Scotinomys teguina), for example, 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 ambiguous for cricothyroid, and motor trigeminal nucleus for digastricus). We find that the two isogenic viruses heavily and bilaterally co-label neurons in the gigantocellular reticular formation, a putative central pattern generator. The viruses also show strong co-labeling in compartments of the midbrain including the ventrolateral periaqueductal grey and the parabrachial nucleus, two structures strongly implicated in vocalizations. In the forebrain, regions important to social cognition and energy balance both exhibit extensive co-labeling. 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. Although we observe some novel patterns of double-labelling, 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.
on behalf of the Science of Variation Group Objectives: Two recent developments favor initial nonoperative treatment of proximal humerus fractures among the older, relatively infirm, less-active patients that represent most patients with such fractures: (1) evidence of minimal benefit of open reduction, internal fixation over nonoperative treatment, and (2) evidence of the effectiveness of the reverse total shoulder arthroplasty. As one step in determining the feasibility of a strategy of initial nonoperative treatment of proximal humerus fracture among older, relatively infirm, less-active people, we performed a survey-based experiment to measure factors associated with surgeon recommendation for initial nonoperative treatment.Methods: Members of the Science of Variation Group viewed 8 hypothetical patients with radiographs of complex proximal humeral fractures and 7 randomized patient variables. For each scenario, surgeons were asked whether they would recommend (1) initial nonoperative treatment with bailout reverse arthroplasty or (2) immediate reverse arthroplasty. Results:The mean percentage of recommendations for initial nonoperative treatment was 63%, with wide variation by surgeon (range 0%-100%). In multilevel mixed-effects logistic regression, recommendation for initial nonoperative treatment was associated with specific radiographs, older age, having a comorbidity, being homebound, surgical subspecialists, and more than 20 years in practice.Conclusions: These findings suggest that surgeons may consider initial nonoperative treatment with potential for future conversion to reverse arthroplasty an acceptable treatment option, particularly for older, less-active, more infirm individuals, and relatively less displaced fractures with little comminution.
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