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Published on: September 3, 2015
Using bedding in a test environment critically affects 50-kHz ultrasonic vocalizations in laboratory rats
1Experimental and Physiological Psychology, Philipps-University of Marburg, Gutenbergstr. 18, 35032 Marburg, Germany. natusch@staff.uni-marburg.de
Pharmacology, Biochemistry, and Behavior
|May 25, 2010
Summary
Rats emit 50-kHz ultrasonic vocalizations more often in the presence of fresh bedding, suggesting bedding induces a positive affective state. This indicates context significantly influences rat vocalizations and emotional states.
Area of Science:
- Animal Behavior
- Neuroscience
- Animal Welfare
Background:
- Rats produce distinct ultrasonic vocalizations (USVs), including 50-kHz calls, linked to rewarding stimuli, drug use, and environmental factors.
- Previous research suggests 50-kHz calls correlate with positive affective states, but the influence of subtle environmental cues is underexplored.
Purpose of the Study:
- To investigate the impact of fresh rodent bedding on 50-kHz ultrasonic vocalizations in rats.
- To determine if bedding influences vocalization responses to rewarding stimuli (tickling) and psychostimulant administration (amphetamine).
- To assess the relationship between bedding, affective state, and behavioral activation.
Main Methods:
- Adult male rats were tested in both bedded and bare cages under various conditions: baseline, during tickling, and after amphetamine administration.
- Ultrasonic vocalizations (USVs) were recorded and analyzed, alongside measures of psychomotor activity (locomotion, rearing).
- A choice procedure was used to assess rat preference for bedded versus bare conditions.
Main Results:
- Rats emitted significantly more 50-kHz calls in bedded cages compared to bare cages.
- Tickling and amphetamine administration led to increased 50-kHz vocalizations in the presence of bedding.
- While bedding affected vocalizations, it did not consistently alter general psychomotor activity, and vocalization patterns differed from behavioral activation profiles.
- Rats showed a clear preference for bedded environments.
Conclusions:
- Fresh rodent bedding can induce a positive affective state in rats, increasing the frequency of 50-kHz ultrasonic vocalizations.
- Contextual factors like bedding play a crucial role in modulating rat emotional states and vocal behavior, potentially reducing testing aversiveness.
- Measuring rat USVs is valuable for assessing emotional and motivational states, providing insights not always apparent from overt behavior, especially in research on emotion and motivation.
