Increased Subjective Distaste and Altered Insula Activity to Umami Tastant in Patients with Bulimia Nervosa

Abstract

The aim of this study was to examine differences in brain neural activation in response to monosodium glutamate (MSG), the representative component of umami, between patients with bulimia nervosa (BN) and healthy women (HW) controls. We analyzed brain activity after ingestion of an MSG solution using functional magnetic resonance imaging (fMRI) in a group of women with BN (n = 18) and a group of HW participants (n = 18). Both groups also provided a subjective assessment of the MSG solution via a numerical rating scale. The BN group subjectively rated the MSG solution lower in pleasantness and liking than the control group, although no difference in subjective intensity was noted. The fMRI results demonstrated greater activation of the right insula in the BN group versus the control group. Compared with the HW controls, the BN patients demonstrated both altered taste perception-related brain activity and more negative hedonic scores in response to MSG stimuli. Different hedonic evaluation, expressed as the relative low pleasing taste of umami tastant and associated with altered insula function, may explain disturbed eating behaviors, including the imbalance in food choices, in BN patients.

Gastrointestinal Interoception in Eating Disorders: Charting a New Path

“…Neuroimaging studies have shown anatomical alterations in women with eating disorders in brain regions centrally involved in taste and its valuation (e.g., medial orbitofrontal cortex, insula, striatum) [102]. Prior findings also suggest that women with acute restricting-type AN [103] and those recovered from AN or BN show aberrant anterior insula responses to sucralose [104,105]. Women with restricting-type AN display a reduced ability to discriminate between sucrose, artificial saliva, or no solution, compared to healthy women and to women recovered from AN [106].…”

The Neurobiology of Eating Disorders

“…83 In studies on binge eating, bitter taste led to higher medial prefrontal electroencephalography signal, or umami taste, more strongly activated the insula in BN, whereas hedonic ratings were lower. 84,85 Cognition During a reversal learning task involving positive and negative feedback, participants with AN changed behavior strategy more frequently after negative feedback, related to cingulate activation. 86 During the Wisconsin Card Sorting Test for cognitive flexibility, participants with AN had higher activation during behavior change in the frontal, parietal, and occipital regions but lower activation during learning or maintaining rulebased behavior.…”

The neurobiological reward system and binge eating: A critical systematic review of neuroimaging studies

“…Opposite to HC, they had a larger response to sucrose than to a bitter stimulus in the left dlPFC, brainstem, OFC, and right postcentral gyrus (Monteleone et al, 2017). But after giving an umami stimulus, patients with BN reported lower liking scores and displayed more activity of the right middle insula and ACC (Setsu et al, 2017). Of the four studies that used a reward task, there were two (50%) that used a MID or FID, one (25%) that used a reward‐guessing task, and one (25%) that used a spatial learning task where participants needed to navigate a maze in order to find rewards.…”

“…Opposite to HC, they had a larger response to sucrose than to a bitter stimulus in the left dlPFC, brainstem, OFC, and right postcentral gyrus (Monteleone et al, 2017). But after giving an umami stimulus, patients with BN reported lower liking scores and displayed more activity of the right middle insula and ACC (Setsu et al, 2017).…”