motivation

Question 1

Motivated behaviour

Answer 1

Driver/energizing of behaviour in pursuit of a goal, is a fundamental element of our interaction with the world and with each other.

Question 2

Orexinogenic peptides

Answer 2

Endogenous occurring neuropeptide hormone such as ghrelin, orexin, Agouti related peptide, Melanin-Concentrating Hormone or neuropeptide Y which increases appetite

Question 3

Anorectic peptides

Answer 3

Endogenous occurring neuropeptide such as aMSH or CART that suppress appetite

Question 4

What is motivation?

Answer 4

• Driving force
• Physical need
• Wanting, liking

Question 5

Hypothalamus

Answer 5

• Maintain homeostasis by regulating three interrelated functions
– endocrine secretion
– autonomic nervous system
– emotions and drive/behaviour
• Motivated behaviour, e.g. drinking, eating

Question 6

Long term regulation of bodyweight

Answer 6

Bodyweight is normally stable. If an animal is force-fed, it will gain weight. the weight is lost, however as soon as the animal can regulate its own food intake. Similarly, weight lose during a period of starvation is rapidly gained when food is freely available

Question 7

Feedback of leptin

Answer 7

fatty tissues produce leptin when satisfied

then leptin travels to the brain to tell you to stop eating

Question 8

Lateral hypothalamic syndrome

Answer 8

diminished appetite for food; anorexia

Question 9

Venteromedial hypothalamic syndrome

Answer 9

overeating and obesity

Question 10

Response to elevated leptin levels

Answer 10

• Activation of arcuate neurons that release αMSH and CART peptides
– Anorectic peptides—diminish appetite
– Project to regions that orchestrate coordinated response of humoral, visceromotor, and somatic responses

Question 11

Paraventricular nucleus

Answer 11

(humoral response)

Question 12

Intermediolateral gray matter of spinal cord

Answer 12

(visceromotor response)

Question 13

Lateral hypothalamus

Answer 13

(somatic response)

Question 14

LH neurons stimulating feeding behaviour contain

Answer 14

–	Melanin-concentrating hormone (MCH) 
•	Widespread connections in the brain
•	Prolongs consumption
–	Orexin
•	Also with widespread cortical connections
•	Promotes meal initiation

Question 15

Hypothalamus and the control of bodyweight and food intake

Answer 15

• Motivated behaviour
• Accurately regulated by leptin produced by adipose tissue and hypothalamic peptides
• Hypothalamus plays an important role in regulating feeding behaviour (long term)
• Disruption of this regulation leads to
– Hyperphagia
– Anorexia
– Bulimia nervosa

Question 16

Short term regulation of feeding

Answer 16

• Motivation to eat also depends on:

• How long it has been since last meal
• How much one has already eaten
• What type of food has already been eaten

Question 17

Satiety

Answer 17

• Satiety is the feeling of fullness and the suppression of hunger for a period of time after a meal
• Feelings of satiety can influence how soon and how much you next eat
• The feeling of satiety occurs due to a number of bodily signals that begin when a food or drink is consumed and continue as it enters the gut and is digested and absorbed

Question 18

Short term regulation of feeding (cephalic phase)

Answer 18

• Cephalic: hunger
– Ghrelin released when stomach is empty
– Activates NPY/AgRP-containing neurons in arcuate nucleus
– Removal of ghrelin-secreting cells of stomach thought to cause loss of appetite

Question 19

Short term regulation of feeding (satiety signals which ends meal)

Answer 19

– Gastric distension signals brain via vagus nerve.
– Works synergistically with CCK released in intestines in response to certain foods
– Insulin also released by β cells of the pancreas— induces satiety by acting on arcuate nucleus of the hypothalamus

Question 20

Why do we eat?

Answer 20

• We like food
– Hedonic aspect
• We want food
– Drive reduction
– Liking and wanting mediated in part by separate brain circuits
• Dopaminergic system involved in wanting/ craving (or liking?)

Question 21

Reinforcement and reward

Answer 21

• Positive reinforcement (anything added that follows a behavior that makes it more likely that the behavior will occur again in the future)
• Negative reinforcement (a response or behavior is strengthened by stopping, removing or avoiding a negative outcome or aversive stimulus)

Question 22

Natural rewards

Answer 22

Food, water, sex, nurturing

Question 23

Addiction

Answer 23

Acute reinforcement/social drug taking
Escalating/compulsive use
Dependence 
Withdrawal 
Protected withdrawal

potential recovery but then there could be a relapse

Question 24

Dopamine and reinforcement

Answer 24

• Dopamine release in the nucleus accumbens is correlated with motivation but not liking (hedonic)
• Its also release in anticipation of reward
• Note that dopamine also involved in movement

Question 25

Microdialysis

Answer 25

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

Question 26

Serotonin, Food and mood

Answer 26

• Mood and food are connected – 5HT in hypothalamus • Rises in anticipation of food • Spike during a meal (carbohydrates in particular) • Association anorexia nervosa, bulimia with depression (low serotonin)