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NutrInsight • Satiety: News Insights
Fatty acid-induced gut-brain signalling and sad emotions
fMRI has been used recently to investigate the interactions between signalling initiated by stimuli in the gut and exteroceptively generated emotions [Van Oudenhove et al., 2011]. Healthy adults received an intra-gastric infusion of fatty acid solution or saline during neutral or sad emotion induction by musical and visual cues. They rated their sensations of hunger, fullness, and mood. Figure 3 shows activation in brain regions in which a significant fat-by-emotion interaction effect was revealed by the blood oxygen level-dependent signal (BOLD). While fatty acid infusions increased the BOLD response under neutral emotion conditions, compared to saline infusions, they attenuated sad emotions expressed both in the behavioural ratings of mood and at the level of neural activity.
Figure 3: (A) Brain regions of interest in which a significant fat-by-emotion interaction effect was found.
(B) and (C) Bold Signal Change (30 min AuC) for each condition in mid-cingulate cortex and left hypothalamus.
A significant fat-by emotion interaction effect on the BOLD signal was found: fatty acid attenuates the effect of sad emotion compared with saline. AUC: area under the curve; BOLD: blood oxygen level-dependent signal.
** p<0.01, ***p <0.001 versus fat neutral; # p<0.001, ## p<0.01 versus saline sad.
Source: Adapted from Van Oudenhove et al., 2011
5.4 Top-down control of appetitive behaviour by cognition and emotion
While nutrient-associated signals from the internal milieu can affect emotions and the learning of food reward, cognitive and affective factors resulting from the activity of higher brain structures can also affect sensory perception and responses of the periphery of the organism. Again, fRMI has provided examples of such “top-bottom” control of appetitive behaviours.
Marketing actions, such as changes in the price of a product, can affect neural representations of experienced pleasantness. For example, the subjective appreciation of the taste of wine can be influenced by knowledge about its cost. A study using fRMI scanned human subjects while they sampled different wines. The same wine labelled as expensive was rated more pleasant than when labelled cheap, and the neural correlate consisted of a much stronger and longer activation in the medial orbitofrontal cortex [Plassman et al., 2008]. Top-down cognitive processes encoding flavor expectancies are integrated in the medial orbitofrontal cortex.
(A)
(B) Mid-cingulate cortex
saline fat
Cingulate Cortex
Hypothalamus
Brainstem
fat
saline
neutral
neutral sad sad
Od
(UCS) devaluation
(C) Left hypothalamus
fat saline fat
or pleasantness
saline
neutral neutral sad sad
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Bold Signal Change Bold Signal Change (30 min AUC) (30 min AUC)
Bold Signal Change (30 min AUC)