Neural cell-types and circuits linking thermoregulation and social behavior.

Understanding how social and affective behavioral states are controlled by neural circuits is a fundamental challenge in neurobiology. Despite increasing understanding of central circuits governing prosocial and agonistic interactions, how bodily autonomic processes regulate these behaviors is less resolved. Thermoregulation is vital for maintaining homeostasis, but also associated with cognitive, physical, affective, and behavioral states. Here, we posit that adjusting body temperature may be integral to the appropriate expression of social behavior and argue that understanding neural links between behavior and thermoregulation is timely. First, changes in behavioral states-including social interaction-often accompany changes in body temperature. Second, recent work has uncovered neural populations controlling both thermoregulatory and social behavioral pathways. We identify additional neural populations that, in separate studies, control social behavior and thermoregulation, and highlight their relevance to human and animal studies. Third, dysregulation of body temperature is linked to human neuropsychiatric disorders. Although body temperature is a "hidden state" in many neurobiological studies, it likely plays an underappreciated role in regulating social and affective states.

A circadian-dependent preference for light displayed by Xenopus tadpoles is modulated by serotonin.

Innate visually guided behaviors are thought to promote survival by guiding organisms to sources of food and safety and away from harm without requiring learning. Historically, innate behaviors have been considered hard-wired and invariable, but emerging evidence shows that many innate behaviors are flexible and complex due to modulation. Here, we investigate the modulation of the innate preference for light displayed by the Xenopus laevis tadpole, an exceptionally invasive and well-studied organism that is known to display several different innate visually guided behaviors. We found that tadpoles display a circadian-regulated oscillation in their preference for light over dark which can be altered by experimentally increasing or decreasing levels of serotonin transmission. We also found that endogenous levels of serotonin transmission during the day maintain a consistently moderate preference for light. Theoretically, a moderate preference for light, as opposed to a strong preference, optimizes survival by rendering tadpoles' behavior less predictable.