Functional MRI of food reward in food stimuli ranging in perceived healthiness

Although many people have the intention to eat healthy or to abstain from
eating unhealthy foods, people often find it difficult to put this into
practice. When someone is often not able to resist the temptation of unhealthy
foods this can result in weight gain and thus overweight or obesity on the long
term. Why is it so hard for people to make a healthy food choice and can the
neural response associated with the healthiness of food explain this? The brain
mechanisms involved in the regulation of food intake and the motivation to
consume or abstain from eating healthy or unhealthy foods are complex and yet
poorly understood.

Several brain structures, for example the basal ganglia, the insular cortex,
the prefrontal cortex, the hippocampus, the hypothalamus and the amygdala have
been shown to respond to presentation of food pictures. Previous studies showed
that individuals show different neural responses to visual presentation of
unhealthy (high energy/fat) versus healthy (low energy/fat) foods. A drawback
of the aforementioned studies is that the food categories healthy/unhealthy
differed in many characteristics. Therefore it is unknown whether it is the
difference in perceived healthiness that caused the differential neural
response or e.g. the difference in fat level, sugar level, or the tastiness of
the food.

In the study described here, we functional MRI is used to measure the brain
responses to pictures of packaged foods solely differing in perceived
healthiness. Perceived healthiness is modulated by means of packaging cues
while intrinsic properties of the food are kept constant. In addition to neural
activation, also behavioral reaction times and psychophysiological measures of
skin conductance, heart rate, and finger pulse amplitude are measured to
investigate the influence of perceived healthiness on these more indirect
measures of arousal and (autonomous) nervous system response.

Primary objective
1) To determine how modulating the perceived healthiness of a food alters the
neural response to pictures of food packages

Secondary objectives
1) To determine how modulating the perceived healthiness of a food alters the
skin conductance, the pulse amplitude and the heart rate response to pictures
of food packages
2) To determine how modulating the perceived healthiness of a food alters the
(behavioral) reaction time to pictures of food packages
3) To determine how modulating the perceived healthiness of a food alters the
following self-reported expected tastiness, and purchase intention

Randomized intervention study.
Upon arrival on the study day, subjects fill in a questionnaire on hunger and
satiety and date of last menstruation. Subsequently, subjects will undergo a 30
minute MRI scan. During the functional MRI scan subjects will carry out a food
choice task with pictures of food packages ranging in two levels of perceived
healthiness (healthy and unhealthy). During the task consecutively a picture of
a healthy and a unhealthy food package are presented and after that the subject
is asked to choose which of the two she would most like to eat now. After
leaving the scanner subjects again fill in a questionnaire on hunger and
satiety. After that, subjects will rate the pictures of food packages on
expected tastiness, perceived healthiness and purchase intention. At the end of
the study session, subjects receive and eat one of the foods chosen in the food
choice task.

MRI during the presentation of pictures.
Eating a cookie.

The intervention is non-therapeutic to the subjects. Subjects fast for three
hours before the investigation. Subjects are scanned for 30 minutes while
viewing pictures of food packages. This type of paradigm poses almost no risk.
Functional MRI is an invasive technique but the risks can be controlled.

Despite of the screening on claustrophobia it is possibly that subjects
experience claustrophobia symptoms during the MRI scan. However, this is very
rare in people that are scanned voluntarily (without medical neccesity).
In summary, the risk associated with participation is assessed as very low and
the burden as minimal.