1 Across the lifespan, curiosity motivates us to learn, yet curiosity varies strikingly between 2 individuals. Such individual differences have been shown for two distinct dimensions of 3 curiosity: epistemic curiosity (EC), the desire to acquire knowledge about facts, and 4 perceptual curiosity (PC), the desire for sensory information. It is not known, however, 5 whether both dimensions of curiosity depend on different brain networks and whether inter-6 individual differences in curiosity depend on variation in anatomical connectivity within these 7 networks. Here, we investigated the neuroanatomical connections underpinning individual 8 variation in trait curiosity. Fifty-one female participants underwent a two-shell diffusion MRI 9 sequence and completed questionnaires measuring EC and PC. Using deterministic 10 spherical deconvolution tractography we extracted microstructural metrics (fractional 11 anisotropy (FA) and mean diffusivity (MD)) from two key white matter tracts: the fornix 12 (implicated in novelty processing, exploration, information seeking and episodic memory) 13 and the inferior longitudinal fasciculus (ILF) (implicated in semantic learning and memory). In 14 line with our predictions, we found that EC -but not PC -correlated with ILF microstructure.
15Fornix microstructure, in contrast, correlated with both EC and PC with posterior 16 hippocampal fornix fibres -associated with posterior hippocampal network connectivity -17 linked to PC specifically. These findings suggest that differences in distinct dimensions of 18 curiosity map systematically onto specific white matter tracts underlying well characterized 19 brain networks. Furthermore, the results pave the way to study the anatomical substrates of 20 inter-individual differences in dimensions of trait curiosity that motivate the learning of 21 distinct forms of knowledge and skills.
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Significance statement
23Despite recent interest in curiosity states and the broad spectrum of variation in stable 24 tendencies to experience or express curiosity, the biological correlates of trait curiosity are 25 unknown. Here, we found that specific types of curiosity correlate with microstructure of 26 specific white matter tracts in the brain -the inferior longitudinal fasciculus and the fornix.
27Our findings on the relationship between specific aspects of curiosity and anatomical 28 connections underlying well characterized brain networks highlight the specificity of trait 29 curiosity. Furthermore, our findings pave the way to further understand inter-individual 30 differences in curiosity and which aspects of curiosity benefit language, memory and other 31 cognitive processes cultivating a deeper knowledge and skill set. 32 4 Introduction
33Curiosity is described as the desire for new information that motivates seeking out and 34 acquiring knowledge (Loewenstein, 1994; Litman, 2005). The momentary experience of 35 curiosity can be seen as a motivational state that facilitates knowledge acquisition (Silvia & 36 Kashdan, 2009; Gottlieb and Oudeyer,...