Social learning about rewards - how information from others helps to adapt to changing environment : PhD thesis

Winiarski, Maciej

Skip to main menu
Skip to search engine
Skip to content
Skip to footer

Social learning about rewards - how information from others helps to adapt to changing environment : PhD thesis

Download

Description
Information

Title: Social learning about rewards - how information from others helps to adapt to changing environment : PhD thesis

Abstract:

Relationships between individuals that make up a group develop through a series of social behaviors, such as establishing hierarchies and forming bonds. Social learning, or the ability to gain information from the behavior of other individuals, is one of the most essential elements of the social behavioral repertoire of mammals. The presented dissertation describes the development of experimental protocols for evaluating social learning in groups of mice tested under semi-natural conditions. For this purpose, the Eco-HAB system was used. The Eco-HAB reflects the most important features of the mice's natural environment, while allowing fully automated evaluation of social behavior. The developed protocols were then used to study how information about the location of rewards in the environment spreads among individuals in the group, and how social relationships in the group, including the social network, affects responses to social information about food. It was discovered that mice have the ability to effectively learn about rewards found in the environment by other familiar individuals based on the scent traces the conspecifics leave behind, without the need for direct contact with group members. In addition, it was discovered that the effectiveness of social learning depends on the social hierarchy and structure of the social network. Namely, individuals that are the centers of the network, show the most intense response to social stimuli associated with reward. What is more, a pioneering way to study the above-described parameters in a new habitat (inter- environmental transfer of social information) previously populated only by "scout" mice was also developed. The creation of the aforementioned experimental protocols made it possible to conduct research on the neural mechanisms of social learning. The second part of this dissertation describes studies on the importance of neuronal plasticity in the prelimbic part of the prefrontal cortex for the ability to learn socially from group members. For this purpose, specially designed nanoparticles containing TIMP1 (Tissue Inhibitor of Metalloproteinases 1), an inhibitor of the enzyme MMP9 (Matrix Metallopeptidase 9) which is key for synaptic plasticity, were used. MMP9 in the brain is involved in the formation of neural connections by regulating the maturation of dendritic spines. In addition, numerous studies show that, at the behavioral level, manipulation of MMP9 activity affects learning and memory consolidation. The nanoparticles used in this study, when injected into the brain, gradually release their contents, which made it possible to manipulate neuronal plasticity over a long period of time, and thus observe behavioral effects over many days. Over the course of the study, it was shown that the ability of mice to transmit information and learn the location of a potential reward based on the odor traces left in the environment depends on the undisturbed activity of MMP9 protein in the prelimbic part of the prefrontal cortex. It was discovered that reducing the level of MMP9 protein activity with its inhibitor TIMP1 decreases reward-seeking motivation in response to socially transmitted reward information. Moreover, the described manipulation of neuronal plasticity has been shown to interfere with the animals' ability to use social information in novel environments. It also resulted in significant remodeling of the social networks and, consequently, the in-group social interactions. The findings of the presented study are a significant contribution to the development of knowledge about social learning and the underlying neuronal mechanisms. In particular, the development of new experimental protocols contributes to the versatility of the Eco-HAB, the automated system for tracking social behavior developed at the Nencki Institute.