Observational Learning: Examining Behavioral Repertoires and the Effects of Genetics and Environmental Enrichment

Abstract

Observational learning allows for the acquisition of novel information, behaviors, and even fears in the absence of explicit instruction, thus reducing the time needed for direct instruction. This type of learning is essential for acquiring an understanding of implicit social norms and cultural customs. This thesis examines the effects of experience and genetics on observational learning, as well as the behavioral repertoires expressed after observational learning. To ensure that mice can be reliably observationally fear conditioned, we tested freezing as a metric of observational fear conditioning, as well as the effect of experimenter on this metric. We found that not only could mice be fear conditioned through observation, but also that the experimenter did not affect observational learning. We used environmental enrichment to analyze how enrichment alters the robustness of observational learning. We hypothesized that the mice who were environmentally enriched would show enhanced observational fear conditioning compared to unenriched mice, and would thus exhibit elevated fear behaviors. This would corroborate past research that found that social enrichment and physical activity improved learning, memory and cognition. Contrary to this prediction, we found that enriched mice are not significantly differ in freezing time compared to unenriched mice. This thesis also examined how genetics, more specifically autism, affects the transmission of observational learning. Past research has shown that people with autism (ASD) show deficiencies in the necessary skills for observational learning. Thus, we hypothesized that the autism model strains would exhibit a decrease in observational learning. To test this hypothesis, we used two genetic autism mouse model strains, Cntnap2 and Tsc1. These strains were chosen because they both have genetic mutations involving the cerebellum, a brain region known to be connected to autism. To analyze the nature of fear expressing behaviors in observer mice, this thesis also investigated the flexible defensive behavioral repertoire mice express after undergoing observational fear conditioning. Flexible defensive behavior analysis is built upon the idea that proximity to the threat, both in terms of distance and perceived safety, inherently changes the expression of fear. This suggests that undergoing observational, instead of direct, fear conditioning, would change the way mice interact with the fear-inducing conditioned stimulus. Furthermore, this would suggest that freezing may not be the most reliable or the most appropriate measure of observational fear conditioning. Following this logic, we tested the preferences for hiding and vigilance activity, with the hypothesis that the observers would display these activities more than the demonstrator and control groups. We found that the observer mouse did not significantly hide or display vigilance activity more than either experimental group.