Acoustic communication in the fire-bellied toad: an integrative neurobiological approach

Fire-bellied toads of the genus Bombina belong to those anuran species which call consistently during the mating season. Unlike most other species they generate their calls via an inspiratory airstream. In response to conspecific calls males utter advertisement calls themselves. In order to avoid acoustic overlap, they try to place their calls into silent intervals between the calls of a conspecific male, which, in turn, leads to antiphonal calling. Vocal response and antiphonal calling are controlled by two different inputs from the auditory into the vocal pathway. The two inputs can be distinguished by their filter bandwidth, intensity characteristics, and the latencies between the onset of the response. Comparative behavioural and electromyographic studies reveal that the inhibition of call generation takes place with a delay of ca 60-80 msec after the onset of an auditory signal. Neuroanatomical investigations of the auditory and the vocal pathway by means of the HRP-technique reveal the anatomical basis for audio-vocal interactions at different levels of the toad's brain.