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PSYC 2410 Lecture Notes - Milkshake, Reward System, Blood Sugar

Course Code
PSYC 2410
Dan Meegan

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Chapter 10
CCK - peptide tells brain “no need to eat anymore”
homeostatic energy regulation (energy in=energy out)
Overeating (energy in > energy out)
Factors causing overeating : (see lecture slide)
Evolved to Eat
For many people/animals, food is not always available when energy is low
if energy dips below a certain level either use bodily stores or eat
we are motivated to eat
Evolution: motivation to eat when food is available, regardless of internal energy state
Mere sight/smell of food > drop in blood glucose > hunger/eating
The `Reward’ System brain system that makes eating (& other behaviors) pleasurable
Parkinson’s – dopamine
Can override homeostatic energy regulation
Many possible contributing factors (see slide)
Ex: dysfunctional reward system
Fewer dopamine receptors in obese people
More obese = fewer dopamine receptors = more eating
fMRI while drinking milkshake: reduced activity in reward system for obese people
less likely to receive the pleasure theyre looking for = less likely to stop
Obesity: dysfunctional reward system?
Hypothesis: when dopamine is deficient, more eating Is required to get reward
How do obese adults become dopamine deficient? Nature vs. Nurture
Overeating > dopamine deficiency
Evidence? Sustained consumption of fats or sugars > neurochemical changes to reward system
Treatment? Treat ALL children; overeating prevention
Addiction food, drugs, gambling, etc.
Pleasure mediated by reward system
Chronic use/abuse leads to neurochemical changes
Other Applications appetite stimulation/suppression
Why does cannabis stimulate appetite?
The Endocannabinoid System
Cannabinoid (CB) receptors are widely distributed in the brain, including the reward system
(nucleus accumbens, NA)
Animals find chemicals in cannabis ‘disgusting’ > defense factor – animals avoid it because they
don’t want to feel the way they do
CBs administered directly to NA induce pleasure
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