Psyc417 Hunger
Last updated: 1/9/2025
Questions
What is the hunger signal? <details> </details> What is lipoprivic eating? <details>Lipo-fat, privic- deprived, so eating when we are on a high fat diet</details> What is glucoprivic eating? What causes regular eating? <details>Hunger seems to be an anticipatory motivation so that we maintain energy homesotasis.</details> Why is it difficult to study good intake in a lab setting? <details>The natural environment plays a role in eating.</details> What is the dorsal vagal complex? What is the difference between homeostatic and non-homeostatic eating? What brain regions are involved in homeostatic and non-homeostatic eating? <details> homeostatic: dorsal vagal complex non-homeostatic: hypothalamic or forebrain regions.
</details> ## Notes ##### Proposed hunger signals **Lipostatic set-point**: when a certain concentration of fatty acid gets too low we get hungry) and too high we will get satiated. For example, when an animal is given mercaptoacetate (an inhibitor of fatty avid oxidation), can induce eating when they are on a high-fat diet. **Thermostatic set-point**: reduction in body temperature stimulates eating so that temperature increases. This is not a good signal because before we start eating, our body temperature increases instead of decreases. **Glucostatic set-point**: decreased glucose utilization stimulates eating behavior. This happens when 2-deoxy-D-glucose cannot be metabolized to generate energy. This causes hyperglycemia. This can only happen when the amount of 2-DG is so high that the cells cannot get any glucose, so this is likely an emergency response.None of these hunger signals explain regular eating, so they might play a part, but not the majority of the story!
Energy homeostasis
Insulin causes glucose to convert into glycogen Glucagon causes glycogen to convert into glucose
These two hormones allow for blood-glucose levels to be stable, and help lower blood-glucose level after a meal.
Motivated behavior
Appetitive behaviors: behaviors that bring animals in close contact with their goals. It is instrumental behavior, or an operant response to gain access to the goal. Consummatory behaviors: behaviors that complete specific goals. They are usually fixed patterns. For eating, this is consumption.
Consummatory behaviors are usually in the hindbrain because they are so simple. For eating, this is in the reticular formation, which is the brain region that has to do with patterns of movement.
There is also non-homeostatic eating, such as being bored, or social cues.
Homeostatic eating is direct control mechanism. It has to do with maintaining homeostasis, and is regulated by your hind brain and receives signals such as the release of GI peptides.
Non-homeostatic eating is your brain causing you to eat or not to eat (i.e. food tastes really really good, or you are on a diet and want to lose weight). This happens in the hypothalamic or forebrain regions.
Applications to real life
People who are anorexic feel hunger, but they don't act on it because they think hunger is good because it causes them to lose weight, and satiation might be a punishment. On the contrast, people with binge-eating disorder, get signaled that they are full, but there is something else that propels them to eat.