Auditory and vocal nuclei in the frog brain concentrate sex hormones

Mate calling by South African clawed frogs, Xenopus laevis, is under the control of androgens. Autoradiographic studies demonstrate androgen-concentrating neurons in a motor nucleus that controls mate calling and a midbrain nucleus that is stimulated by sound. Hormone concentration by laryngeal motor neurons suggests that steroids regulate the final common path for vocal behavior. Modulation of auditory sensitivity by hormones could explain seasonal variations in behavioral responsiveness to conspecific vocalizations.