Olfactory stimuli are known to have a significant effect on cognitive functions. However, their effect on risky decision-making remains unclear. The present study aimed to investigate this effect, using functional magnetic resonance imaging (fMRI) and a novel mixed gambling task.

Twenty-nine healthy participants with normal olfactory function underwent fMRI scanning while performing a gambling task under exposure to pleasant and unpleasant odors, as well as fresh air and a neutral condition without any olfactory stimulation. ROI-to-ROI functional connectivity analyses were conducted, focusing on regions involved in olfactory processing and risky decision-making, including dorsolateral prefrontal cortex (DLPFC), ventromedial prefrontal cortex (vmPFC), orbitofrontal cortex (OFC), insula, anterior cingulate cortex (ACC), piriform cortex, and uncus.

Pleasant odors, compared to the neutral condition, enhanced connectivity between OFC and vmPFC. Fresh air, compared to neutral, reduced connectivity between the DLPFC, OFC, vmPFC, piriform and insula, while increasing connectivity between the piriform and uncus. Unpleasant odors, compared to neutral, increased connectivity between the vmPFC, OFC, and ACC. Unpleasant odors, compared to fresh air, enhanced connectivity between the DLPFC and insula but reduced connectivity between the insula and OFC. Pleasant odors, compared to unpleasant odors, increased connectivity between the insula and OFC (p-FDR < 0.05).

Olfactory stimuli modulate neural networks underlying risky decision-making during a mixed gambling task. These findings highlight the clinical relevance of olfactory modulation for addiction research and the potential of functional connectivity analyses to provide a foundation for personalised interventions aimed at reducing maladaptive risk-taking behavior and cue-driven vulnerability.