MRI-compatible device for stimulating chemical senses in humans and capturing subject feedback

Abstract

fMRI (functional magnetic resonance imaging) is a method that allows brain activity to be visualized while a subject lies in the scanner performing tasks. The strategy consists of detecting the brain regions that are activated by this stimulation from a sequence of images of the brain. To conduct these original experiments, our team developed a chemical sense stimulator compatible with the intense magnetic environment of MRI (Magnetic Resonance Imaging) scanners. This article describes the design of this stimulator, the manufacture of the stimulator tip through which the various liquid solutions flow, the choice made for delivering the different solutions, and how the whole system is controlled so that it is synchronized with the tasks requested of the subject. Part of the article deals with the metrological validation of the stimulator. Finally, the article shares expertise in the creation of a paradigm implementing our stimulator as part of the PleasIn research project PleasIn (Métaprogram DID’IT: Diet Impact and determinants – interactions and transitions), whose objective was to understand the effect of choice on pleasure (or rather subjective value) induced by the consumption of pleasant-tasting beverages.