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Evaluating constant frequency 50 kHz ultrasonic vocalizations as an expression of anxiety in rats
Taylor, James Orion
Taylor, James Orion
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Date
2017
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Abstract
Adult rat ultrasonic vocalizations (USVs) are a valuable tool for noninvasively assessing an animals emotional state. The assessment of USVs can therefore enrich animal models of affective disorders. USVs are broadly classified into one of two frequency ranges: 22 kHz or 50 kHz. One subtype of 50 kHz USVs, constant frequency 50 kHz (CF 50 kHz) calls, is not viewed as signaling a particular emotional state. The data described in this dissertation provide support for the novel hypothesis that CF 50 kHz USVs are related to a low level of negative affective state, when threat is less certain or imminent (i.e., anxiety). The general procedure assessed vocalizations and other traditional behavioral indices of emotional state (i.e., rearing and freezing) in a paradigm of increasing certainty of threat through repeated mild footshocks to determine the vocal and overt behaviors associated with anxiety and fear.^^In a series of experiments, we assessed changes in these vocal and overt behaviors following modulations in emotional state through behavioral manipulations and peripherally- and centrally-administered pharmacological agents. Within the footshock paradigm, subjects transitioned from producing CF 50 to 22 kHz USVs as footshocks were repeated; a pattern paralleled by a shift from rearing behavior to increased time freezing. We additionally explored sex-related differences in behavior within this paradigm and determined that female rats provide a better model to explore this hypothesis because of the elevated rate of CF 50 kHz USVs compared to males. The results of these experiments were largely consistent with the hypothesis that CF 50 kHz USVs are related to anxiety. CF 50 kHz USVs are attenuated when the context is familiar and when subjects are pre-treated with the anxiolytics diazepam (1 mg/kg) and the corticotropin-releasing factor (CRF) antagonist α-helcial CRF.^^In contrast, CF 50 kHz USV production is increased when uncertain threat is first perceived, and when pre-treated with the anxiogenic CRF. The results of these experiments suggest that assessment of CF 50 kHz USVs may enrich existing animal models of anxiety and provide a tool for the development of new animal models and therapeutic interventions.
Contents
Subject
Subject(s)
Rats Vocalization.
Rats Behavior.
Anxiety.
Brain Psychophysiology.
Rats Behavior.
Anxiety.
Brain Psychophysiology.
Research Projects
Organizational Units
Journal Issue
Genre
Dissertation
Description
Format
1 online resource (vii, 149 pages) :
Department
Psychology