Midbrain and brainstem of control of vocalizations in neutral and playful contexts

Vocalizations in mammals require precise timing and control over a multitude of muscles. Our project will address four aspects of mammalian vocalization control: (i) We try to delineate more precisely the circuitry forming the mammalian brain stem vocal pattern generator. This work is a continuation of our earlier VPG mapping work with cooling and large-scale recordings. This work will proceed in anesthetized animals, in which calls are
evoked by midbrain stimulation. If possible, we will compare the circuits delineated in rats with humans and perhaps also nonhuman primates. (ii) We will investigate how these brainstem circuits are controlled by the periaqueductal grey. In this project part we will combine viral tracing with large scale recordings of periaqueductal gray and brainstem in awake animals. This project part focuses on the anatomical and activity-based interactions of periaqueductal gray and brainstem (iii) In the third part of the project, we will try to understand how periaqueductal grey population activity predicts vocalizations. Here, we will address a riddle in the field of mammalian vocalization control, i.e., it is clear that the periaqueductal gray is absolutely essential for vocalizations, yet in single-cell analysis only a small fraction of periaqueductal gray cells discharges in relation to vocalizations. We will use large-scale multi-shank Neuropixel recordings to assess what population activity can tell us about the relationship of periaqueductal gray and vocalizations. (iv) In the final part of our project, we will investigate how vocalizations and periaqueductal gray coordinate playfulness across rats. Play-fighting is a non-violent form of interactions between playful individuals. In both humans and rats, play-fighting and tickling are less often initiated and are less fun in the absence of vocalizations. We will determine how vocalization-mediated playfulness is mediated by periaqueductal gray activity.