Date of Award

2019

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Leininger, Elizabeth

Area of Concentration

Neurobiology

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, I examined X. muelleri, a close relative of X. borealis, which produces advertisement calls of intermediate complexity. After recording vocalizations from live frogs, I stimulated laryngeal nerve rootlets of the isolated larynx with stimulus bursts over a range of inter-stimulus intervals approximating their burst advertisement call while recording electromyograms and tension from the laryngeal muscle. Stimulus bursts with intervals (45 - 60 ms) greater than or equal to the average inter-pulse interval recorded from intact frogs produced the two discrete EMG and tension transients necessary for a burst call while stimulus bursts with shorter inter-pulse intervals (20 - 35 ms) resulted in maintained tension, correlating to the production of 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 like their in vivo calls.

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