White matter integrity predicts domain-specific risk perception: Insights from diffusion tensor imaging

Diffusion tensor imaging (DTI) noninvasively assesses the macroscopic organization of white matter (WM) brain tissue. Measures of fiber directionality can be quanitified, visualized, and anatomically mapped (Mukherjee et al., 2008). Behavioural and personality correlates of specified fiber pathways have been shown recently. Novelty seeking and reward dependence are linked to dissociable connectivity streams (Cohen et al., 2009) and neuroticism, openness and agreeableness are associated with WM integrity (Xu and Potenza, 2012). We expected WM integrity in frontostriatal pathways to correlate with risk perception parameters. As striatal activity is highly influenced by prefrontal input, risk perception could be linked to fiber density. DTI of 42 subjects (mean age 29.86 yrs, 17 male) were acquired on a 3.0 T Siemens Trio with 60 gradient directions (resolution: 1.7×1.7×1.7mm). Probabilistic tractography was used to generate fiber tracts from striatum to dorsolateral prefrontal cortex (DLPFC), lateral and medial orbitofrontal cortex (LOFC, MOFC). Within these tracts, several measures were extracted for each individual: longitudinal (λ1) and transversal diffusivity (λt=λ2 + λ3 / 2), mean diffusitivity (MD) and fractional anisotropy (FA). Mean tracts were generated thresholded at 0.75 for each individual which overlapped in at least 10 subjects in the sample. Behavioural data were obtained using an online survey on domain-specific risk-taking (Weber, Blais and Betz, 2002). Domains include ethical, financial, health/security, recreational and social items. Partial correlation analyses were performed controlling for age and numeracy. Greater diffusion in several striatal-prefrontal tracts was related to higher risk perception in ethical and financial domains. Lower right longitudinal diffusion predicts higher social risk perception. This is preliminary evidence, that WM integrity seems to have lateralized effects on domain-specific risk perception.

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