Individual differences in pre-adolescent impulsivity, or the preference for smaller immediate rewards over larger delayed rewards, has been related to a multitude of outcomes measured later in life, such as physical and psychological health, substance dependence, financial well-being, academic achievement, social adjustment, and criminal behaviour. The mesocorticolimbic dopamine pathway (MCLP), a neural circuitry involved in reward motivated behaviours and decision-making, has been extensively linked to the delay discounting task, an effective tool for quantifying trait impulsivity. While previous research has demonstrated a negative correlation between the structural connectivity strength of the right dorsolateral prefrontal tract and the functional activity of striatum throughout development, the differences in tract strength within the MCLP and the relation to interindividual differences in impulsive behaviour in pre-adolescence has been understudied. The current study hypothesized that MCLP white fiber tract strength is related to interindividual differences of trait impulsivity in participants aged 9 to 12 years old. A probabilistic tractography approach, where every seed region voxel is sampled 1000 times for streamlines to the target of interest, was used to assess tract connectivity in a 58 X 58 whole-brain matrix. After correcting for multiple comparisons, the results demonstrated no significant correlations between white matter connectivity and individual differences in the delay discounting task. Given the small sample size and univariate approach, this large scale analysis was not sufficiently powered to detect any relationship between white matter and impulsivity. Future studies should apply further steps, such as correction for susceptibility induced distortions, to the constructed pipeline and investigate white matter differences with a variety of tensor metrics, such as fractional anisotropy and mean diffusivity.
Ghahari, Daamoon, "Individual Differences in Impulsivity and Mesocorticolimbic Connectivity Strength in Pre-adolescence" (2018). 2018 Undergraduate Awards. 16.