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Learning and Memory
A brain's capacity to learn and form memories has long fascinated researchers. Using animal models in paradigms that explore a variety of cognitive functions allows researchers to explore things such as the neurocircuitry underlying fear conditioning as well as determine what cognitive impairments may result from psychiatric or neurodevelopmental disorders.
Fear Conditioning
We survive by remembering. But sometimes we survive by forgetting.
Like in humans, rodents can easily learn to associate a certain cue (e.g. a tone) with a negative outcome (e.g. mild electric shock). The possibility to adapt this classical conditioned response when the surrounding conditions change is even more important. When a tone no longer signals a possible threat, the anticipated reaction should decrease. The learnt behavior should no longer be displayed.
To assess whether different manipulations can influence this (re)learning behavior, we use an auditory cued fear conditioning paradigm. Here, anxiety-related behaviors, like freezing and negatively connoted 22-kHz ultrasonic vocalizations are measured.
Literature
Yee, N., Schwarting, R. K., Fuchs, E., & Wöhr, M. (2012). Juvenile stress potentiates aversive 22-kHz ultrasonic vocalizations and freezing during auditory fear conditioning in adult male rats. Stress, 15(5), 533-544.
Borta, A., Wöhr, M., & Schwarting, R. K. W. (2006). Rat ultrasonic vocalization in aversively motivated situations and the role of individual differences in anxiety-related behavior. Behavioural brain research, 166(2), 271-280.
Object Recognition
Hello again!
The recognition of already known objects is a core feature in memory function. This ability to remember objects can be influenced by pharmacological manipulations, genetic factors or environmental changes. To assess the episodic memory, we use the novel object recognition test.
First, animals are familiarized with two identical objects (e.g. cylinders, cuboids etc.). After a delay, the familiar object and a new one are presented. If remembered correctly, rats or mice typically spend more time investigating the new object via sniffing and moving towards it. Various treatments or genetic background influence this behavior, indicating changes in memory function.
Literature
Ludwig, V., Mihov, Y., & Schwarting, R. K. W. (2008). Behavioral and neurochemical consequences of multiple MDMA administrations in the rat: role of individual differences in anxiety-related behavior. Behavioural brain research, 189(1), 52-64.
Reversal Learning
Forget everything you just learned!
Behavioral and cognitive flexibility are a form of cognition enabling not only humans but also animals to adapt their behavior to changing environmental conditions. In experimental conditions this can be measured through the reversal learning task. In rats and mice, for example, this may involve the animal learning to associate a reward with a specific stimulus. Once established the stimulus-reward contingency is reversed and the animal must now override the original learned response and change to learn the new stimulus-reward response. In our lab this is done through the animal learning the location of hidden treats within a maze by navigating with spatial cues placed around the room. Once the animal has successfully learned the location of the treats the experimenter changes the locations and then the goal is to measure how long it takes the animal to (re)learn the new treat location. Animal models for neuropsychiatric disorders in which cognitive impairments are often associated (e.g. Cacna1c) can be used in this paradigm to help uncover possible mechanisms contributing to impairments in cognitive abilities.
Literature
Braun, M. D., Kisko, T. M., Dalla Vecchia, D., Andreatini, R., Schwarting, R. K., & Wöhr, M. (2018). Sex-specific effects of Cacna1c haploinsufficiency on object recognition, spatial memory, and reversal learning capabilities in rats. Neurobiology of learning and memory.
Sign-and-Goal Tracking
Why do some people become addicts?
Sometimes a neutral stimulus (a sign) becomes desirable on its own and the presentation of it, even in the absence of a drug (a goal) can be enough to produce craving or lead to relapse.
In this project, we study Cacna1c rats in an established paradigm for Sign- and Goal-Tracking. As determined by a Pavlovian food-reward task, rats can be categorized into Sign- and Goal-Trackers, who respond differently to cue vs. reward presentation. Goal-Trackers typically approach a reward directly, Sign-Trackers first approach a reward-associated cue, even though it is not required for a reward access. They also behave differently to expectation violations, e.g. when consequences to their response to an outcome are suddenly changed.
We use this paradigm to investigate the role of external and internal (i.e. genetic, neuronal) factors and mechanisms in Sign- and Goal-Trackers. Furthermore, we aim to understand the neurochemical mechanisms underlying individual differences of rats. Western Blotting and HPLC are used to further understand the involvement of the brain structures.