21 Feeding and Eating Flashcards Preview

2911 Brain and Behaviour > 21 Feeding and Eating > Flashcards

Flashcards in 21 Feeding and Eating Deck (32):
1

What are the two metabolic states?

Catabolic - releasing and using energy, associated with weight loss
Anabolic - acquiring and storing energy, associated with weight gain

2

What can lipectomies in Siberian hamsters teach us about body weight?

Hamsters put weight back on almost immediately after lipectomy - which has only temporary effect on seasonal weight cycle. This suggests there is a set point of ideal weight, which regulates catabolic and anabolic systems.

3

What are the FIVE main hunger and satiety signals from the body?

1. Stomach stretch
2. Blood sugar
3. Leptin
4. Ghrelin
5. Insulin

4

How does stomach stretch send satiety signals to brain?

Stomach stretch is picked up by the somatosensory nerve and sent to nucleus of the solitary tract (NTS) in the medulla.

5

How does blood sugar send signals to brain?

Blood sugar is picked up by sugar-sensitive cells in the NTS

6

How do Leptin signals reach the brain?

Leptin is picked up by arcuate nucleus (ARC) of the hypothalamus. More leptin is produced when there is more body fat, sign to stop eating.

7

When is Ghrelin produced and what does it do?

Ghrelin – produced when stomach is empty – picked up by ARC. Spike in Ghrelin precedes eating.

8

What does Insulin tell the brain?

Insulin is picked up by ARC and indicates there is enough blood sugar.

9

What does the lateral hypothalamus (LH) do?

The lateral hypothalamus stimulates energy conservation "orexic" - seeking and storing food

10

How does the ARC operate in regards to the LVN and LH?

It switches them on or off.

11

If ghrelin picked up by ARC, what happens?

LH is stimulated and PVN is inhibited -> orexic state

12

If leptin or insulin picked up by ARC, what happens?

Leptin and insulin cause the ARC to inhibit the LH and stimulate the PVN

13

What does the paraventricular nucleus (PVN) of the hypothalamus do?


The paraventricular nucleus stimulates energy consumption "anorexic" - projects to pituitary gland, involved in fight-or-fight response

14

How does the PVN affect the autonomic nervous system?

The PVN sends signals to the medulla, stimulating the parasympathetic nervous system

15

What is the difference between wanting and needing food?

Our appetite for food is only vaguely related to our need for energy.

HOWEVER,
- We can crave food when we're sated.
- Starved people are not necessarily hungry
- Terminating meals has little to do with how many calories we've eaten

16

What is the role of the mesolimbic dopamine system in appetite?

The mesolimbic DA system is activated by food cues. Food causes spike in DA release in nucleus accumbens.

In conditioning experiments, DA released in nucleus accumbens upon presentations of CS associated with food, rather than food itself. DA in nucleus accumbens is linked to salience of reward, not to sensory pleasure of it.

In the obese, this happens even when sated. Obese are also more sensitive to external sensory cues – more DA released.

17

What role does the orbitofrontal cortex have in appetite?

It regulates the pleasure of eating food once satiety is reached. Craving a food increases pleasure; satiety decreases pleasure in eating. OFC contains pleasantness/satiety switch. In obese people this switch isn’t working so well – continue eating and finding food pleasant.

18

How does DA spike in nucleus accumbens affect LH?

NAc connects to LH which connects to VTA which connects to NAc which connects to cortex to drive behaviour. So when you get DA spike from seeing food, LH is stimulated (orexic state) and cortex is spurred to act.

19

What distinction does Schachter (1971) make between types of food-relevant cues?

Internal cues of hunger and satiety

External food or meal relevant cues - these can increase appetite, regardless of internal cues (cookie smell in waiting room example)

20

How, according to Schachter, does the reaction of obese people to these cues differ from that of the non-obese?

Obese are less sensitive to internal cues, more sensitive to external cues

21

What additional distinction did Herman and Polivy (2008) add?

External cues should be divided into -

Normative cues - eg. how much on plate, when others stop eating

Sensory cues - smells, taste, look of food

Obese people specifically sensitive to sensory cues

22

How does the behaviour of obese people in all-you-can-eat buffets differ from that of lean people?

Obese people pile up heaps of food, sit facing buffet. Sensitivity to sensory cues makes food taste better if exposed to more of it. And more likely to refill plate.

23

What's the difference between wanting a food and liking it?

Wanting it means now; liking means in general.

24

What additional distinction did Herman and Polivy (2008) add?

External cues should be divided into -

Normative cues - eg. how much on plate, when others stop eating

Sensory cues - smells, taste, look of food

Obese people specifically sensitive to sensory cues

25

How does the behaviour of obese people in all-you-can-eat buffets differ?

Obese people pile up heaps of food, sit facing buffet. Sensitivity to sensory cues makes food taste better if exposed to more of it. And more likely to refill plate.

26

What's the difference between wanting a food and liking it?

Wanting it means now; liking means in general.

27

How do rats' hedonic reactions to salt change over level of depletion?

The more depleted in salt the rats are, the more they show hedonic response, and less aversive response (gaping).

28

What evidence is there that the satiety/pleasantness switch isn't working in obese people?

They continue eating after satiety and continue finding food pleasant.

29

What effect does food palatability have on food consumption?

Highly palatable foods decrease effect of satiety on consumption - they disguise effect of satiety. (Palatable foods also tend to be energy dense.)

30

What role does the orbitofrontal cortex have in appetite?

It regulates the pleasure of eating food once satiety is reached. Craving a food increases pleasure; satiety decreases pleasure in eating. OFC contains pleasantness/satiety switch.

31

What evidence is there that the satiety/pleasantness switch isn't working in obese people?

They continue eating after satiety and continue finding food pleasant.

32

What effect does food palatability have on food consumption?

Highly palatable foods decrease effect of satiety on consumption - they disguise effect of satiety. Palatable foods also tend to be energy dense.