How is salt taste intensity encoded within the human brain? The responses of BOLD fMRI using food models

Functional MRI (fMRI) allows understanding the mechanisms by which sensations induced by food cues are perceived and processed within the brain, under the influence of various external (e.g. visual stimuli) and internal factors (e.g. body state). In particular, it allows analyzing at neurophysiological level how food formulations influence their sensory qualities and the pleasure experienced. Here, we used fMRI to infer several neural correlates of the perceived salty intensity produced by rewarding food models. Subjects received different savory solutions on their tongue using an MR-compatible gustatometer. The activations were mapped from smoothed high-resolution data, an imaging protocol providing good functional sensitivity in the gustatory cortex [1]. Two primary areas for taste processing were presumed in the human brain, intercepting the operculo-insular cortex and the lesser-known postcentral gyrus. We found highly significant neural correlates of salt taste intensity at the base of the postcentral gyrus bilaterally and to a lesser extent in the insula and the overlying operculi. This finding suggests that both primary areas were involved in salt taste intensity coding in human brain, which contrasts with previous results obtained with unpleasant salty solutions. We speculate that it may result from the use of rewarding food models, making it necessary to take specific account of the stimulation context for mimicking the brain’s integration of sensory rewards during normal feeding.[1] Iranpour J, Morrot G, Claise B, Jean B, Bonny J-M. Using high resolution to improve BOLD fMRI detection in gustatory cortices. Human Brain Mapping. Submitted