Functional Connectivity Within the Gustatory Network Is Altered by Fat Content and Oral Fat Sensitivity – A Pilot Study

Abstract

Background: The amount of fat in ingested food dictates specific activation patterns in the brain, particularly in homeostatic and reward-related areas. Taste-specific brain activation changes have also been shown and the sensitivity to the oral perception of fat is associated with differential eating behavior and physiological parameters. The association between oral fat sensitivity and neuronal network functions has, however, not yet been defined. Objective: We aimed to investigate the association between fat-dependent neuronal functional connectivity patterns and oral fat sensitivity. Design: To investigate the underlying changes in network dynamics caused by fat intake, we measured resting-state functional connectivity in 11 normal-weight male participants before and after a high- vs. a low-fat meal on two separate study days. Oral fat sensitivity was also measured on both days. We used a high-resolution functional magnetic resonance imaging (MRI) sequence to measure any connectivity changes in networks with the seed in the brainstem (nucleus tractus solitarii, NTS), in homeostatic (hypothalamus) and in reward regions (ventral and dorsal striatum). Seed-based functional connectivity (FC) maps were analyzed using factorial analyses and correlation analyses with oral fat sensitivity were also performed. Results: Regardless of fat content, FC between NTS and reward and gustatory areas was lower after ingestion. Oral fat sensitivity was positively correlated with FC between homeostatic regions and limbic areas in the high-fat condition, but negatively correlated with FC between the dorsal striatum and somatosensory regions in the low-fat condition. Conclusion: Our results show the interaction of oral fat sensitivity with the network based neuronal processing of high- vs. low-fat meals. Variations in neuronal connectivity network patterns might therefore be a possible moderator of the association of oral fat sensitivity and eating behavior.

A systematic review of the biological mediators of fat taste and smell

“…Other clinical studies have examined the role of limbic and homeostatic regions in fat chemosensation. Frank-Podlech et al ( 58 ) observed a positive association between oral fat sensitivity and functional connectivity (FC) between homeostatic (hypothalamus) and limbic areas (hippocampus and amygdala) following a HFD. Conversely, they found a negative correlation between the FC between dorsal striatum and somatosensory regions following low-fat stimuli.…”

The effect of hunger state on hypothalamic functional connectivity in response to food cues

“…Functional coupling between the homeostatic regions of the brain and reward and taste processing areas was strengthened after a meal when evaluating HC in comparison to LC food cues. Concurrently, glucose, sucrose, and fat ingestion increased resting‐state functional connectivity of the hypothalamus to the striatum (Page et al, 2013 ) and insular cortex (Frank‐Podlech et al, 2019 ; Kilpatrick et al, 2014 ). In the current study, the hypothalamus network showed the greatest differences in functional coupling between the sated and the fasted state.…”

Investigation on taste characteristics and sensory perception of soft-boiled chicken during oral processing based on electronic tongue and electronic nose

“…Glumac et al [20] explored the in vitro simulation and oral processing of rapeseed oil (pure oil) and pork belly (fat food), found that saliva acted as an emulsifier, which could be an important mechanism for the oral processing of oil/fat. A large number of studies have been conducted on mouthfeel of oiliness, the release of fat in emulsion gel, fat content and preference differences [21][22][23][24] . Chicken skin, as a part of chicken, has relatively high fat content, and its role in chicken oral processing cannot be ignored.…”