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Social Behavior
Social behavior is an essential component of daily life for many people all over the world. Studying social behavior in a similarly social species, such as rats, provides researchers a way to determine what it is about a social interaction that is particularly rewarding as well as the underlying mechanisms of disorders in which there is a severe lack of social behaviors, for example in autism spectrum disorder.
Playback of Ultrasonic Vocalizations
Seffer et al.(2014) The radial maze (A) with one active speaker (B) on one side. Experiments are conducted under red light (C), which rats cannot perceive, so the animals feel comfortable in “darkness”.Who is calling?
Rats emit ultrasonic vocalization in order to communicate and this calling behavior can be studied on an 8-arm radial maze. Two speakers are placed on opposite sides of the maze. With one of the speakers ultrasonic vocalizations are presented from one side. Depending on the calling type, rats will approach the active speaker, in case of appetitive 50-kHz calls, or in response to aversive 22-kHz calls will show a different behavior, like immobility or avoidance of the sound source.
This paradigm can be applied for example to study different neuropsychiatric disorders with impairments in communication, like autism spectrum disorder or schizophrenia. In addition, the approach behavior can be manipulated using substances that enhance the animal’s motivation to approach the call source.
Literature
Pro-social Choice Task
Shona Kayumova A friend in need: is there such a thing as a selfless act in the animal kingdom? The debate about it is still going on, but pro-sociality, for example helping, sharing, rescuing, is a well-documented behavior not just among humans.
In our lab we study pro-sociality of rats in terms of pro-social choice behaviour. During the pro-social choice task, a pair of rats (subject and partner rat) is trained in a maze, where a subject rat is facing two compartments, that differ only in the outcome of a partner rat. By choosing the “own reward” compartment the subject rat secures a food reward only for itself. On the other hand, a “both reward” compartment - a pro-social option - contains a food reward for both rats. It is known that rats choose more often a reward for both, themselves and for a partner, rather than just their own reward. Is that the case in different rat models though?
Recording Ultrasonic Vocalizations
We record rodent ultrasonic calls using specific ultrasound microphones which are sensitive to frequencies of up to 200 kHz (our hearing range ends at about 20 kHz). The signals are fed via an ultrasound interface (UltraSoundGate) into a PC, were the calls are displayed in real time by a specific software (Avisoft Recorder). Acoustical analysis of these recordings is provided by a specific software (SASLab Pro). Call detection itself is usually provided by an experienced user. From these calls, various parameters are then determined automatically, including call numbers and lengths, peak frequencies, frequency modulations, and amplitude. Also, the experimenter classifies the calls into different categories using these and other call criteria. In every experiment, calls are also down-sampled into signals audible to us humans to provide online experimental control, if required. Furthermore, visible behavior is usually recorded using cameras sensitive for low light conditions. These videos are used later on to relate call emission to other ongoing behaviors.
For further reading please see:
Wöhr, M., & Schwarting, R. K. (2013). Affective communication in rodents: ultrasonic vocalizations as a tool for research on emotion and motivation. Cell and tissue research, 354(1), 81-97.
Social Play - "Rough and Tumble Play"
Childhood is all about play! But did you know, for rats this is also true?
Typically, healthy young rats engage in fast past rough-and-tumble play with peers, often this involves components of wrestling, chasing and pinning. We know that this behavior is highly rewarding and leads to an increase in the emission of 50-kHz ultrasonic vocalizations. Similar to human children social play in young rats is not only fun but also essential to the development of the adult brain and social behavior repertoire. Abnormalities in, or prevention of, social play can lead to severe deficits in areas such as cognition, social interaction and communication as well as, emotional capabilities. Deficits in these areas can be reminiscent of several major disorders, for example Autism Spectrum Disorder or Schizophrenia. In our lab we measure social play and communication in young rats in an effort to establish a link between critical early development periods and genetic abnormalities contributing to the development of major affective and neurodevelopmental disorders (e.g. CACNA1C).
Find here: An interview with Markus Wöhr
Literature
Kisko, T. M., Braun, M. D., Michels, S., Witt, S. H., Rietschel, M., Culmsee, C., ... & Wöhr, M. (2018). Cacna1c haploinsufficiency leads to pro-social 50-kHz ultrasonic communication deficits in rats. Disease models & mechanisms, dmm-034116.
Seffer, D., Rippberger, H., Schwarting, R. K., & Wöhr, M. (2015). Pro-social 50-kHz ultrasonic communication in rats: post-weaning but not post-adolescent social isolation leads to social impairments—phenotypic rescue by re-socialization. Frontiers in behavioral neuroscience, 9, 102.
Three-Chambered Box
The three-chambered box is an apparatus originally developed to assess levels of sociability in mice. In the social approach task, a subject animal, while freely exploring the apparatus, has the choice between spending time with a social stimulus, i.e. a stranger animal that is placed in one chamber, or with a non-social stimulus i.e. an object located in the other chamber (Figure: upper panel – left). As mice and rats are social animals, they normally would show interest in a stranger and explore the chamber where it is located. Spending equal or more time with the object indicates reduced sociability. Decreases in sociability seen in animal models for neurodevelopmental disorders (e.g. SHANK1) may resemble the social deficits in individuals with Autism Spectrum Disorder – such as lacking interest in playing with other children, but engaging in non-social activities instead. The same apparatus can also be used for studying social recognition by presenting a familiar animal and a novel animal (Figure: upper panel – right). Typically, mice and rats prefer exploring the novel animal, and a lack in the novelty preference gives hints on social and memory deficits. During both tests ultrasonic vocalizations can be recorded, allowing us to assess subject’s communicative capability coupled to their social behavior.
Three-chambered box can also be used for testing cognitive abilities such as by means of novel object recognition. In this case, a subject animal is first allowed to freely explore the box containing two identical sample objects (Figure: lower panel – left). After a delay, one of the objects is replaced with a novel object of similar size but different in color, shape, and material to test novel object recognition memory (Figure: lower panel – right). Again, because of their naturally curious and exploratory nature, mice and rats would typically show interest in the novel object.
Literature