1. Episodic Memory and
Appetite Regulation In
Humans
Study Authors:
Jeffrey F. Brunstrom, Jeremy F. Burn, Nicola R. Sell, Jane M.
Collinwood, Peter J. Rogers, Laura L.Wilkinson,
Elanor C. Hinton,Oliva M. Maynard, & Danielle Ferriday
Presenter’s name: Emily Seferovich
2. Study Objective and Design
• Hypothesis: Memory manipulation might influence post-meal hunger and fullness
and, in turn, bias the “expected satiation” of a fixed portion of soup 24-hours later
• Objective:To observe and highlight the potentially important role for episodic
memory in the control of meal size and appetite regulation in humans.
• Design: Participants were tested in a Between Subject-Design
• Conditions:
• 1) See 300mL, eat 300mL (Condition 1)
• 2) See 300mL, eat 500mL (Condition 2)
• 3) See 500mL, eat 500mL (Condition 3)
• 4) See 500mL, eat 300mL (Condition 4)
3. About the Participants:
• 100 total participants (69 female, 31 male)
• 22 overweight, 5 obese, 73 normal weight.
• Mean BMI=23.4 (SD=3.46)
• Individuals with specialized diet needs were excluded
(vegetarian/vegan diets & individuals with food allergies)
• All volunteers were students/faculty of the University of
Bristol (SW England), recruited via email.
5. Procedure:
• Step 1: Participants were set to attend 2 test sessions (roughly 24-hours apart)
• Step 2: (Session 1) Participants’ hunger and fullness assessed via visual-analogue scales (criteria
ranging from “no hunger” to “extremely hungry”).
• Step 3: Based upon the results of the satiety forum, participants were distributed into one of the
four Conditions
• Step 4: Participants of each condition were provided with soup and a volume-adjustable soup
bowl apparatus (as previously shown)
• Step 5: Post-meal satiety was gauged again, Participants given 3 hunger and fullness rating scales
(1/hr).
• Step 6: 24 hours later, participants shown a bowl containing 400 mL soup, evaluated its Expected
Satiation, then completed the DEBQ.
• Step 7: Patients given the opportunity guess the purpose of the study and to indicate whether or
not they perceived the soup volumes to have been manipulated.
6. Hippocampal Memory
• The hippocampus is a 2-pronged region of the medial-
temporal lobe of the brain.
• Key in the formation of episodic memories
• Recent research indicates that the Hippocampus is home to
some insulin and leptin receptors
7. Data: Baseline and participant characteristics.
Brunstrom JM, Burn JF, Sell NR, Collingwood JM, et al. (2012) Episodic Memory and Appetite Regulation in Humans. PLoS ONE 7(12): e50707.
doi:10.1371/journal.pone.0050707
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050707
8. Figure 2. Estimated marginal means (+/− SEM) for hunger ratings (0–100 mm) taken 0, 60, 120, and 180
minutes after consuming the soup.
Brunstrom JM, Burn JF, Sell NR, Collingwood JM, et al. (2012) Episodic Memory and Appetite Regulation in Humans. PLoS ONE 7(12): e50707.
doi:10.1371/journal.pone.0050707
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050707
9. Data: expected satiation scores.
Brunstrom JM, Burn JF, Sell NR, Collingwood JM, et al. (2012) Episodic Memory and Appetite Regulation in Humans. PLoS ONE 7(12): e50707.
doi:10.1371/journal.pone.0050707
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050707
10. Data: Portion size estimates (ml) from participants who saw
300 ml or 500 ml of soup.
Brunstrom JM, Burn JF, Sell NR, Collingwood JM, et al. (2012) Episodic Memory and Appetite Regulation in Humans. PLoS ONE 7(12): e50707.
doi:10.1371/journal.pone.0050707
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050707
11. Study Conclusions:
• Participants who initially saw a smaller portion of soup (day 1) went on to
expect the 400 mL portion to be relatively less satiating (day 2).
• Participants who initially saw a larger portion of soup (day 1) went on to
expect the 400 mL portion to be relatively more satiating (day 2)
• 2&3 hrs. post meal, hunger was no longer predicted by the actual amount
consumed, regardless of serving size.
• Differences in hunger related to the perceived
amount at the beginning of the meal.
• Satiety is influenced by memory for a recently
consumed meal
By exploring the interaction between actual and remembered amounts of soup, the researchers sought to quantify the respective contribution to hunger and fullness over a 3Hr period
Additionally, a second objective was to establish the extent to which memory manipulation impacts beliefs about the soup (this was tested at a subsequent session).
Expected satiation (“the extent to which a given food is expected to deliver satiation as compared to another food on a calorie-for-calorie basis”) is an excellent predicting factor of the energy content of self-selected meals.
STEP 3:
Just a reminder, the conditions were:
1) See 300mL, eat 300mL (Condition 1)
2) See 300mL, eat 500mL (Condition 2)
3) See 500mL, eat 500mL (Condition 3)
4) See 500mL, eat 300mL (Condition 4)
In order to avoid clumping hungry participants with hungry patients and/or full patients with full patients, a minimisation method was employed that introduced a 4:1 element of chance for participant grouping.
STEP 4: Participants were required to stop eating the soup when the volume hit a 100mL mark, which obscured the base of the bowl from view.
STEP 5: Participants were also provided with a buzzer to notify them when to fill out the scales. The participants were required to avoid food and/or caloric beverages entirely. ***Allowance for H20 and/or calorie free beverages is a potential weakness in this study.
STEP 6: DEBQ stands for Dutch Eating Behavior Questionnaire, which is an effective tool to determine a subject’s involvement with dietary restraint, external eating, and emotional eating.
Episodic memories are based upon and derived from experiences we have (aka not procedural memory).
Damage to the hippocampal region often times manifests itself in a decreased capacity to form and retain new experienced-based memory.
The sheer fact alone that the hippocampus memory center contains satiety-related hormone receptors is a foundation for the study.
“See 300 eat 500” had the highest level of satiety out of all the groups, BUT
“See 500 eat 300” had a relatively comparable satiety score to the “see 300 eat 500” group, indicating that perception influences satiety!
This table shows results of the 3hr post meal surveys:
The graph illustrates the effect of soup-volume perception on hunger levels (individuals who initially saw larger soup volumes reported significantly lower hunger levels over the 3 hour period)
Results of the Day 2 test, where participants were shown the 400mL soup bowl.
Participants who (on day 1) saw 300 mL ranked the expected satiation level SIGNIFICANTLY lower than those participants who (on day 1) initially saw a 500mL bowl of soup.
This is how much soup, on average, conditions 1&2 estimates were in the 400mL bowl versus conditions 3&4.
This clearly represents that the perceived satiety of the previous day GREATLY influenced the Expected Satiation level of the observed bowl.
As pertaining to bullets 1 and 2: This is critical, because it shows that memory was differentially influenced by manipulation of the soup volume.
In other words, someone who had less food day 1 was more likely to think a 400mL bowl of soup would be less satisfying on day 2, even though 400 mL was more than they were served on day 1.
This can lead to excessive calorie intake in individuals who recall certain portions to leave them feeling hungry- it may push them to overcompensate for the feelings they remember from previous eating experiences.
