Meeting Abstract
Understanding the mechanisms underlying the evolution of behaviors relies on identifying modifications to neural and muscular circuit physiology. Male African clawed frogs (Xenopus) produce species specific advertisement calls that vary in temporal complexity. Species that produce temporally simplified advertisement calls (X. borealis and X. boumbaensis) utilize different laryngeal mechanisms for generating these calls. Unlike X. boumbaensis, X. borealis faithfully converts neural stimulation into muscle contractions that mirror call temporal patterns. To understand whether this mechanism is conserved, we examined X. muelleri, a species closely related to X. borealis, that produces advertisement calls of intermediate complexity. We identified stimulation parameters required to produce muscle contractions approximating the burst advertisement call of X. muelleri. After recording vocalizations from live frogs, we stimulated laryngeal nerve rootlets of the isolated larynx with stimulus bursts over a range of inter-stimulus intervals while recording electromyograms and tension from the laryngeal muscle. Stimulus bursts delivered to the larynx with inter-stimulus intervals (50 – 60 ms) longer than the average inter-pulse interval recorded from intact frogs (45 ms) produced the two discrete EMG and tension transients necessary for a burst call. However, stimulus bursts delivered to the isolated larynx with shorter inter-pulse intervals (20 – 40 ms) resulted in maintained tension, which would correlate to producing a single sound pulse rather than a burst. These results confirm that X. muelleri displays faithful conversion of neural stimulation to muscle contractions, but can only do so at intervals at or longer than those of in vivo calls.
