Individual differences in structural-functional brain connections underlying curiosity

Curiosity motivates us to learn yet varies strikingly between individuals. This thesis aims to answer the following research questions: What are the brain networks associated with curiosity traits? How does curiosity benefit memory for information related and unrelated to the object of curiosity? How do curiosity traits and curiosity states interact to benefit memory? And how do variations in structural-functional brain connections relate to individual differences in curiosity-related memory? Chapters 2 and 3 investigate the neural mechanisms underlying trait curiosity, first examining its structural correlates followed by its functional correlates. In Chapter 2, inter-individual variations in the microstructure of the fornix related to Interest Epistemic Curiosity (EC), and inter-individual variation in the microstructure of the inferior longitudinal fasciculus related to both Interest and Deprivation EC. Furthermore, posterior hippocampal fornix microstructure was associated with Specific Perceptual Curiosity. These findings were not replicated in a follow-up experiment potentially due to several differences in the design. Next, Chapter 3 indicated that trait curiosity is associated with functional connectivity between the ventral tegmental area (VTA), hippocampus, and nucleus accumbens (NAcc); regions involved in the mesolimbic dopaminergic pathway. Chapter 4 transitions the focus of the thesis from trait curiosity to state curiosity, where states of high curiosity were found to predict later memory for trivia answers but not incidental information preceding curiosity elicitation. This chapter also suggests that trait curiosity does not interact with the positive effects of curiosity on later memory. Finally, a three-way relationship between white matter microstructure, resting-state functional connectivity and curiosity-related behaviours was examined. A mediation analysis revealed that functional communication between the VTA and NAcc mediates the relationship between fornix microstructure and curiosity-related memory benefit. Together, these results provide a better understanding into the underlying relationship between structural and functional connectivity in the brain and how they support curiosity-related behaviours