Relationships Among the Brain, the Digestive System, and Eating Behavior Workshop Summary (2015) / Chapter Skim
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5 Integrating the Evidence
5 Integrating the Evidence
Pages 85-96
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From page 85... ...
Box 5-1 highlights key points made by Rolls. FOOD REWARD, APPETITE, SATIETY, AND OBESITY1 Rolls hypothesized that obesity is related to an imbalance between the satiety and sensory-produced reward neural systems, with the latter overriding the former as a function of individual differences in cognitive control.
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From page 86... ...
Top-down cognitive control appears to be expressed in the same area of the brain as well. • In Rolls's view, given that humans are generally dominated by sensory inputs with high reward value, a key challenge for the food industry is to create highly palatable foods with low energy density.
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From page 87... ...
Sensory Signals and Reward Sensory neurons are highly selective. Rolls showed data illustrating the selectivity of a single taste neuron that responds to glucose sweetness but not to salt, sour, or water and that can even differentiate between glucose sweetness and fruit juice.
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From page 88... ...
In another human imaging study, de Araujo and Rolls (2004) observed significant representation of oral fat texture in the anterior cingulate cortex
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From page 89... ...
The researchers observed a greater brain response in the orbitofrontal cortex and pregenual cingulate cortex among individuals instructed to rate pleasantness, with the signal being linearly related to the pleasantness of the taste. When subjects were instructed to rate intensity, on the other hand, the researchers observed a greater response in the insular taste cortex, again with the signal being linearly related to the intensity of
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From page 90... ...
They found no difference between cravers and noncravers in the primary taste cortex, suggesting that whatever separates cravers from noncravers is not involved with sensory processing. However, there was a difference in the pregenual cingulate cortex, with chocolate in the mouth producing a much larger response in cravers than in noncravers in the ventral striatum, and the sight of chocolate producing a much larger response in cravers than in non ravers c in the pregenual cingulate cortex and orbitofrontal cortex.
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From page 91... ...
Rolls identified palatability and variety as two additional factors to consider when evaluating whether obesity may be related to overstimulation of the food reward system. Enhanced palatability in the human diet may lead to an imbalance between sensory reward and satiety signals, and enhanced variety may lead to increased food intake as a result of satiety's being partly sensory-specific.
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From page 92... ...
Mattes thinks this is an important point to address given that some people suggest there is a special quality about salt, fat, or sugar that may be driving eating behavior. Rolls replied, "The primary determinant of reward value is what comes into the mouth in tiny quantities." Based on sham feeding experiments with rats, animals show a preference for sucrose even when no food is reaching the gut.
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From page 93... ...
With every addictive substance, only a small percentage of people, 5 to 10 percent, become fully addicted. If the focus was only on that small percentage, the actual public health cost would not be captured in any way, especially for legal, cheap, easily accessible, and heavily advertised substances.
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From page 94... ...
Gastric banding, a purely restrictive procedure that does not involve rewiring the gastrointestinal tract, has not been associated with increased uptake of alcohol. The researchers in the cited study interpreted their findings to mean that gastric bypass patients, but not gastric banding patients, experience more rapid alcohol absorption and speculated that perhaps a more rapid rate of absorption provides greater reward.
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From page 95... ...
Avena replied that her work with rats has shown that animals actually are willing to inflict displeasure on themselves to get to M&Ms and other foods. But when restricted from sugar or highly palatable foods, they show behaviors suggesting that they are not happy.
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From page 96... ...
It is probably a relevant phenomenon to consider with food given the multiplicity of factors involved in eating behavior. In Rogers's opinion, a desire to eat chocolate probably is not overridden by concern that one may develop heart disease in 20 or 30 years.
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