AFFECT MODULATES APPETITE -RELATED BRAIN ACTIVITY TO IMAGES OF FOOD

KILLGORE, W. & YURGELUN-TODD, D. (2006)

VIVIEN CHIU

Are you a Carbohydrate Craver?

Introduction

Thorough studies done in labs on animals, but what about us?

Higher order regions of cerebral cortex involved in humans

What is Affect? Conscious subjective feeling/emotion, interaction with stimuli

OBJECTIVE: To determine if cerebral activity would covary with affect ratings and if covariance pattern would differ as a function of food’s nutritional content

Brain Regions

Insular cortex Ongoing status of

internal state

Responds directly to specific taste stimuli changes (salty/sweet)

Increased activation during hunger/smell of food

Orbitofrontal cortices Gathers info to

converge them and evaluate overall reward potential

Medial/caudal: Heightened activity with motivation to eat

Lateral: inhibitory function related to satiety

Methods

Participants 13 healthy (mean BMI = 22.1 kg/m2 ) women, ranging

from 21-28 years old

Imaging Methods Over 20 contiguous coronal slices were used to collect

images from blood oxygen level dependent (BOLD) fMRI

Each scan lasted 150s, with 50 images collected each time

Methods

Stimulation Three separate scanning runs:

lasted 150s each 5 alternating 30s periods with control and stimulus 10 pictures per period

Low-fat/calorie-lean foods

High-fat/calorie-dense foods

Non-edible food related objects

Methods

PANAS (Positive and Negative Effect Schedule) PA

Pleasant enthusiasm Active positive

engagement NA

Subjective distress Unpleasant emotional

activation

Results

Results Summary

High Calorie Foods PA with greater BOLD

activity in right lateral orbitofrontal cortex

Higher NA ratings were associated with greater BOLD activity within medial regions of orbitofrontal cortex/ posterior insula

Low Calorie Foods Greater PA seen in

with increase of BOLD activity from orbitofrontal cortex

Higher NA associated with increased BOLD activity in right lateral and anterior insula (might be difference between anterior and posterior)

Discussion

Responsiveness/feeding related regions of brain were significantly related to PANAS ratings Medial orbitofrontal rewarding stimuli Lateral orbitofrontal punishing stimuli/inhibition of

stimuli responseProposed mechanism

Relation between mood and appetite involve changes in activity of orbitofrontal cortices Negative mood/stress increased cravings “Self-medicate” high carbs = increasing serotonin

Conclusions

Opinion on paper Strengths:

Implications for people with seasonal affective disorder or bipolar depression

Underlying message about food choice Limitations:

fMRI in-plane distortion Small sample of only females in a limited age range

working at the same hospital in Massachusetts Correlation does not mean causation

Next steps? Specifically correlating individual food cravings

Summary

Affective state influences brain activity in response to food of varying calorie density/fat content Negative mood

Unhealthy food choice association shun low-calorie, low-fat

Positive mood Fewer cravings for foods high in calorie/fat content

Neurobiological mechanism may be involved between mood and food choice Right lateral medial cortex: Reduced motivation to eat Medial orbitofrontal/insular cortices: Increased desire

to eat

Questions?

Don’t be an emotional eater, be AWESOME instead