Current research on gerbils

Project Details:
The monitoring and evaluation of emotions in animals is of increasing interest due to the public awareness on anima, welfare but also because laboratory animals serve as model species for the development of psychological drugs. The reliable evaluation of emotions is still a scientific challenge, as emotions are not only the result of automatic physiological reactions, but also underline cognitive evaluation processes (Kalat & Shiota, 2007). Thus, the emotional perception of a situation can depend on individual personality or experience. In order to be able to assess animal welfare, it is important to develop reliable methods for recording the emotional state of an animal. Although it is possible to determine an animal's condition using physiological measurements (e.g. blood sampling, implants to measure the heart rate), these measures are invasive and do not provide any information about the emotional valence of the condition (an increased heart rate occurs with both negative and positive emotions). An alternative is offered by behavioural tests that can be used to test the personality of animals as well as the emotional cognitive evaluation of a situation. One way of testing cognitive judgement is the ?Judgement Bias Task?. The animal learns to distinguish between a positive and a less positive stimulus and to react accordingly. They are then presented with an unknown ambivalent stimulus. Their reaction makes it possible to assess whether an animal is ?optimistic? (selects as with a positive stimulus) or ?pessimistic? (selects as with a positive stimulus). These findings will allow a better assessment of emotions in animals and can later be used to investigate the impact of different housing conditions, environmental enrichment or pharmacological effects on an animal's emotions.

Project Details:
A vocal repertoire contains a species-specific list of vocalizations, which are produced by the animals. These lists build the methodological and theoretical basis for a number of research questions of different disciplines. Nevertheless, there is no consensus how to establish a vocal repertoire or how to define call types. In the majority of studies, call types were established by visual classification, using spectrograms, which was supported by statistical analysis based on the measured acoustic features of a vocalization. In recent publications, more objective mathematically approaches such as supervised or unsupervised clustering algorithm were established. However, also these algorithm often require a pre-screening of the observer either because a number of expected clusters has to be determined or by the fact that the clustering result has to be proofed for their biological plausibility. Both methods can lead to an overestimation of call types especially in species with very variable vocalizations or graded call types. Thus, an acoustic variation alone is not sufficient to reflect a behavioural relevance. This also requires a context-specificity and the ability of the brain to perceive and process the acoustic variation. In this project, we aim to establish the vocal repertoires by combining the mathematical classification of the vocalizations with the behavioural contexts in which the calls were produced as well as the physical hearing abilities (e.g., hearing range, time- and frequency resolution) of the given species. We use this approach for two small-bodied mammalian species: the Mongolian gerbil, an important animal model for human hearing, and the Etruscan shrew, suggested to be a promising model for hearing in basal mammals due to its small eardrum, basal ossicles, and simple and thin cortex.

Results:

Langehennig-Peristenidou A, Felmy F, Scheumann M (2024). Graded calls of the smallest terrestrial mammal, the Etruscan shrew, living in a closed habitat. iScience, 27(12), 111297. DOI:10.1016/j.isci.2024.111297

 

Silberstein Y, Büntge J, Felmy F, Scheumann M (2024). Context or arousal? Function of drumming in Mongolian gerbils (Meriones unguiculatus). Frontiers in Zoology, 21(1), 22. DOI:10.1186/s12983-024-00542-2

 

Silberstein Y, Felmy F, Scheumann M (2023). Encoding of arousal and physical characteristics in audible and ultrasonic vocalizations of Mongolian gerbil pups testing common rules for mammals. Animals (Basel), 13(16), 2553. DOI:10.3390/ani13162553

Cooperation Partners:

Prof. Dr. A. Kral, VIANNA, Klinik und Poliklinik für Hals-, Nasen- und Ohrenheilkunde

Dr. Wiebke Konerding, VIANNA, Klinik und Poliklinik für Hals-, Nasen- und Ohrenheilkunde