AUDIO-MOTOR INTERFACE IN ANURANS

Like males of many anuran species, fire-bellied toads (Bombina orienta lis) call antiphonally, which demonstrates an auditory input into the call-generating network. Males produce their calls by an inspiratory a irstream, which is generated exclusively by contraction of the muscles of the buccal cavity. The painted frog (Discoglossus pictus) possesse s a combined inspiratory and expiratory call mechanism, and also uses only buccal muscles. These muscles are controlled by branchial motoneu rons, which receive vocal premotor input mainly from the pretrigeminal nucleus. The interconnections between the auditory pathway and the vo cal pathway were examined by neuroanatomical tracing and intracellular recording. Mesencephalic auditory nuclei, laminar and magnocellular n ucleus of the torus semicircularis, and tegmental nuclei constitute st rong descending efferents, which, in turn, form collaterals that termi nate in vocal premotor nuclei. These findings imply fast audio-vocal i nterfacing, which is a prerequisite for the control of antiphonal call ing.