White-Matter Tract Connecting Anterior Insula to Nucleus Accumbens Correlates with Reduced Preference for Positively Skewed Gambles

Neuron. 2016 Jan 6;89(1):63-9. doi: 10.1016/j.neuron.2015.12.015.

Abstract

Individuals sometimes show inconsistent risk preferences, including excessive attraction to gambles featuring small chances of winning large amounts (called "positively skewed" gambles). While functional neuroimaging research indicates that nucleus accumbens (NAcc) and anterior insula (AIns) activity inversely predict risky choice, structural connections between these regions have not been described in humans. By combining diffusion-weighted MRI with tractography, we identified the anatomical trajectory of white-matter tracts projecting from the AIns to the NAcc and statistically validated these tracts using Linear Fascicle Evaluation (LiFE) and virtual lesions. Coherence of the right AIns-NAcc tract correlated with reduced preferences for positively skewed gambles. Further, diminished NAcc activity during gamble presentation mediated the association between tract structure and choice. These results identify an unreported tract connecting the AIns to the NAcc in humans and support the notion that structural connections can alter behavior by influencing brain activity as individuals weigh uncertain gains against uncertain losses.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Mapping
  • Cerebral Cortex / physiology
  • Choice Behavior / physiology*
  • Diffusion Magnetic Resonance Imaging / methods
  • Diffusion Tensor Imaging / methods
  • Female
  • Gambling*
  • Humans
  • Male
  • Middle Aged
  • Nucleus Accumbens / physiology*
  • White Matter / physiology*
  • Young Adult