Neural Correlates of Sensory Specific Satiety

Sensory specific satiety, or the phenomenon that the pleasantness of a particular taste declines when certain types food are consumed to satiety, plays an important role in food choice and meal termination. Since changes in taste, smell and appetite are commonly observed in obesity, previous studies investigated the relation of sensory specific satiety to weight gain, but observed conflicting results. To gain a more detailed understanding of the relationship between sensory specific satiety and weight homeostasis, we will examine the rewarding effect of sugar in a group of 30 healthy participants with a body mass index ranging from 17.5 to 35kg/m2. We will employ a gustatory stimulation paradigm designed to induce sensory specific satiety for glucose. During fMRI scanning, glucose and water are applied orally using a gustometer. Furthermore, relevant hormonal satiety parameters are measured, as well as dietary behavior and food preferences in everyday life. This will allow us to assess neuronal stimulus processing in relation to the sensory satiety level and to investigate the relationship with everyday eating behavior. A better understanding of factors contributing to the development and maintenance of overweight are crucial for the development of new treatment options for obesity.

Primary outcomes

• Choice of water compared to choice of sugar during Sensory Specific Satiety. [1 hour]: Comparing tasting of water with tasting of sugar (G10%) when participants are allowed to freely chose between the two during specific satiety for sugar.
• Choice of water compared to passive ingestion of 20% sugar solution during Sensory Specific Satiety. [1 hour]: Comparison of voluntary tasting of water with the "forced" tasting of sugar during specific satiety for sugar.

Secondary outcomes

• Influence of variations in BMI on brain activation during Sensory Specific Satiety. [1 hour]

Sex: All, ages: 18 Years to 55 Years

Inclusion Criteria:

1. BMI between 17,5 and 35 kg/m².
2. Over age of 18 years.
3. Right-handedness.
4. Normal or corrected-to-normal vision.
5. Capacity to consent.

Exclusion Criteria:

1. History of head injury or surgery.
2. History of neurological disorder.
3. Severe psychiatric comorbidity.
4. Lifetime or current medical illness that could potentially affect appetite or weight (including eating disorders diagnosis)
5. Smoking.
6. Current psychotropic medication.
7. Inability to undergo fMRI scan (e.g. metallic implants, claustrophobia, pacemakers).
8. Pregnancy.

• joe simon, Ph.D., Principal investigator, Heidelberg University