Motivation

Question 1

What is motivation?

Answer 1

→ A physical need

→ Wanting/liking something

Question 2

What does the hypothalamus do?

Answer 2

→ Maintain homeostasis by regulating three interrelated functions

Question 3

What are the 3 things that the hypothalamus controls?

Answer 3

→ Endocrine secretion
→ Autonomic nervous system

→ Emotions and drive

Question 4

Describe anabolism

Answer 4

→ glucose goes to the liver

→ Skeletal muscle stores glucose as glycogen

Question 5

Describe catabolism

Answer 5

→ Glycogen gets broken down to glucose

Question 6

What is parabiosis?

Answer 6

→ Sharing of blood circulation between animals

Question 7

What do obese mice not produce?

Answer 7

→ leptin

Question 8

What happens if you connect an ob/ob mouse and a normal mouse via parabiosis?

Answer 8

→ the ob/ob mouse will decrease in size

Question 9

Where does leptin bind?

Answer 9

→ Leptin receptors on the arcuate nucleus

Question 10

When is leptin released and why?

Answer 10

→ When you finished eating

→ to stop feeding

Question 11

Where is the hypothalamus?

Answer 11

→ At the base of the brain

Question 12

What happens when you lesion the VMH?

Answer 12

→ weight gain

Question 13

What happens during lateral hypothalamic syndrome?

Answer 13

→ Diminished appetite for food

→ Anorexia

Question 14

What happens during ventromedial hypothalamic syndrome?

Answer 14

→ Overeating

→ Obesity

Question 15

What are the anorectic peptides?

Answer 15

→ Alpha MSH

→ CART

Question 16

Describe the anorexic response

Answer 16

→ Leptin increases in circulation
→ Leptin binds to receptors on the arcuate nucleus

→ Alpha MSH and CART neurons in arcuate nucleus are activated which project to the lateral hypothalamus
→ These neurons release alpha MSH and CART peptides
→ Peptides inhibit feeding

Question 17

Describe how the basal metabolic rate is increased during the anorexic response

Answer 17

→ Leptin stimulates the Alpha MSH and CART neurons of the Arcuate Nucleus.
→ These neurons extend from the Arcuate Nucleus to the Paraventricular Nucleus.

→ The Paraventricular Nucleus is stimulated and stimulates the release of ACTH and TSH from the Anterior Pituitary.
→ ACTH and TSH increases the basal metabolic rate.

Question 18

Describe the orexigenic response

Answer 18

→ Leptin levels are low.
→ CART and alpha MSH neurons of the Arcuate Nucleus are inhibited.

→ NPY and AgRP neurons in Arcuate Nucleus are activated which project to the lateral hypothalamus.
→ These neurons release NPY and AgRP peptides.
→ Peptides stimulate feeding.

Question 19

Describe how the basal metabolic rate is decreased during the orexigenic response

Answer 19

→ Low Leptin levels inhibits the Alpha MSH and CART neurons of the Arcuate Nucleus whilst activating the AgRP and NPY neurons.
→ These neurons extend from the Arcuate Nucleus to the Paraventricular Nucleus.

→ AgRP and NPY inhibit the Paraventricular Nucleus thus it cannot stimulate the release of ACTH and TSH from the Anterior Pituitary.
→ A lack of ACTH and TSH means a decreased basal metabolic rate.

Question 20

What do alpha MSH and AgRP bind to?

Answer 20

→ MC4 receptor

Question 21

What does alpha MSH do to the MC4 receptor?

Answer 21

→ It activates the receptor

→inhibits feeding

Question 22

What does AgRP do to the MC4 receptor?

Answer 22

→ Inhibits the receptor

→ Increases feeding

Question 23

What are the 2 lateral hypothalamic peptides?

Answer 23

→ Melanin concentrating hormone (MCH)

→ Orexin

Question 24

What are the 3 functions of orexins?

Answer 24

→ Promotes meal initiation
→ Decreases sleep and increases arousal

→ Promotes drug addition

Question 25

What is the function of MCH?

Answer 25

→ Prolongs consumption

Question 26

What does disruption of the hypothalamus cause?

