Ultrasonic calling during fear conditioning in the rat: no evidence for an audience effect

doi:10.1016/j.anbehav.2008.04.017

Animal Behaviour

Volume 76, Issue 3, September 2008, Pages 749-760

https://doi.org/10.1016/j.anbehav.2008.04.017 Get rights and content

Rats, Rattus norvegicus, produce 22 kHz ultrasonic vocalizations in aversive situations such as during exposure to cats or fear conditioning. These calls are considered to be part of the animal's defensive repertoire and might serve as alarm signals for conspecifics. The aim of the present study was to test whether the production of 22 kHz calls is affected by the social context during fear conditioning. Animals were tested in one of three experimental conditions: either alone, with an anaesthetized conspecific, or with an active conspecific. In line with the hypothesized alarming function of 22 kHz calls, we expected the presence of a conspecific to potentiate the production of 22 kHz calls. The results, however, show that the production of 22 kHz calls during fear conditioning is clearly not potentiated by the presence of a conspecific; if at all, its presence had a mild attenuating effect on call rate. Also, call characteristics were similar in all three experimental conditions. Therefore, our findings do not support the hypothesis that the sender actively produces 22 kHz calls to warn conspecifics about danger.

Section snippets

Animals and Housing

We used 60 naïve male Wistar rats (HsdCpb:WU, Harlan-Winkelmann, Borchen, Germany), weighing 200–224 g on delivery. They were housed in groups of five in Macrolon type IV cages (380 × 200 mm and 590 mm high, plus high stainless steel covers) bedded with Tapvei peeled aspen bedding (indulab ag, Gams, Switzerland), and maintained in an animal room with a 12:12 h light:dark cycle (lights on 0700–1900 hours) at 21–25 °C (humidity: 45–70%). Lab chow (Altromin, Lage, Germany) and water (0.0004% HCl

Overt behaviour

Animals tested with an active cagemate tended to show more behavioural activity, but the statistical analysis did not yield evidence for a substantial difference, either during minutes 1–3 in the novel environment (immobility: χ₂² = 2.257, P = 0.324; rearing: χ₂² = 1.033, P = 0.596; grooming: χ₂² = 3.386, P = 0.184; Fig. 2), or during the following minutes 4–11 (immobility: χ₂² = 0.088, P = 0.957; rearing: χ₂² = 4.751, P = 0.093; grooming: χ₂² = 3.566, P = 0.168; Fig. 2).

Ultrasonic vocalization

Mere exposure to the novel environment did not

Discussion

The present fear-conditioning paradigm induced conditioned responses in overt behaviour and ultrasonic calling, which is in line with previous studies (Choi and Brown, 2003, Jelen et al., 2003, Wöhr et al., 2005, Borta et al., 2006, Wöhr and Schwarting, 2008). Also in accordance with previous studies, a positive correlation between immobility and 22 kHz calling was observed in experimental rats (Choi and Brown, 2003, Wöhr et al., 2005, Wöhr and Schwarting, 2008).

Acknowledgments

We thank Dorothée Domenger and Silke Eschert for their help on this project. This work was supported by a grant from the Deutsche Forschungsgemeinschaft (Schw 559/8-1).

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Ultrasonic calling during fear conditioning in the rat: no evidence for an audience effect

Section snippets

Animals and Housing

Overt behaviour

Ultrasonic vocalization

Discussion

Acknowledgments

Animal Behaviour

Brain Research Bulletin

Neuroscience and Biobehavioral Reviews

Physiology & Behavior

Animal Behaviour

Behavioural Brain Research

Neuroscience and Biobehavioral Reviews

Physiology & Behavior

Physiology & Behavior

Physiology & Behavior

Applied Animal Behaviour Science

Physiology & Behavior

Behavioural Brain Research

Animal Behaviour

Animal Behaviour

Animal Behaviour

Animal Behaviour

Animal Behaviour

Behavioural Brain Research

Physiology & Behavior

Physiology & Behavior

Behavioural Brain Research

Behavioural Brain Research

Brain Research

Behavioural Brain Research

Neuroscience Letters

Animal Behaviour

Behavioural Processes

European Journal of Pharmacology

Behavioural Brain Research

Pharmacology, Biochemistry and Behavior

Journal of Neuroscience Methods

Peptides

Neurobiology of Learning and Memory

The behavior of communicating: an analysis of the 22 kHz call of rats (Rattus norvegicus)

American Zoology

Sexual behavior: ultrasonic postejaculatory song of the male rat

Science