Answer 26

→ Hyperphagia → Anorexia → bulimia

Question 27

What happens during the cephalic phase?

Answer 27

→ Secretion of saliva → Gastric juices secreted in the stomach in preparation for food → Activated NPY/AgRP

Question 28

What happens during the gastric phase?

Answer 28

More secretion of saliva → More secretion of gastric juice → Distension signals via the vagus nerve

Question 29

What two other substances are released during the gastric phase?

Answer 29

→ CCK | → Insulin

Question 30

What is the connection between serotonin and food?

Answer 30

→ 5-HT rises in anticipation of food | → Spikes during a meal

Question 31

What are the natural rewards?

Answer 31

→ Sex → Food → Water → nurturing

Question 32

What is the reward pathway in the brain?

Answer 32

→ Dopaminergic neurons that project from the VTA to the nucleus accumbens

Question 33

What do nicotine, cocaine and heroin cause?

Answer 33

→ Activation of the mesolimbic pathway

Question 34

How does cocaine work?

Answer 34

→ Blocks dopamine transporters in the nucleus accumbens

Question 35

How does heroin work?

Answer 35

→ Activates new opioid receptors in the VTA

Question 36

How does nicotine work?

Answer 36

→ Activates nicotinic receptors in the VTA

Question 37

What is positive reinforcement?

Answer 37

→ Anything added that follows a behaviour and makes it more likely that the behaviour will occur again in the future

Question 38

What is negative reinforcement?

Answer 38

→ A response or a behaviour that is strengthened by stopping, removing or avoiding a negative outcome

Question 39

What classifies someone as being an addict?

Answer 39

→ They suffer from physical and emotional withdrawal symptoms when the drug is taken away

Question 40

What do people who suffer from addiction have?

Answer 40

→ Suppressed reward systems

Question 41

What is wanting something driven by?

Answer 41

→ Dopamine

Question 42

What is liking something driven by?

Answer 42

→ Opioid system

Question 43

What is the prefrontal cortex involved in?

Answer 43

→ Willpower

Question 44

Why don't leptin injections work in humans?

Answer 44

→ Addiction is driven by many factors

Question 45

How are gut hormones involved in feeding behaviour?

Answer 45

→ acting via vagal afferents act on nuclei within the brainstem (NTS) which in turn signal to the hypothalamus. → Some gut hormones may also act directly on the hypothalamic nuclei via the circulation and across the blood-brain barrier

Question 46

How is the pre-frontal cortex involved in feeding behaviour?

Answer 46

conditioned taste aversion

Question 47

How is serotonin linked with food?

Answer 47

→ 5HT in hypothalamus → Rises in anticipation of food → Spike during a meal (carbohydrates in particular)

Question 48

What is low serotonin levels associate with?

Answer 48

→ anorexia nervosa, → bulimia with depression

Question 49

What is dopamine release in the nucleus accumbens correlated with?

Answer 49

→ correlated with motivation but not liking (hedonic)

Question 50

What is microdialysis?

Answer 50

→ Measuring neurotransmitter release in vivo | → Association with behaviour parameters

Question 51

How is the hippocampus involved in feeding behaviour?

Answer 51

→ involved in memory and learning. Memory of reward is strong in people developing dependence on food and drugs

Question 52

How is the amygdala involved in feeding behaviour?

Answer 52

emotionality. Extended amygdala in dependence

Question 53

What is observed in D2 receptor labelling of obese people?

Answer 53

→ downregulation of D2 receptors. | → So they increase feeding in order to get back to control normal states of satisfaction

Question 54

What are the short term regulation of feeding?

Answer 54

→ Gastric distension signals brain via vagus nerve. → CCK released in intestines in response to fats → Insulin also released by β cells of the pancreas— induces satiety by acting on arcuate nucleus of the hypothalamus

Question 55

What are the short term regulations of feeding in the cephalic phase?

Answer 55

→ Ghrelin released when stomach is empty | → Activates NPY/AgRP-containing neurons in arcuate nucleus

Question 56

What does removal of ghrelin-secreting cells in the stomach lead to?

Answer 56

loss of appetite

Question 57

What is the hypothalamus adjacent to?

Answer 57

Adjacent to third ventricle of the brain